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KjelMaster K-375 with KjelSampler K-376 / K-377
Operation Manual
11593514E en
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Imprint
Product Identification:
Operation Manual (Original), KjelMaster K-375 with KjelSampler K-376 / K-377
11593514 en
Publication date: 12.2018
BÜCHI Labortechnik AG
Meierseggstrasse 40
Postfach
CH-9230 Flawil 1
E-Mail: quality@buchi.com
BUCHI reserves the right to make changes to the manual as deemed necessary in the light of experience; especially in respect to structure, illustrations and technical detail.
This manual is copyright. Information from it may not be reproduced, distributed, or used for competitive purposes, nor made available to third parties. The manufacture of any component with the aid of this manual without
prior written agreement is also prohibited.
Page 3
Document History
Index Date Author Changes
A 25/MAY/2012 NAGG Initial version
B 16/JUL/2013 NAGG First revised version
C 17/NOV/2014 HILS/BRUS Second revised version
(update colorimetric titration)
D 28/APR/2016 HILS Removal of Declaration of Conformity
E 12/DEC/2018 HOES Third revised version
(update colorimetric titration)
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Read this manual carefully before installing and running your system and note the safety precautions in chapter 2 in
particular. Store the manual in the immediate vicinity of the instrument, so that it can be consulted at any time.
No technical modifications may be made to the device without the prior written agreement of BUCHI. Unauthorized
modifications may affect the system safety or result in accidents.
This manual is copyright. Information from it may not be reproduced, distributed, or used for competitive purposes,
nor made available to third parties. The manufacture of any component with the aid of this manual without prior
written agreement is also prohibited.
If you need another language version of this manual, you can download it at
www.buchi.com.
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Table of contents
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K-375 / K-376 / K-377 Operation Manual, Version E
Table of contents
1 About this manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9
1.1 Trademarks 9
1.2 Abbreviations 9
2 Safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
2.1 User qualification 10
2.2 Proper use 10
2.3 Improper use 10
2.4 Safety warnings and safety signs used in this manual 11
2.5 Product safety 12
2.5.1 General hazards 12
2.5.2 Instrument-related hazards 13
2.5.3 Other hazards 14
2.5.4 Personal protective equipment 14
2.5.5 Built-in safety elements and measures 15
2.6 General safety rules 16
3 Technical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
3.1 Scope of delivery 17
3.1.1 Basic devices 17
3.1.2 Standard accessories for K-375 19
3.1.3 Standard accessories for K-376 / K-377 21
3.1.4 Operation Manuals for K-375 22
3.1.5 Optional accessories K-375 23
3.1.6 Optional accessories K-376 / K-377 25
3.2 Technical data overview 26
3.2.1 Technical data KjelMaster K-375 and KjelSampler K-376 / K-377 26
3.2.2 Technical data titrator 27
3.3 Determination parameters 28
3.4 Information on type plate 29
3.4.1 Titrator module and dosing unit 29
3.4.2 Material on the K-375 29
3.4.3 Material on the K-376 / K-377 30
4 Description of function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
4.1 Device overview 31
4.1.1 Opening the service door 32
4.2 Functional principle of KjelMaster System K-375 / K-376 / K-377 33
4.3 Standby function 35
4.4 System preparation 35
4.4.1 Preheating 35
4.4.2 Priming 35
4.4.3 Cleaning 35
4.4.4 Aspiration 35
4.5 Distillation and titration 36
4.5.1 Distillation and Titration Options 36
4.5.2 Distillation Mode 36
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4.5.3 Titration Type 36
4.5.4 Sensor Type 36
4.5.5 Titration Mode 37
4.5.6 Measuring Mode 37
4.5.7 Titration Algorithm 37
4.5.8 Determination Mode 37
4.6 Different methods 38
4.7 Blank values 38
4.7.1 Blanks 38
4.7.2 Control blanks 39
4.8 Reference substances 39
4.9 Indicator for colorimetric titration 40
4.10 Result Groups 40
4.11 Explanation of alkaline direct distillation 41
5 Putting into operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
5.1 Installation site 43
5.2 Electrical connections 44
5.2.1 Connections of the KjelMaster K-375 44
5.2.2 Connections of the K-376 / K-377 45
5.3 Transfer connection K-376 / K-377 to K-375 46
5.3.1 Connecting the K-376 to the K-375 46
5.3.2 Connecting the transfer hoses of the K-377 48
5.4 Reagent/water and waste connections 49
5.5 Buret unit for titrant 51
5.6 Positioning of the dosing tip 53
5.7 Storage tank connection 53
5.8 Level sensors 54
5.9 Installation of the titration sensor 56
5.9.1 Potentiometric sensor 56
5.9.2 Colorimetric sensor 56
5.10 Connections to peripheral devices 57
5.10.1 Connecting a printer 57
5.10.2 Connecting a network cable 57
5.10.3 Connecting a KjelSampler K-376 or K-377 57
5.10.4 Connecting a balance 57
5.10.5 Connecting a bar code reader 58
5.10.6 External dosing unit for back titration 58
5.11 Preparing the system 58
5.11.1 Preparing the software 58
5.11.2 Preparing the hardware 59
6 Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .60
6.1 The operating principle 60
6.2 The home screen 60
6.2.1 The title bar 62
6.2.2 The bottom bar 62
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6.2.3 System status icons 63
6.3 User concept 63
6.4 Editable and non-editable menu items 63
6.5 The status view 65
6.5.1 RESULT display 66
6.5.2 CHART display 67
6.6 Determination 67
6.6.1 System Preparation 69
Single Sample 77
6.6.3 Sample Lists 79
6.6.4 Sequences 84
6.7 Results 92
6.7.1 Result groups 92
6.7.2 Last Results 94
6.7.3 Blank Correction 95
6.8 Determination Parameters 99
6.8.1 Methods 99
6.8.2 Volumetric Solutions 108
6.8.3 Reference Substances 109
6.9 Device 110
6.9.1 Settings 110
6.9.2 Utilities 117
6.9.3 Diagnostics 118
6.9.4 Logout 119
7 Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
7.1 Daily maintenance 120
7.1.1 Before sample determination (potentiometry) 120
7.1.2 Before sample determination (colorimetry) 121
7.1.3 After sample determination 122
7.1.4 pH electrode 122
7.1.5 Filling boric acid into receiving vessel after last sample of rack was determined
(potentiometry only) 123
7.1.6 Sample tube cleaning 124
7.2 Weekly maintenance 125
7.2.1 Cleaning the housing 125
7.2.2 Cleaning the titrator 125
7.2.3 Cleaning the glass parts of the dosing unit 125
7.2.4 Cleaning the dip tube of the KjelSampler 125
7.2.5 Device monitoring 126
7.2.6 Cleaning colorimetric sensor and mesh 127
7.3 Monthly maintenance 127
7.3.1 Calibrating the pump 127
7.3.2 Checking the distillate amount 129
7.3.3 Inspecting the buret 130
7.3.4 Inspecting the titrator 130
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7.3.5 Inspecting the sample tubes 130
7.4 Half-yearly maintenance 132
7.4.1 K-375 Sealing between sample tube and splash protector 132
7.4.2 K-376 / K-377 dip tube and sealing cap 133
7.4.3 Replacing the splash protector 134
7.5 Yearly maintenance 136
7.5.1 Replacement of wear parts 136
7.5.2 Decalcification of the steam generator 137
7.5.3 Replacement of the sodium hydroxide pump 137
7.5.3 Replacement of the wave spring 138
7.6 Replace every two years 139
7.6.1 Replacement of the transfer connection 139
7.7 Maintenance work if required 141
7.7.1 Changing the buret tip 141
7.7.2 Cleaning the pH electrode 141
7.7.3 Replacing the buret 142
7.7.4 Cleaning the splash protector and the rubber seal 142
7.7.5 Glass parts 142
7.7.6 Troubleshooting the dosing unit 143
7.7.7 Adjusting the sample tube holder 143
7.8 Customer service 144
8 Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145
8.1 Problems that may occur 145
8.2 Error messages on the display of the K-375 149
8.3 Eliminating errors of the KjelSampler K-376 / K-377 153
8.4 Eliminating errors of the titrator 154
9 Taking out of operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155
9.1 Emptying the steam generator 155
9.2 Emptying the buret of the titrator 156
9.3 Storage/shipping 156
9.4 Disposal 156
10 Spare parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157
10.1 Spare parts K-375 157
10.2 Spare parts K-376 / K-377 160
10.3 Hosing connection scheme Kjeldahl Sampler System K-375 / K-376 160
11 Declarations and requirements 161
11.1 FCC requirements (for USA and Canada) 161
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1 About this manual
9
K-375 / K-376 / K-377 Operation Manual, Version E
1 About this manual
This manual describes the KjelMaster System K-375 / K-376 / K-377 and provides all information
required for its safe operation and to maintain it in good working order.
It is addressed to laboratory personnel in particular.
NOTE
The symbols pertaining to safety (DANGER, CAUTION and WARNING) are explained in chapter 2.
1.1 Trademarks
DURAN® is a registered trademark of the SCHOTT AG.
Nylflex® is a registered trademark of the Pedex & Co. GmbH.
1.2 Abbreviations
CSM: Chopped Strand Mat
ETFE: Polytetrafluorethylene
FEP: Fluorinated Ethylene Propylene
KCI: Potassium chloride
PCTFE: Polychlorotrifluoroethylene
PMMA: Polymethyl methacrylate
POM: Polyoxymethylene
PP: Polypropylene
PTFE: Ethylenetetrafluoroethylene
PUR: Polyurethane
UV: Ultraviolet
EPDM: Ethylene propylene diene monomer
PVDF: polyvinylidene difluoride
PA: Polyamides
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1 About this manual
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K-375 / K-376 / K-377 Operation Manual, Version E
2 Safety
This chapter points out the safety concept of the device and contains general rules of behavior and
warnings from hazards concerning the use of the product.
The safety of users and personnel can only be ensured if these safety instructions and the safety
related warnings in the individual chapters are strictly observed and followed. Therefore, the manual
must always be available to all persons performing the tasks described herein.
2.1 User qualification
The device may only be used by laboratory personnel and other persons who on account of training
or professional experience have an overview of the dangers which can develop when
operating the instrument.
Personnel without this training or persons who are currently being trained require careful instruction.
The present Operation Manual serves as the basis for this.
2.2 Proper use
The device has been designed and built for laboratories. It serves for nitrogen determination
according to Kjeldahl. The KjelMaster K-375 as stand-alone device may also be used for distillations
of steam-volatile substances.
2.3 Improper use
Applications not mentioned above are improper. Also applications which do not comply with the technical data are considered improper.
!
Danger
During any improper use, the effectiveness of the protection systems of the devices
can be affected.
∙ Avoid any improper use of the devices!
The operator bears the sole risk for any damages caused by such improper use.
The following uses are expressly forbidden:
∙ Use of the device in rooms which require ex-protected devices.
∙ Use on samples which can explode or inflame (e.g.: explosives, etc.) due to shock, friction, heat
or spark formation.
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2.4 Safety warnings and safety signs used in this manual
DANGER, WARNING, CAUTION and NOTICE are standardized signal words for identifying levels of
hazard seriousness of risks related to personal injury and property damage. All signal words, which
are related to personal injury are accompanied by the general safety sign.
For your safety it is important to read and fully understand the table below with the different signal
words and their definitions!
Sign Signal word Definition Risk level
DANGER
Indicates a hazardous situation which, if not
avoided, will result in death or serious injury.
★★★★
WARNING
Indicates a hazardous situation which, if not
avoided, may result in serious injury or death.
★★★☆
CAUTION
Indicates a hazardous situation which, if not
avoided, may result in minor or moderate injury.
★★☆☆
NOTICE
Indicates possible material damage, but no practices related to personal injury.
☆☆☆☆
Supplementary safety information symbols may be placed in a rectangular panel on the left to the
signal word and the supplementary text (see example below).
Space for
supplementary safety
information
symbols.
SIGNAL WORD
Supplementary text, describing the kind and level of hazard / risk seriousness.
∙ List of measures to avoid the herein described, hazard or hazardous situation.
∙ ...
∙ ...
Table of supplementary safety information symbols
The reference list below incorporates all safety information symbols used in this manual and their
meaning.
Warning safety symbols
Symbol Meaning Symbol Meaning
General warning Corrosive hazard
Electrical hazard Flammable
Biohazard Explosive environment
Broken glass Inhalation harmful
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Symbol Meaning Symbol Meaning
Device damage Hot surface
Hand bruising Magnet
Mandatory safety symbols
Symbol Meaning Symbol Meaning
Wear protective goggles Wear protective clothes
Wear protective gloves Heavy load, lift with assistance
Additional user information
Paragraphs starting with NOTE transport helpful information for working with the device / software or
its supplementaries. NOTEs are not related to any kind of hazard or damage (see following example).
NOTE
Useful tips for the easy operation of the instrument / software.
2.5 Product safety
The device is designed and built in accordance with current state-of-the-art technology. Nevertheless, risks to users, property, and the environment can arise when the device is used carelessly or
improperly.
The manufacturer has determined residual dangers emanating from the instrument
if the device is operated by insufficiently trained personnel.
if the device is not operated according to its proper use.
Appropriate warnings in this manual serve to make the user alert to these residual dangers.
2.5.1 General hazards
The following safety messages show hazards of general kind which may occur when handling the
instrument. The user shall observe all listed counter measures in order to achieve and maintain the
lowest possible level of hazard.
Additional warning messages can be found whenever actions and situations described in this manual
are related to situational hazards.
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Danger
Death or serious injuries by use in explosive environments.
∙ Do not store or operate the device in explosive environments.
∙ Remove all sources of flammable vapors.
∙ Do not store chemicals in the vicinity of the device.
Caution
Risk of minor or moderate cuts by sharp edges.
∙ Do not touch defective or broken glassware with bare hands.
∙ Do not touch thin metal edges.
Notice
Risk of device damage by liquids or mechanical shocks.
∙ Do not spill liquids over the device or its components.
∙ Do not drop the device or its components.
∙ Keep external vibrations away from the instrument.
2.5.2 Instrument-related hazards
!
CAUTION
Risk of injury.
∙ Never touch the surface of the touch screen with pointed or sharp objects!
Otherwise the screen might get damaged and splinter.
!
CAUTION
Risk of burns by hot surface. Surface temperature exceeds 60 °C.
∙ Do not touch hot surfaces of the instrument.
!
CAUTION
Risk of pinch point injuries.
∙ In order to avoid injuries to the hands and fingers the K-376 and K-377 Kjel-
Samplers may not be manipulated during the moving action of the sampler
arm.
!
CAUTION
Risk of burns by hot steam.
∙ The system works with hot steam. Avoid any contact with hot steam.
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!
DANGER
Risk of chemical burns by corrosives.
∙ Wear laboratory coat, protective gloves and protective goggles at all times.
!
DANGER
Risk of chemical burns by corrosives.
∙ During operation the sample tube contains either strong acid or strong base. In
case the sample tube brakes, the content of the sample tube is collected in the
drip tray on the bottom of the housing. Wear laboratory coat protective gloves
and protective goggles when emptying the drip tray.
2.5.3 Other hazards
Fundamental dangers arise from.
∙ acids and lye
∙ flammable gases or solvent fumes in the direct vicinity of the instrument
∙ damaged glass parts
∙ insufficient distance between the device and the wall (see chapter 5.1, Installation site)
∙ burns caused by contact with hot glass parts
∙ burns caused by contact with steam at the waste-outlet
∙ defective transfer tube: escape of steam and/or sulfuric acid
2.5.4 Personal protective equipment
Always wear personal protective equipment such as protective eye goggles, protective clothing and
gloves. The personal protective equipment must meet all requirements of all data sheets for the
chemicals used. These instructions are an important part of the K-375, K-376 and K-377 and must be
made available at all times to the operating personnel at the place where the equipment is deployed.
This also applies to additional language versions of these instructions, which can be reordered separately.
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!
WARNING
Serious chemical burns by corrosives.
∙ Observe all data sheets of the used chemicals.
∙ Handle corrosives in well ventilated environments only.
∙ Always wear protective goggles.
∙ Always wear protective gloves.
∙ Always wear protective clothes.
∙ Do not use damaged glassware.
2.5.5 Built-in safety elements and measures
The KjelMaster K-375 has monitored protective doors which prevent a distillation to start while a door is
open. A running distillation is immediately interrupted when a door is opened. The dosing of reagents is
also immediately stopped.
The sample changers K-376 / K-377 have monitored protective shields. Running a sample changer with
opened shield is impossible. For the K-377 only the shield of the tray, that is currently not in use can be
opened.
K-375:
∙ Protective door: Safety appliance to protect users from burns at the splash protector (distillation
area) which is hot during distillation.
∙ Protective door sensors: Prevents to start a distillation with the protective doors open and stops the
distillation as soon as a protective door is opened during the process.
∙ Sample tube sensor: Prevents to start a distillation without a sample tube inserted.
∙ Service door sensor/switch: Electrical power is disconnected immediately when the service door is
opened, thus preventing electrical shock during maintenance.
K-376:
∙ Protective shield with sensor/switch: As soon as the shield is opened an alarm sound is triggered
and any movement of the arm is stopped.
K-377:
∙ Protective shield with sensor/switch: As soon as the shield of the tray in use is opened an alarms
sound is triggered and any movement of the arm is stopped. (The shield of the respective tray that
is not operated can still be opened without any restrictions.)
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2.6 General safety rules
Responsibility of the operator
The head of the laboratory is responsible for training his/her personnel.
The operator shall inform the manufacturer without delay of any safety-related incidents which might
occur during operation of the device or its accessories. Legal regulations, such as local, state and
federal laws applying to the device or its accessories must be strictly followed.
Duty of maintenance and care
The operator is responsible for the proper condition of instrument. This includes maintenance, service
and repair jobs that are performed on schedule by authorized personnel only.
Spare parts to be used
Use only genuine consumables and spare parts for maintenance to assure good system perfor-
mance, reliability and safety. Any modifications of spare parts or assemblies are only allowed with the
prior written permission of the manufacturer.
Modifications
Modifications to the device are only permitted after prior consultation and with the written approval
of the manufacturer. Modifications and upgrades shall only be carried out by an authorized BUCHI
technical engineer. The manufacturer will decline any claim resulting from unauthorized modifications.
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3 Technical data
This chapter introduces the reader to the device specifications. It contains the scope of delivery, technical data, requirements and performance data.
3.1 Scope of delivery
3.1.1 Basic devices
KjelMaster K-375 Order number
KjelMaster K-375
with glass splash protector and
potentiometric sensor
(220 – 240 V, 50/60 Hz)
113751700
KjelMaster K-375
with glass splash protector and
colorimetric sensor
(220 – 240 V, 50/60 Hz)
113752700
KjelMaster K-375
with plastic splash protector and
potentiometric sensor
(220 – 240 V, 50/60 Hz)
113753700
KjelMaster K-375
with plastic splash protector and
colorimetric sensor
(220 – 240 V, 50/60 Hz)
113754700
KjelSampler K-376 Order number
KjelSampler K-376
with one tray
(100 – 240 V, 50/60 Hz)
113750710
KjelSampler K-377 Order number
KjelSampler K-377
with two trays
(100 – 240 V, 50/60 Hz)
113750720
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KjelMaster System K-375 / K-376 Order number
KjelMaster System K-375 / K-376
K-375 with glass splash protector and
potentiometric sensor
K-375: 220 – 240 V, 50/60 Hz
K-376 / K-377: 100 – 240 V, 50/60 Hz
113751710
KjelMaster System K-375 / K-376
K-375 with glass splash protector and
colorimetric sensor
K-375: 220 – 240 V, 50/60 Hz
K-376 / K-377: 100 – 240 V, 50/60 Hz
113752710
KjelMaster System K-375 / K-376
K-375 with plastic splash protector and
potentiometric sensor
K-375: 220 – 240 V, 50/60 Hz
K-376 / K-377: 100 – 240 V, 50/60 Hz
113753710
KjelMaster System K-375 / K-376
K-375 with plastic splash protector and
colorimetric sensor
K-375: 220 – 240 V, 50/60 Hz
K-376 / K-377: 100 – 240 V, 50/60 Hz
113754710
KjelMaster System K-375 / K-377 Order number
KjelMaster System K-375 / K-377
K-375 with glass splash protector and
potentiometric sensor
K-375: 220 – 240 V, 50/60 Hz
K-376 / K-377: 100 – 240 V, 50/60 Hz
113751720
KjelMaster System K-375 / K-377
K-375 with glass splash protector and
colorimetric sensor
K-375: 220 – 240 V, 50/60 Hz
K-376 / K-377: 100 – 240 V, 50/60 Hz
113752720
KjelMaster System K-375 / K-377
K-375 with plastic splash protector and
potentiometric sensor
K-375: 220 – 240 V, 50/60 Hz
K-376 / K-377: 100 – 240 V, 50/60 Hz
113753720
KjelMaster System K-375 / K-377
K-375 with plastic splash protector and
colorimetric sensor
K-375: 220 – 240 V, 50/60 Hz
K-376 / K-377: 100 – 240 V, 50/60 Hz
113754720
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3.1.2 Standard accessories for K-375
Description Order number Picture
Sample tube (300 mL) —
1
Pair of glass tongs 002004
2
Connection cable RJ45 length 2 m 044989
Mains cable of the following types
Type CH
Type Schuko/Japan
Type GB
Type AUS
Type USA
010010
010016
017835
017836
033763
pH electrode
or (according to purchase order)
colorimetric sensor
Accessory kit for colorimetric sensor (if device version with colorimetric sensor is shipped)
11056842
11066601
11068260
3
4
Indicator according to Sher, 100 mL (if device version with colorimetric sensor is shipped)
003512
5
Buffer set pH 4 and pH 7, 3 x 20 mL each (if device version with
potentiometric sensor is shipped)
043188
KCI electrolyte, sat. , 250 mL (if device version with potentiometric
sensor is shipped)
11059759
6
Connection grommet for Chiller 049151
7
Hose connector in line 11–13 for waste tank 043178
Hose chemical supply, Nylflex, length 6 m, Ø 5/10 mm 043185
Suction tube to tanks, FEP, length 580 mm 043407
Hose waste drain, EPDM, L = 1.8 m, ø 11/18 mm 043457
Clamp D15.6 049167
Clamp D12.8 043297
Clamp D11.9 043841
Silicone hose ø 8 mm/12x1.8m 11058157
Y-piece ø12 mm 11058358
Cooling water hose complete: G 3/4”, G 1/2”, L = 1.5 m 037780
O-ring 190.1 x 3.53 EPDM 75 049676
8
O-ring 247.2 x 3.53 EPDM 11058241
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20
Description Order number Picture
FEP tube, 1.2 m, to driving motor 11056837
Capacitive level sensor for chemical or waste tank 11055914
9
Laboratory vessel 053203
Driving motor for dosing unit 11056835
10
Dosing unit (20 mL) 11056836
11
Test gauge sample tube holder 11059802
12
Tank 10 L 043410
13
Cap for 10 L tank, large 025869
14
Cap for 10 L and 20 L tank, small 043477
15
Tank labels 043434
Tank 20 L 043408
16
Cap for 20 L tank, large 043478
17
Distance holder for dosing tip 043203
18
Mini gender changer 043108
Weighing boats (20 pcs) 11060522
EPDM sealing for tanks 043048
Open end spanner 11058252
19
Tool SVL 22 11057779
20
CD KjelLink PC software (with 60 days test license) 11058664
1 2
3 4
5
7
9
16 17
10 11
12
13 14
15 18 20
8
19
6
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3.1.3 Standard accessories for K-376 / K-377
Description Order number Picture
K-376 / K-377 cable RS232 (crossed) 043920
1
Sample tube 500mL 026128
2
Clamp ring 043238
3
Hose clamp 022352
4
Fastener for transfer tube (K-376 only) 043482
Sample tubes (set of 4), 300mL 037377
5
Express rack, 4 places (K-376 only) 11057711
6
Rack, 20 places 11059831
7
Mains cable of the following types:
Type CH
Type Schuko/Japan
Type GB
Type AUS
Type USA
10010
10016
17835
17836
33763
Test gauge for sample tubes 11058240
8
1
6
3 42
7
8
5
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3.1.4 Operation Manuals for K-375
Description Order number
English 11593514
German 11593515
French 11593516
Italian 11593517
Spanish 11593518
Chinese 11593519
Japanese 11593520
Russian 11593653
KjelMaster K-375 Network Connection 11593539
KjelMaster K-375 - Data Export 11593558
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3.1.5 Optional accessories K-375
Description Order number Picture
Sample tubes (set of 4) 100 mL 11057442
1
Sample tubes (set of 4) 300mL 037377
2
Sample tubes (set of 20) 300 mL 11059690
2
Sample tubes (set of 4) graduated 300 mL 043049
Sample tubes (set of 4), 500mL 043982
4
Sample tube holder for 4 sample tubes 500mL each 016951
Receiving vessel 340mL 043333
5
Receiving vessel 420mL 043390
6
10 L chemicals 043468
7
10 L waste 043470
8
20 L chemicals 043469
9
20 L waste 043471
10
O-ring level sensor (10 L tank) 049676
11
O-ring level sensor (20 L tank) 11058241
12
Buffer solution pH 4, 250mL 11064974
Buffer solution pH 7, 250mL 11064975
Temperature sensor for titrator 11056851
13
2% boric acid with Sher indicator 11064972
4% boric acid with Sher indicator 11064973
4% boric acid with bromocresol green/methyl red indicator 11064976
Dosing unit (for back titration) 11056836
14
Driving motor for dosing unit 11056835
15
IQ/OQ set K-375 (English) 11058677
IQ/OQ set K-375 / K-376 / K-377 (English) 11058678
Repeating OQ set K-375 (English) 11058679
Repeating OQ set K-375 / K-376 / K-377 (English) 11058680
Glass splash protector 043332
16
Plastic splash protector 043590
17
Devarda splash protector 043335
18
Adapter set for 3rd party sample tubes 11058410
19
Receiving vessel, colorimetric titration 11068263
3
20
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2
7
15
17
16
18
13
14
8 109
3 4
5
11 12
1 6
19
20
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3.1.6 Optional accessories K-376 / K-377
Description Order number Picture
Stand for rack 11058659
1
Rack for 12 sample tubes, 500mL 043970
2
Retainer plate (holds tubes firmly in rack for machine
washing)
038559
3
Set of 10 boiling rods for digestion of samples with
tendency of boiling retardation (alternative for boiling chips)
043087
4
Dip tube with cross-slot for soil/stone containing samples 047845
5
Glassfinger for sample tubes
for soil samples
048638
6
1
4 5 6
2 3
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3.2 Technical data overview
3.2.1 Technical data KjelMaster K-375 and KjelSampler K-376 / K-377
KjelMaster K-375 KjelSampler K-376 KjelSampler K-377
Connection voltage 220 – 240 VAC
±10%
100 – 240 VAC
±10%
100 – 240 VAC ±10%
Frequency 50/60 Hz 50/60 Hz 50/60 Hz
Power consumption max. 2.2 kW max. 150 W max. 150 W
Current consumption
(230 V)
9.5 A 650 mA 650 mA
Weight 32 kg 40 kg
(without rack and
sample tubes)
64 kg
(without rack and
sample tubes)
Dimensions (W x H x D) 458 x 670 x 431 mm 505 x 750* x 655
* 1000 mm height
required to allow free
movement of the
sampler arm
1015 x 750** x 655
**1250 mm height
required to allow free
movement of the
sampler arm
Interfaces RS232 RS232 RS232
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Recovery rate
> 99.5% (1 – 200
mg N)
Reproducibility (RSD)
< 1%
Measuring range 0.02 – 200 mg N
Environmental conditions
Temperature
Altitude
Humidity
for indoor use only
+ 5 °C to + 40 °C
up to 2000 m above sea level
maximum relative humidity 80% for temperatures up to 31 °C, decreasing
linearly to 50% relative humidity at 40 °C
Mains connection Device plug C14 Device plug C14 Device plug C14
Overvoltage category II II II
Pollution degree 2 2 2
Approval CE/CSA CE/CSA CE/CSA
3.2.2 Technical data titrator
The following sensors can be connected to the titrator:
∙ combined pH glass electrode
∙ optical sensor
∙ temperature measuring sensor for Resistance Thermometer Pt 1000, connection: 2 x 4 mm
sockets and 1 x 2 mm socket
Dosing accuracy:
According to DIN EN ISO 8655, Part 3, or better
Typical accuracy: Fulfills ISO/DIN 8655-3 regulation
Measuring input: pH/mV input with 12 bit transducer for accurate resolution during the titration
Connection:
electrode socket according to DIN 19 262 or BNC socket and reference elec
trode 1 x 4 mm socket
Measuring range Display resolution Accuracy* without
sensor
Input resistance (Ω)
pH 0…14 0.01 0.05 ±1 digit > 5·10
12
mV –1400 ... +1400 0.1 2 ±1 digit > 5·10
12
sensor Measuring range Display resolution Accuracy* without
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T [°C] –30…115 0,1 0,5 K ±1 digit
*Accuracy:
Indicated in terms of measuring incertainty with a confidence of 95%. In addition the measuring
uncertainty of the sensor has to be taken into account as well. For pH electrodes e.g.: ∆
pH=0.012...0.03 according to DIN 19 266, Part 3.
3.3 Determination parameters
The amount of sample and the concentration of the titrant should be optimized, so that the titrant
volume is between 3 and 17mL (buret volume: 20mL).
Nitrogen
content
absolute
Nitrogen
content
relative
Protein content
relative (Protein
factor 6.25)
Sample
size
Boric acid
concentration
Titrant
concentration
Titrant
volume
0.02 mg 20 ppm 1.0 g 2 % (+3 g
KCl/L)
0.005 N 2 mL
0.1 mg 100 ppm 1.0 g 2 % 0.005 N 3 mL
1 mg 0.2 % 1 % 0.2 g 2 % 0.01 N 8 mL
5 mg 1 % 6 % 0.5 g 2 % 0.1 N 4 mL
10 mg 1 % 6 % 1.0 g 4 % 0.1 N 8 mL
20 mg 2% 13 % 1.0 g 4 % 0.1 N 14 mL
50 mg 5 % 31 % 0.4 g 4 % 0.1 N 14 mL
100 mg 10 % 63 % 1.0 g 4 % 0.5 N 14 mL
100 mg 20 % 0.5 g 4 % 0.5 N 14 mL
200 mg 20 % 1.0 g 4 % 0.5 N 28 mL
General recommendation
The correction factor for self prepared solutions is called titer.
The use of standardized titration solutions make a titer determination unnecessary.
Exact titrant concentration = concentration x titer
The titer of the titrant must be known. In case, it is unknown, it must be determined.
Example: Exact titrant concentration = 0.100 mol/L x 0.998
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3.4 Information on type plate
1
Device type code
2
Serial number
3
Supply voltage range/type
4
Frequency of supply voltage
5
Nominal power rating
6
Year of manufacture
Materials used
3.4.1 Titrator module and dosing unit
part Material designation
Housing sheet steel
Note
For the materials of the Dosing Unit, please refer to its manual which is delivered together with
dosing unit.
3.4.2 Material on the K-375
Part Material Material code
Housing Polyurethane PUR/UL VO
Glass parts Borosilicate glass 3.3 DIN/ISO 3585
Insulation steam generator Ceramic fiber Multitherm 550
Steam generator housing Stainless steel 1.4301
Protective door Polymethyl methacrylate PMMA
Seal ring
Chlorosulfonyl polyethylene elastomer
CSM
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3.4.3 Material on the K-376 / K-377
Part Material Material code
Housing (mounting plate) Steel sheet St 12 ZE 1.0330
Housing (casing-below) Stainless steel 1.4301 (L 314)
Housing (top cover) Alu-sheet AlMgSi1
Guide express rack PP PP
Coating Polyester/Epoxy PEP 31
Protective shield Polymethyl methacrylate/Alu PMMA/Alu
Drip tray Polypropylene PP
Housing y-axle Alu-sheet AlMgSi1
End cap y-axle POM POM
Dip tube PVDF PVDF
Sealing cap EPDM EPDM
Transfer hose linear PTFE PTFE
Steam tube Silicone/polyester MQ-PU
Protective hose PP PP
Hose chain PA PA
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4 Description of function
This chapter explains the basic principle of the instrument, shows how it is structured and gives a
functional description of the assemblies.
The KjelMaster K-375 is dedicated to Kjeldahl and Devarda nitrogen deter mination including potentiometric or colorimetric titration.
Automation of Kjeldahl determination is possible with the KjelSampler K-376 / K-377.
4.1 Device overview
1
KjelMaster K-375
2
KjelSampler K-376
3
Protective shield
4
Rack with sample tubes
5
Handle for protective shield
6
Transfer hose
7
Splash protector
8
Sample tube bracket
9
Sample tube
10
Protective door
11
Condenser
12
Receiving vessel
13
Touch screen with display
14
pH electrode or optical sensor
15
Service door
16
External buret
Fig. 4.1: Device overview
NOTE
The main switch of each device can be found on the rear right side of the housing.
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4.1.1 Opening the service door
The service door is secured with a sensor/switch: Electrical power is disconnected immediately when
the service door is opened, thus preventing electrical shock during maintenance.
To open the the service door for maintenance proceed as follows:
To open the service door,
∙ pull the door lock
1
upwards
∙ open the door
2
Fig. 4.2: Opening the service door
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4.2 Functional principle of KjelMaster System
K-375 / K-376 / K-377
1
K-376 / K-377
2
K-375
3
Sample tube
4
Dip tube
5
Splash protector
6
Steam generator
7
Condenser
8
Distillate outlet tube
9
Receiving vessel
Fig. 4.3: Functional principle of the K-375 with K-376 or K-377
The sampler arm with dip tube is positioned in a sample tube in the K-376 / K-377. The steam
generator of the K-375 generates steam which is led into the sample tube in the K-376 / K-377 via the
steam hose.
The steam presses the sample into the dip tube, so that the sample is transferred into the sample
tube in the K-375 via the transfer hose.
Water and sodium hydroxide is dosed into the sample tube in the K-375. Then steam is introduced
to drive out ammonia. The ammonia evaporates into the splash protector and condensates in the
condenser.
Boric acid is dosed into the receiving vessel, where the condensated ammonia is collected and finally
titrated.
During the entire distillation process, steam is transferred via the sample tube of the K-376 / K-377 to
the sample tube of the K-375, thus ensuring a thorough cleaning of the sample tube and the transfer
hose.
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Fig. 4.4: Sample transfer principle
Fig. 4.5: Steam transfer during distillation
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4.3 Standby function
Press the key READY to start heating the steam generator.
Press the key STANDBY to stop heating the steam
generator.
Fig. 4.6: Status view
After 30 minutes without operation, the heating of the steam generator is automatically turned off.
In this case „Standby“ is displayed on the Status view.
To activate the device press the READY key. The steam generator will need 120 seconds for heating
up to the operating temperature.
4.4 System preparation
4.4.1 Preheating
The glass parts of the distillation system have to be preheated prior to analysis. This is done by
means of a clean and empty sample tube. It is recommended to perform a preheating, when the
glass (splash protector) has cooled down. The preheating time is predefined and can not be adapted.
4.4.2 Priming
Priming is used to prepare the entire system. This preparation procedure includes distillation and
titration with a clean and empty sample tube. It is recommended to perform a priming at least once a
day, before starting analysis. The priming method can be modified.
4.4.3 Cleaning
At the end of a day, the system should be rinsed thoroughly by performing a cleaning procedure. The
splash protector and the condenser are rinsed with water to remove sodium hydroxide residues. With
regular cleaning, the lifetime of the glass parts is extended. The cleaning method is predefined, but
should be modified and adapted to the size of the sample tube.
4.4.4 Aspiration
With this procedure residues in the sample tube and in the receiving vessel can be aspirated.
For more details see also chapter “6.6.1 System preparation”.
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4.5 Distillation and titration
4.5.1 Distillation and Titration Options
Titration
type
Titration
mode
Distallation
mode
Measuring mode Titration
algorithm
Boric acid
Back titration
Standard
Online
IntelliDist
Fixed time
Endpoint pH
Startpoint pH
Setpoint mV
Optimal
Normal
Potentiometric x x x x x x x x
x
x
Colorimetric x x x x x
x
x
4.5.2 Distillation Mode
Automatic – IntelliDist
This mode eliminates errors caused by a cooled instrument. The countdown of the set distillation time
only starts after operating temperature is attained. With single samples or sample list measurements
this mode guarantees result accuracy from the very first run.
Fixed Time
The countdown of the set distillation time starts immediately with the start of the distillation process.
This setting is recommended when a sample changer is used for the analysis of samples in a rack (or
sequence).
4.5.3 Titration Type
The built-in titrator is fully controlled via the K-375 software. It is not possible to use the titrator without
the KjelMaster K-375. It can be used for boric acid or back titration. The measuring mode can be
determined as endpoint or startpoint titration by defining the method in the K-375. The software of the
K-375 allows to choose between standard and online titration.
Boric Acid Titration
Boric acid adjusted to a pH of 4.65 is used as receiving solution to capture the nitrogen carried over
as ammonia during the steam distillation. The subsequent endpoint titration (pH 4.65) is performed
with an acid titration solution. This titration type does not require an accurate dosage of the boric
acid.
Back Titration
The receiving solution is a standardized acid (e.g. H2SO4) of which an accurate volume is dispensed
into the receiving vessel. After collecting the ammonia the excess acid is titrated with a basic titration
solution (NaOH) at pH 7.00. If the use of boric acid has to be avoided the back titration is the procedure of choice.
4.5.4 Sensor Type
Potentiometric
Potentiometric pH measurement is commonly used and allows both boric acid and back titrations.
They need regular calibration with buffers.
Colorimetric
Colorimetric titration is based on colour change at the equivalence point and is used in situations
where an official standard requires it. For sound measurements and reproducible results the condensate outlet with air bubble trap must be fitted. The condensate outlet prevents air bubbles interfering
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with the measurement. Colorimetric titration requires daily determination of the setpoint.
4.5.5 Titration Mode
Standard
In the standard mode the distillation and titration are performed sequentially. First the distillation is
completed then the titration starts.
Online
In the online mode the titration starts while the distillation is still in progress. The start time of the
titration depends on the pH value and is determined automatically. It helps optimize the speed of
measurements as it saves time.
4.5.6 Measuring Mode
Startpoint pH
The device measures the pH of the boric acid before the distillation is started and uses it later on as
enpoint for the titration. When startpoint titration is used, the pH must not be adjusted to 4.65, but it
must be between 4.4 and 5.0.
Endpoint pH
The set value, normally 4.65, is used as endpoint for the titration. The boric acid has to be adjusted
to pH 4.65 before starting sample measurements. This mode is more accurate and yields the highest
accuracy.
Setpoint mV (colorimetric)
The setpoint must be determined daily before the blank values and samples are colorimetrically
tested, and in addition, if the distillation time, the boric acid, the indicator or the titrant is changed. The
setpoint determined is then used as the end point for the subsequent colorimetric titrations.
4.5.7 Titration Algorithm
Normal
This algorithm is the most accurate one and is recommended for samples with low nitrogen content
(below 1 mg) and for the use of highly-concentrated titration solutions (e.g. 0.5 N acids).
Optimal
The best ratio between accuracy and process speed is achieved with this algorithm.
4.5.8 Determination Mode
Standard
In the majority of cases it is necessary to digest samples to make the nitrogen accessible to steam
distillation. Whenever digested samples are analyzed the standard determination mode is used.
Direct Distillation
A small number of applications allow freeing the nitrogen via direct steam distillation without requiring
a digestion. In such a case the direct distillation mode needs to be activated.
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4.6 Different methods
BUCHI standard methods are stored in the instrument. All BUCHI methods are “read only“, but it is
possible to copy and save them under a different name as an editable customer method.
All methods are listed in alphabetical order, customer methods are first, followed by the “read only”
BUCHI methods (marked with a small yellow lock).
Fig. 4.7: Methods screen
4.7 Blank values
The K-375 differentiates between blanks and control blanks. Blanks are performed to correct minimal
contamination of chemicals on sample determination (sample and reference substance).
Control blanks are performed to check the determination process for cross contaminations and are
not used for calculation.
The determination and the definition of blank values is described in chapter 6 Operation.
4.7.1 Blanks
It is recommended to run blank values with exactly the same method as the subsequent samples.
The blank values may vary, depending on the receiver solution (e.g. concentration of the boric acid,
amount of indicator added, pH value set), the concentration of the titration solution, and the purity of
chemicals.
It is recommended to perform blank values, if:
∙ Fresh chemicals are used or
∙ Before starting determination in order to check the system.
If a blank value is activated for calculation, it remains active, until another blank value is activated.
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4.7.2 Control blanks
A control blank enables to check for cross contamination, e.g. in the middle of a rack, without
affecting the calculation of the following samples.
Example:
Determination of
3 blanks, 6 samples, 1 control blank, 10 samples in a 20-position rack.
All samples are calculated with the mean value of blank 1-3. The control blank allows to check the
system without interruption.
Fig. 4.8: Example of rack containing a control blank
4.8 Reference substances
Reference substances are substances with known nitrogen content and serve to check the performance of the system and the application.
It is recommended to analyze reference substances regularly. For information on reference
substances, see table.
A check of the K-375 without digestion is done with a standardized ammonium salt (e.g. ammonium
di-hydrogen phosphate).
In order to check the entire Kjeldahl process (including digestion), standardized amino acids are used
(e. g. Gl ycine).
The determination of reference substances is done like a normal sample determination (Sample type:
“Reference substance”) as single sample, sample list or a sequence. See Chapter “6.6 Determination”
for details.
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Reference Substances
Name Purity *Commer-
cially
available
purity
% N theoretical
(100%
purity)
Recommended
sample
size
Recommended
titrant concentration
Digestion
necessary
Ammonium
dihydrogen
phosphate
100 99.5 12.18 0.2 g 0.2 N No
Glycine 100 99.7 18.66 0.2 g 0.2 N Yes
Phenylalanine
100 99.0 8.47 0.3 g 0.2 N Yes
Ammonium
sulfate
100 99.5 21.21 0.1 g 0.2 N No
Tryptophan 100 99.0 13.72 0.2 g 0.2 N Ye s
Acetanilide 100 99.0 10.36 0.2 g 0.2 N Yes
* this is only a guideline; please verify and use your specific purity of the reference substance. Therefore, check the respective “Certificate of Analysis” which is delivered from the manufacturer of the
reference substance and create a modified reference substance according to it.
4.9 Indicator for colorimetric titration
To detect the endpoint during a colorimetric titration an indicator must be added to the boric acid. For
optimal performance the Sher mixed indicator is recommended.
The point of inflection is depending on the indicator type as well as on the added indicator amount.
The Sher indicator shows best performance in terms of endpoint detection speed and reliability.
In boric acid the color changes from green (pH >7.6) to blue (7.4 to 4.8) and finally to the gray endpoint
(pH 4.6).
The optimal ratio of the Sher indicator to boric acid is 2.5 mL per 1 L boric acid.
NOTE:
Even the slightest changes to the ratio can result in incorrect end point determination. As an alternative, methyl red/bromocresol green mix indicator can also be used. Ready-made, premixed boric acid
solutions for both indicator options can be obtained from Buchi.
4.10 Result Groups
Each result of a sample determination can be assigned to a group, e.g. the results of samples taken
from the same batch/lot, place, at the same day, etc. can be assigned to the same result group.
All results in the same group are treated the same way regarding sample printout and export of data.
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4.11 Explanation of alkaline direct distillation
As an example, the protein content in milk samples can be determined by direct distillation. This quick
method is based on the fact that milk releases ammonia when boiled in an alkaline solution. Most of
this ammonia is produced by the rapid hydrolysis of proteins containing glutamine and asparagine.
This decomposition is completed within a few minutes. An additional quantity of ammonia, although
small, is released through the complete transformation of other amino-acids. This second reaction occurs very slowly however, and does not interfere with the quick method. This fact permits
an experimental determination of the ratio of total nitrogen or protein to ammonia nitrogen which is
released by boiling in an alkaline solution. Once the resulting conversion factor is determined, a series
of analysis can be carried out for control purposes without the time-consuming digestion step. The
overall analysis is reduced to the following steps:
∙ Sample addition
∙ Dilution
∙ Alkalisation
∙ Distillation
∙ Titration
∙ Calculation
A determination can be completed in approx. 10 minutes according to this procedure. All working
conditions chosen for the experimental determination of the conversion factor must be strictly
adhered to during sample measurements.
For details on the application procedure, please contact your local BUCHI representative.
Determination of the conversion factor and the regression factor:
Fig. 4.8: Example of factor calculation
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Factors of above Example
Conversion Factor = 0.7787; Regression Factor = -0.055.
NOTE
Milk samples with a reduced protein content are obtained by dilution with distilled water.
Calculation:
Calculation of the protein content after factor determination.
g protein/100mL = (Vsample-Vblank )xConv. Fact.+Reg. Fact.
Vsample = Volume Titrant for sample determination in mL
Vblank = Volume Titrant for blank determination in mL
Conv. Fact. = Conversion factor for direct distillation
Reg. Fact. = Regression factor for direct distillation
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5 Putting into operation
This chapter describes how the device is installed and gives instructions on initial startup.
NOTE
Inspect the device for damages during unpacking. If necessary, prepare a status report immediately
to inform the postal company, railway company or transportation company.
Keep the original packaging for future transportation.
!
CAUTION
Heavy weight, avoid overexertion.
∙ Due to the heavy weight of the devices at least two people are required for
taking the KjelMaster K-375 or the KjelSamplers K-376 out of their corresponding packaging. Watch your fingers when putting the device down.
∙ For the K-377 at least three people are required for taking the device out of the
corresponding packaging. Watch your fingers when putting the device down.
5.1 Installation site
The device must be set-up on a stable, clean and level surface.
For safety reasons the distance between the back of the device and the wall or to another object
must be at least 30 cm. No containers, chemicals or other objects must be located behind the instrument.
The KjelSampler K-376 or K-377 is set-up on the left side of the KjelMaster K-375 with a space of
approximate 10 cm. Make sure that the back of the KjelSampler is not in contact with anything, e.g.
hoses, etc.
All devices must be set up in such a way that the main switches and the mains plugs are easily
accessible at all times.
NOTICE
Risk of device damage.
∙ The sampler arm of the KjelSampler K-376 / K-377 must have enough space in
height for movement.
!
CAUTION
Heavy weight, avoid overexertion.
∙ At least two people are required for carrying the KjelSampler K-376 or the Kjel-
Master K-375 due to the heavy weight of the devices. Watch your fingers when
putting the devices down.
∙ At least three people are required for carrying the KjelSampler K-377 due to the
heavy weight of the device. Watch your fingers when putting the device down.
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5.2 Electrical connections
5.2.1 Connections of the KjelMaster K-375
a Power connection K-375
b RS232 connection to K-376 /
K-377
c RS232 connection to balance
d LAN connection
e USB connection to printer
f USB connection for bar code
reader
g Connectors for level sensors
h Fuses (2 x 10A)
i Connector for dosing unit (Acid)
j Connector for additional dosing unit (Base)
k Additional USB-ports
l Connectors for colorimetric sensor (Ind. and Pwr. Col.) or pH
electrode (Ind. only)
m Connectors for temperature sensor
Fig. 5.1: Electrical connections of the K-375
NOTICE
Risk of device damage by wrong voltage.
∙ Make sure that the voltage on the socket corresponds to the voltage given on
the type plate of the instrument.
∙ Always connect the device to an earthed socket. External connections and
extension cables must be provided with an earthed conductor lead (3-pole
couplings, cable or plug equipment) as the mains lead has a molded plug, thus
avoiding risks due to inadvertent defective wiring.
∙ Make sure that no electric sparks form in the device or its surroundings as they
might damage the instrument.
On the KjelMaster K-375
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∙ Connect the power cable to the power connection 1.
∙ Connect the level sensors to the corresponding connectors 7.
NOTE
Unlike the level sensors for the storage tanks of H20, NaOH and H3BO3, the presence of the level
sensors for the waste containers has to be indicated within the software! (See section “Peripherals”
in chapter 6.9.1)
∙ Connect the dosing unit for the acid to connector 9.
∙ Connect the RS232 cable to the sampler (if present) to the corresponding connector 2.
∙ Connect any additional peripherals according to the description in figure 5.1.
5.2.2 Connections of the K-376 / K-377
(left rear side of the housing)
(right rear side of the housing)
1
Power switch K-376 / K-377
2
Power connection K-376 / K-377
3
Fuses (2 x 3A)
4
RS232 connection to K-375
5
Toggle switch (see chapter 8.3)
Fig. 5.2: Electrical connections of the K-376 / K-377
NOTICE
Risk of device damage by wrong voltage.
∙ Make sure that the voltage on the socket corresponds to the voltage given on
the type plate of the instrument.
∙ Always connect the device to an earthed socket. External connections and
extension cables must be provided with an earthed conductor lead (3-pole
couplings, cable or plug equipment) as the mains lead has a molded plug, thus
avoiding risks due to inadvertent defective wiring.
∙ Make sure that no electric sparks form in the device or its surroundings as they
might damage the instrument.
On the KjelSampler K-376 / K-377
∙ Connect the power cable to the power connection
2
∙ Connect the cable to the K-375 device to the RS232 connector
4
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5.3 Transfer connection K-376 / K-377 to K-375
The transfer connection between the K-375 and the K-376 or K-377 sampler consists of two hoses,
the white transfer hose and the red steam hose.
Both hoses have to be connected to the K-375 as well as to the sampler (K-376 or K-377) and
secured with hose clamps. The K-376 is delivered with both hoses premounted to the device.
!
WARNING
Serious chemical burns by corrosives. Risk of burns by hot steam.
∙ Never operate the K-375 together with a sampler while the sample transfer and
steam hoses are missing, defective, or incorrectly mounted.
∙ Make sure there is always enough room for a free movement of the sampler
arm – if the sampler arm collides with any object during movement, the transfer
hose and/or the steam hose may break!
5.3.1 Connecting the K-376 to the K-375
∙ Fix the transfer hose support
1
with the
screw on the valve 2 on the rear side of the
K-375.
∙ Guide both hoses 3 and
4
through the
transfer hose support.
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Fixing the transfer hose to the K-375
Mount the white transfer hose on the valve of the
K-375 (top right corner):
∙ Unscrew the screw cap 3 from the screw
connection of the valve
1
(attention: 2
parts) and take out the cutting ring 2.
∙ Slide the screw cap over the white hose 4.
∙ Slide the cutting ring over the hose.
∙ Plug the hose on the valve and fix it by
screwing the screw cap on the valve.
Fixing the steam hose to the K-375
Mount the red steam hose on the steam valve of
the K-375 (top right corner):
∙ Slide the red hose on the connector and
secure it with a hose clamp.
Fig. 5.4: Connection to the K-375
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Connect the K-375 and the K-376 / K-377 with the corresponding/delivered RS232 cable (crossed)
∙ K-375: See b in picture 5.1
∙ K-376 / K-377: see d in picture 5.2
!
WARNING
Risk of burns by hot steam.
∙ Make sure to place a sample tube in the washing position(s) of the sampler.
Place an empty sample tube into the washing position of the sampler:
The washing position is on the rear right side of the tray.
For the K-376 this is the fixed position to the right of the express rack.
The K-377 provides two washing positions – one on the rear right side of each tray.
5.3.2 Connecting the transfer hoses of the K-377
K-377
∙ Connect the transfer hose and the steam
hose to the two fittings on top of the sealing
cap on the sampler arm. Secure both
connections with hose clamps 1.
∙ The red steam hose has to be fixed to the
first position (marked with a red ring) –
pointing to the front of the instrument!
∙ Fix the plastic cable channel with the two
provided screws 2 on the sampler arm.
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On the K-375
∙ Remove the tightening screw from the holder
on the valve 1.
(The screw is not required for connection to
K-377)
∙ Slide the ring of the chain fastener onto the
holder on the valve 1 and fix it by tightening
the threaded bar.
∙ Slide the the plastic holder of the transfer
connection onto the threaded bar 2. Hold it in
place by screwing the second nut hand-tight
on top.
∙ Mount the white transfer hose on the valve
using the provided screw connection 3.
∙ Mount the red steam hose on the steam valve
and secure it with a hose clamp 4.
5.4 Reagent/water and waste connections
NOTICE
Risk of device damage by exceeding the maximum permissible pressure for the
cooling water inlet.
∙ Make sure never to exceed the maximum permissible pressure of 6 bar for the
cooling water inlet.
!
WARNING
Serious chemical burns by corrosives.
∙ Make sure that the tanks are connected correctly. If the wrong tank (e. g.
reagent tank containing NaOH) is connected to the pump labelled as „H2O”,
NaOH might be dosed while H2O is expected.
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a H2O pump (for steam generator and sample
tube)
b Boric acid (H3BO3) pump
c NaOH pump
d Waste outlet (receiver waste)
e Waste outlet (sample tube waste)
f Cooling water outlet
g Cooling water inlet
Fig. 5.5: Reagent, water and waste connections
NOTE:
All pumps are self-priming, no overpressure is necessary at the tanks!
If the sample tube waste and the receiver waste shall be collected in the same tank, the Y-piece
(contained in the standard delivery) can be used to merge both tubes.
Cooling water connection
Screw the cooling water hose to the cooling water inlet on the device side and connect it to the water
supply. The water pressure should not exceed 4 bar and the cooling water temperature should not
exceed 25 °C. The flanged screw coupling for the water connection has a standard screw thread of G
3
/4“.
Drain cooling water
Place the drain hose for the cooling water directly into the drain (sink). For this purpose, shorten the
silicone hose to the optimal length.
Make sure that the drain hose has no kinks and sharp bends.
Secure the drain hose to avoid any flooding inside or in the vicinity of the instrument.
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Waste/aspiration hoses
The sample residue can be aspirated and collected
separately from the receiver waste. For this purpose a
separate collection tank is necessary. For joint disposal
of the sample tube and the receiver waste the delivered
y-piece is used to guide the two hoses into one hose. All
connections must be secured by clamps.
Fig. 5.6: Guidance of the two outlets into one hose
The collection tank must be located lower than the
device to guarantee proper drainage.
Connect the waste hose to the waste outlets and secure
them with clamps. The hose must be cut to appropriate
length. The drain hose is then connected to the tank,
by means of the straight connector and the screw cap
including the sealing.
Alternatively the waste hose can also be guided into the
sink.
Fig. 5.7: Connection of the drain hose using the
straight connector
!
WARNING
Risks and hazards for humans, animals and the environment.
∙ Make sure to carefully collect any residues that may be hazardous to humans,
animals or the environment and to dispose them according to your local laws
and regulations.
5.5 Buret unit for titrant
The preinstalled tube for the titrant
2
is reaching out of
the housing and must be connected to the dosing unit
at port “1”.
Fig. 5.8: Connection of the FEP hose at the dosing
unit
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The bottle containing the titration solution can be fixed
on the right side of the device using the provided strap
1
.
The buret (consisting of the dosing unit and the
corresponding drive unit) is mounted on the bottle.
Fig. 5.9: Buret mounted on the titration solution
bottle
The cable of the driving motor is guided through a cut-out in the housing at the rear side of the K-375
and must be connected to port “Acid” (see chapter 5.2.1).
Fig. 5.10: Guidance of the cable through the cut-out Fig. 5.11: Connection of the cable of the driving motor
The cable of an additional dosing unit for back titration can also be guided through the same cut-outs
in the housing.
NOTE
In case the buret gets blocked, refer to chapter 7.7.6 “Troubleshooting the dosing unit”. The
assembly of the dosing unit is explained in detail in the separate operating instructions delivered
together with the dosing unit.
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5.6 Positioning of the dosing tip
Mount the spacer onto the titrant dosing tip to adjust the positioning of the outlet and place it in the
receiving vessel. It should be positioned in the same height as the stirrer.
Fig. 5.12: Mounting of the spacer at the dosing tip
NOTE
The dosing tip must not touch the bottom of the receiving vessel, as this would block the outlet.
5.7 Storage tank connection
To connect the storage tanks, proceed as follows:
∙ Cut the Nylflex tube into pieces to the appropriate length.
∙ Insert a PTFE suction tube into the Nylflex tube.
∙ Push a EPDM sealing ring over the Nylflex tube.
∙ Now fasten the tubes to the tank with the red screw cover.
The storage tanks should not be positioned higher than the device itself and not lower than
1 meter below the instrument.
Fig. 5.13: Tank connection
All pumps are self-priming, no overpressure is necessary at the tanks.
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NOTICE
Risk of device damage by calciferous water or wrong rong connected tanks.
∙ Use only distilled water for the H2O storage tank to keep the steam generator
maintenance-free.
∙ Make sure that the tanks are connected correctly. If the wrong tank (e. g.
reagent tank containing NaOH) is connected to the pump labelled as „H2O“, the
steam generator will get damaged.
5.8 Level sensors
Four capacitive level sensors are contained in the standard delivery of the instrument. Three are
intended for the storage tanks (NaOH, H3BO3 and water) and one for the waste collection tank (either
the sample tube or receiver waste). Additional level sensors are available as optional equipment. Each
individual sensor is connected to the corresponding socket on the rear side of the device (see section
5.2.1).
The sensitivity of the capacitive level sensors can be adjusted to safely detect the liquid level, if necessary.
Assemble the level sensors according to the following picture:
Fig. 5.14: Assembly of the level sensors
∙ Mount the sensor at the tank using the provided O-ring (see 1 in figure 5.9) and connect it at
the rear-side of the device to the corresponding port (NaOH, H2O, H3BO3, Waste Sample Tube,
Waste Receiver, or Titrant). The sensitive side of the sensor (marked with the crosshair)
has to face the tank!
∙ Make sure the tank is filled with the corresponding liquid.
∙ Shift the sensor together with the rubber strap until it is located below the liquid level.
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∙ The red LED at the sensor should now be off.
∙ If the sensor does not safely detect the liquid:
Use a small screwdriver to set the sensitivity (with the small adjustment screw) of the sensor (see
2
in figure 5.9).
Front view:
Rear view: The crosshair marks the sensitive area
Status LED
Adjustment screw
b
Fig. 5.15: Fixing the level sensors
NOTE
The sensor detects a liquid when the red LED is off.
The level sensor for the waste tank must be set active within the Settings Peripherals screen (See
chapter “6.9.1 Settings“). This is not necessary for the other sensors.
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5.9 Installation of the titration sensor
Connect the sensor to the cable already mounted.
Fig. 5.16: Connection of the sensor
5.9.1 Potentiometric sensor
Remove the pH electrode from the storage cap and insert it into the receiving vessel. The spacer is
used to adjust the positioning. The electrode must not touch the bottom of the receiving vessel, as
this could lead to glass breakage. The ideal positioning is 1-2 mm above the bottom of the receiving
vessel.
NOTICE
Risk of sensor damage by pushing the electrode with too much pressure onto the bottom of the
receiving vessel.
Risk of sensor damage by wrong storage.
Always store the pH electrode in the storage cap in saturated KCl solution (4.2 mol/L). A pH electrode should not be stored dry as this would destroy the diaphragm. If a pH electrode has been
stored dry, let it regenerate in saturated KCl for 24 hours or at least overnight prior to further use.
5.9.2 Colorimetric sensor
Fig. 5.17: Colorimetric titration setup
Fit the air bubble trap on the condensate outlet. The wavelength must be adjusted on the optical
sensor according to the indicator (Sher: 610nm, bromocresol/methyl red: 640nm); this can be done
with a permanent magnet (magnetic mixing rod) on the sensor probe. Clean the optical sensor before
use and construct the test setup according to the technical note (335/2018) available on the BUCHI
website.
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5.10 Connections to peripheral devices
The following devices and accessories can be connected to the K-375:
∙ up to 6 level sensors for monitoring the liquid level in storage or waste tanks
∙ a printer (via USB port) for printing e.g. results or methods
∙ a network cable (LAN) for storing data on a network or for communication with the optional
available PC software KjelLink
∙ a sampler K-376 / K-377 for automatic determinations of sample sequences
∙ a balance for the automatic acquisition of the sample weight
∙ a bar code reader for capturing sample data like IDs or batch numbers
∙ an additional external dosing unit for back titration
5.10.1 Connecting a printer
The K-375 supports printers with USB port and language PCL 3 or higher (PCL 5e, PCL 6, PCL 7 etc.
e.g. from Hewlett Packard).
The printer is connected to the USB port marked with “Printer” (position
5
in Fig. 5.1).
If the K-375 is connected to the network, it is also possible to use a network printer.
NOTE
For using the printer make sure to switch on the printer first, followed by the K-375.
5.10.2 Connecting a network cable
Instead of storing data locally on the instrument, it can also be stored on a network place. A network
cable can be connected to the device on the LAN port on the rear side. For adapting the network
settings refer to chapter “6.9.1 Settings Netw o rk”.
More details regarding the network connection can be found in the document KjelMaster K-375 Manual - Network Connection, which can be obtained from any authorized BUCHI representative.
5.10.3 Connecting a KjelSampler K-376 or K-377
Connect the KjelSampler K-376 or K-377 to the KjelMaster K-375 by means of the supplied RS232
cable.
5.10.4 Connecting a balance
The connected balance must fulfill the following criteria:
∙ The balance must be equipped with an RS232 interface and a „print“-button. Otherwise it is not
possible to send sample weights to the K-375.
∙ The RS232 settings of the balance and the K-375 software must correspond.
∙ The sent command from the balance must have the following string: floating point_unit.
The weight is transferred to and stored in the K-375. Negative values are automatically converted into
positive sample weights.
For the configuration of the balance refer to Settings Peripherals screen (See chapter “6.9.1
Settings“).
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5.10.5 Connecting a bar code reader
A USB barcode reader can be used to read in data, e.g. a sample name or the weight of a sample,
that is printed in form of a barcode. The barcode reader can be connected to the corresponding USB
connector on the rear side of the K-375. (See chapter 5.2.1 “Connections of the K-375”.)
5.10.6 External dosing unit for back titration
The external dosing unit is connected to the port “Base” on the rear side of the instrument. (See position
10
in figure 5.1) . For installation and assembly of the dosing unit, refer to the instruction manual
of the dosing unit.
NOTE
For optimum performance and minimal fluctuation of the measured values, the dosing tip of the
dosing unit with the titrant always has to be placed in position “TITR” of the receiver. The second
dosing tip can be placed in any other position!
5.11 Preparing the system
5.11.1 Preparing the software
In general it is recommended to check and adapt all device settings, located under
HOME Settings
previous to the first use of the instrument.
Following a selection of the most common settings to be adapted is provided:
Define regional settings
HOME Settings Regional settings
Choose device language, keyboard layout, and date and time format
Set date and time
HOME Settings Date and time
Set date, time, and time zone
Define user (optional)
HOME Settings User administration
Different users with specific user rights can be defined. As long as no user is defined, no user administration will be used. For more details refer to the section “6.3 User concept”.
Check peripherals
HOME Settings Peripherals
Make sure all connected peripherals are selected and configured.
Specify an import and export path for results and other data
HOME Settings Import and Export
Data can be exported either to a USB device or to a network data share. If a network data share shall
be used, a path needs to be specified.
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Depending on your preferred applications and methods the following items have to be defined:
Volumetric solutions
HOME Volumetric Solutions
Define all solutions that may be used for your applications.
Reference substances (optional)
HOME Reference Substances
Specify the reference substances together with their theoretical values.
Method (optional)
HOME Methods
Define a new determination method or modify an existing method if necessary.
Blank Corrections
HOME Blank Correction
Determine the general behavior of the system with respect to the blank correction.
5.11.2 Preparing the hardware
There are only a few tasks that have to be performed in order to prepare the hardware for the first
use:
Calibrate the pumps for H2O, H3BO3 and NaOH
HOME System Preparation Pump calibration
∙ Select the pump to be calibrated (H2O, NaOH or H3BO3).
∙ Enter the target “Dose volume”, e.g. 50mL.
∙ Press START to start the calibration procedure.
∙ Measure the actually dosed volume and enter it as calibration volume in the displayed screen.
Repeat the calibration procedure, until the measured and the dosed volume correspond.
∙ An acceptable difference at 50mL is ±5mL.
NOTE
H2O and NaOH can be dosed into the sample tube and then poured for measurement into a graduated cylinder.
The H3BO3 can be dosed directly into the receiving vessel and then poured into a graduated
cylinder.
Rinsing of the buret and the titration hoses
HOME System Preparation Buret functions Dose
Dose some liquid to a waste vessel to rinse the buret and the titration hoses. Repeat the rinsing, until
the whole buret and all the titration hoses are filled with titration solution. Make sure there are no air
bubbles in the buret or in the titration hoses.
Calibration of pH electrode
HOME System Preparation Calibration pH electrode
Calibrate the pH electrode by following the instructions on the screen (see chapter 6.6.1).
NOTE
We recommend to calibrate the pH electrode regularly (e.g. every day) with buffer solution pH 4 and
pH 7.
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6 Operation
This chapter gives examples of typical device applications and instructions on how to operate the
device properly and safely.
!
CAUTION
Risk of injury.
Never operate the device with damaged glassware.
6.1 The operating principle
The graphical user interface of the K-375 is operated via the touch screen. To select a button or
an input element in the dialog window, you simply touch the screen using a soft blunt object or a
fingertip.
!
CAUTION
Risk of injury.
∙ Never touch the surface of the touchscreen with pointed or sharp objects!
Otherwise the screen might get damaged and splinter.
6.2 The home screen
The central element of the user interface is the home screen:
Fig. 6.1: The home screen
The home screen contains 4 different areas with buttons leading to the corresponding dialog
windows:
Functional
area
Icon Dialog window Description
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Determination
All tasks
related to
the sample
measurement
itself (System
preparation
and sample
definition)
System Preparation
and manual operation
Perform all tasks related to the preparation of the
system, like Preheating, Priming, Cleaning, Aspiration,
periodic tasks like electrode calibration or manual
tasks related to burets, pumps, and a sampler.
Single Sample Determine a single sample based on Type, Name,
Method,and (Result-)Group. (Plus additional parameters depending on the sample type.)
Sample Lists Create a sample list – a list of samples to be deter-
mined one by one without an auto sampler.
Sequences Create a sample sequence with predefined samples
per rack to be processed using an auto sampler.
(Only visible if an auto sampler has been configured
under “Settings”.)
Results
All tasks
related to
the results of
the system
(storage,
viewing,
printing and
selection)
Result Groups Create and view groups for the storage of your
results.
Last Results View, print or export the results of the last sample
determinations.
Blank Correction Calculate mean blanks, enter manual blanks or
adapt the settings for the correction of blanks.
Determination
Parameters
All tasks
related to
the methods
and the used
solutions and
substances.
Methods Create, import, edit, and manage your determination
methods.
Volumetric Solutions Manage all used volumetric solutions.
Reference
Substances
Manage all used reference substances.
Device
All tasks
related to the
device itself.
(Settings,
Utilities and
Diagnostics)
Settings Adapt all device settings, like date and time,
network settings, peripherals, and user management.
Utilities Set your backup path for the database backup, use
the lab timer or switch to the demo mode of the
instrument.
Diagnostics Switch to service mode and view or check all
relevant system components.
Logout Login/Logout to the instrument. (Only visible if User
management is used.)
By pressing the HOME button on the bottom of each screen you can return to the home screen from
any other screen.
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6.2.1 The title bar
The title bar is present on top of any screen and consists of the following components:
Fig. 6.2 Title bar
1 Icon of the current dialog
2 Title of the current dialog
3 System status icon
4 Options, hints or help for the current screen
5 Date & Time
6.2.2 The bottom bar
Like the title bar, the bottom bar is always present on any screen. It consists of 5 different buttons,
whose function will never change (there is one exception: the STA R T button will be switched to a
PAUSE button during a running sequence):
Fig. 6.3 Bottom bar
1 HOME – this button will bring you back to the home screen from any other screen
2 SHOW/HIDE STATUS – shows or hides the Status view
3 READY/STANDBY – toggles the system mode between standby and ready. In standby mode the
steam generator is powered off for energy saving reasons.
4 START/PAUSE – starts a task, or pause a running sequence
5 STOP – stops a task.
This button also acts as an EMERGENCY STOP switch. If the device malfunctions or there is an
operating error, you can stop all current tasks by pressing the STOP button. (The current will be
switched off, resulting in the closure of all valves.)
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6.2.3 System status icons
Icon
Meaning
The device is ready without any restrictions.
A sample determination/task can be started.
A task is running (Determination, Preheating, Cleaning etc.)
A sample determination/task can’t be started.
A warning message is shown under Status/Info.
Check Status/Info before starting a task. Depending on the cause for the warning, the start
button may be inactive.
There are errors that have to be remedied before a determination can be started (e.g. titrator
not ready, dosing unit not connected etc.)
The device is in standby mode (steam generator switched off, power save mode)
– Press READY to return to operating mode.
Serious error – contact BUCHI service.
Warnings and info messages can be viewed in the INFO section of the status view. (Accessible via
the button SHOW/HIDE STATUS in the bottom bar.)
6.3 User concept
The software distinguishes between three user types with differing access permissions: Administrator
(no restrictions), Operator (limited permissions), Lab Manager (limited permissions). Find the detailed
user rights in the "KjelMaster K-375: Compliance guide Pharma package" available on the BUCHI
website.
NOTE
In case you forgot the password for your administrator account, you can ask your BUCHI service
center for a password for the BUCHI Administrator. The account of the BUCHI administrator will
always be present on your system and can not be deleted. The password will be valid for one day,
enabling the creation of a new administrator account on your system.
6.4 Editable and non-editable menu items
∙ All menu items with a white background can be viewed, but not edited.
∙ All menu items, displayed with a grey background can be edited or can be clicked to display
further information. A small arrow at the right end of the push button indicates existence of
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further screens.
In the example below the Titer is the only attribute that may be changed by an operator:
Fig. 6.4 Volumetric solutions screen
If an item is editable or not, depends on the rights of the user. All resources that are present by
default (standard methods, volumetric solutions, and reference substances) can not be deleted –
those items are marked with the symbol of a small padlock.
NOTE
Sample lists and sequences can be locked and unlocked by users with administrator rights therefore
the check mark in front of the list or sequence has to be checked and the LOCK button has to be
pressed.
Fig. 6.5 Listed item
1 Check box for selecting an item
2 Padlock – indicates items that can not be deleted
3 Arrow symbol – indicates further screens belonging to the same item
NOTE
To select a larger number of sequenced items proceed as follows:
∙ check the check box of the first item
∙ check the check box of the last item by pressing and holding it, until all items in between
become automatically selected.
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6.5 The status view
The status view of the system is accessible via the SHOW/HIDE STATUS button in the bottom bar:
Fig. 6.6 The status view
1 Buttons for direct dosing of boric acid, sodium hydroxide, and water.
NOTE
The dosed amount per click can be adapted by a user with administrator rights under HOME u
SETTINGS u Dosage volume in status view
2 Buttons for switching between RESULT-, CHART-, and INFO-display.
3 Status field – indicates the system status and shows the active step of the running task.
4 Progress indication for the running task (remaining time, titrated volume, and measured pH)
5 Information area – shows last results with the currently active blank, the determination chart or
system information.
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Colors of the status field
Color of status field Meaning
Green – the system is ready for sample determinations.
Orange – the system is in standby mode. (The steam
generator is powered off.)
Blue – the system is busy (preparative task, periodic
task, or sample determination running).
Red – the system has an error, or a system component
is not ready.
6.5.1 RESULT display
The RESULT display of the Status view shows
the last 3 results and the currently active blank
together with its type and value.
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6.5.2 CHART display
The CHART display of the Status view shows two
charts:
∙ pH versus determination time [s] and
∙ pH versus titrated volume [mL]
NOTE
The charts are only temporarily available and will be
overwritten with the charts of the next performed
determination. They are excluded from the manual
data export. Each result that is exported automatically will always contain the charts.
6.5.3 INFO display
The INFO display of the Status view shows all
system and error messages.
6.6 Determination
In general there are three different ways for a sample determination with the KjelMaster K-375:
∙ Determination of single samples (one by one without a sampler)
∙ Determination of a predefined sample list (one by one without a sampler)
∙ Determination of a complete rack in a predefined sequence (with a KjelSampler K-376 or K-377)
Sample determination possibilities
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Single sample
determination
Sample List
determination
Sequences (automatic
rack determination with
sampler)
Recommended
for:
∙ Only few samples
∙ Express sample
(e. g. interruption of a
group)
∙ Method evaluation
∙ Many samples
(> 10)
∙ Routine analysis
∙ Number of samples
in a list is variable
∙ Determination with
digestion
∙ Many samples (> 20)
∙ Routine analysis
∙ The maximum number
of samples in a rack is
defined ( 4 samples
for the express and
12 respectively 20
samples for the
normal racks)
Operation
procedure:
1. Enter data for the first
sample
2. Determine the first sample
3. Enter data for the second
sample
4. Determine the second
sample
5. ...
1. Enter data for all
samples
2. Determine the first
sample
3. Determine the second
sample
4. ...
1. Enter data for all samples
2. Determine the first
sample
3. Determine the second
sample
4. ...
Description:
Without sampler. Without sampler. With KjelSampler K-376 /
K-377.
NOTE
Pressing the red STOP key on the touchscreen stops all processes immediately.
NOTE
Before starting a sample determination always check the system status icon in the upper right corner
of the display to ensure the device is ready for a determination without any restrictions.
The following icon should be displayed:
Other icons may indicate the necessity of preliminary user interaction to prepare the device or to
solve problems. For details refer to section ”6.2.3 System status icons”.
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6.6.1 System Preparation
Within the area System Preparation all tasks related to the preparation of the system, like Preheating,
Priming, Cleaning, and Aspiration can be defined and performed. In addition periodic tasks like electrode or pump calibration and certain manual tasks related to burets, a sampler, or pH measurement
can be performed.
Preparative Tasks
The System Preparation dialog is subdivided in two
sections:
Preparative Tasks
∙ Preheating
∙ Priming
∙ Cleaning
∙ Aspiration
Periodic Tasks
∙ Calibration pH electrode
∙ Setpoint colorimetric sensor
∙ Buret functions
∙ Pump calibration
∙ Sampler functions
∙ Measuring pH or mV
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Calibration pH electrode
It is recommended to calibrate the electrode
every day before starting sample determinations.
The electrode should be treated according to the
recommendation described in the electrode supplementary sheet.
We recommend replacing the electrode, if it does
not fulfill the following criteria at 25 °C room temperature anymore:
Slope 95 – 105%
Zero point pH 6.4 – 7.6
(For pH electrodes other than the ones supplied by
BUCHI, additional criteria might be important.)
NOTE
It is recommended to use buffer solutions pH 4.00
and 7.00. (For a 3 point calibration in addition the
buffer solution for pH9.21 is recommended.)
Discard buffer solutions after usage. Work with
fresh solutions every day.
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Setpoint colorimetric sensor
It is necessary to determine the Setpoint every day
before starting sample determinations, and when
the method is changed or fresh chemicals are used
to adjust the device to the current conditions.
Before the Setpoint determination a Preheating
should be performed to heat up the system.
We recommend a determination of 3 Setpoint
cycles before a determination is started. The last
Setpoint is used as endpoint for the following determinations.
Select whether the Setpoint cycle should be
performed via the KjelSampler or not and the
number of cycles. Set the concentration of the
boric acid used, the indicator and the method. The
selected method for Setpoint determination must be
identical to the method used for sample determination.
The Setpoint should fulfill the following criteria:
Deviation between the last two Setpoints should not
be more than ±20 mV.
If Sher indicator is used, you should work with a
wavelength of 610nm, in which case the setpoint is
in the range of 300 - 500mV.
If bromocresol green/methyl red indicator is used,
you should work with a wavelength of 640nm, in
which case the setpoint is in the range of 300 500mV.
NOTE
To obtain good results, the optical sensor should be
used with the setup described in Section 7.2.6. To
prevent accumulations of air bubbles on the optical
sensor, clean the optical sensor regularly and keep
it in the wash solution when not in use.
All Setpoint measurements are stored in Result
Groups Setpoint
Method must be identical to the determination
method used for the samples and blanks.
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Preheating
The glass parts of the distillation system have to
be preheated prior to analysis. This is done by
means of a clean and empty sample tube. It is
recommended to perform a preheating, when the
glassware has cooled down. A status message on
the status view will inform the user if preheating is
required.
If an auto sampler is configured under “Settings”,
select either “Unit only” or “Via Sampler” for
“Preheating cycle”.
For “Unit only” only the glassware and tubing of the
K-375 device is heated up. With the option “Via
Sampler” also glassware and tubing of a connected
sampler can be included for the heat-up procedure.
The duration of the preheating procedure (“Distillation
time”) can not be changed.
Press START to start the preheating procedure.
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(screenshot stretched)
Priming
Priming is used to prepare the entire system. This
preparation procedure includes the distillation and
titration with a clean and empty sample tube, as
well as the dosing of chemicals. It is recommended
to perform a priming at least once a day, before
starting analysis. The priming procedure is similar to
a sample determination method and can be modified.
Priming Parameters
Select Yes for “Preheating before priming” if prior to
the priming procedure a preheating procedure shall
be performed.
Set the number of “Priming runs”.
Set “Priming cycle” to “Via sampler”, if the priming
procedure should be performed via a present
sampler. (Only visible if a sampler has been configured under “Settings”.)
The other parameter sets Distillation Parameters,
Titration Parameters, and Aspiration Parameters are just the same like within a method. A
detailed explanation can be found in the section
“6.8.1 Method”.
Press START to start the priming procedure.
Press FACTORY DEFAULTS to reset the settings
of this screen.
NOTE
If only one priming cycle is selected and no aspiration, no aspiration will be done at all.
If more than one priming cycle is selected and no
aspiration, the sample tube and the receiving vessel
will be aspirated between the single priming cycles,
but not after the last cycle has been performed –
instead the system will be stopped after the last
run.
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Cleaning
With regular cleaning, the lifetime of the glass
parts can be extended. Thus it is recommended to
perform a few cleaning runs before switching off the
unit. The cleaning procedure is performed by means
of a distillation with water in a clean sample tube.
Thus all residues from the last sample determination
can be removed.
The volume of water to be used for each cleaning
cycle and the number of cleaning cycles can be
adapted just like the distillation time in seconds.
The steam output can be set between 30 and
100%. In case a sampler is present, the Cleaning
cycle can be enhanced from “Unit only” to “via
sampler” – in this case the hoses from and to the
sampler are also cleaned.
Press START to start the cleaning procedure.
Press FACTORY DEFAULTS to reset the settings
of this screen.
NOTE
If only one cleaning run is selected and no aspiration, no aspiration will be done at all.
If more than one cleaning run is selected and no
aspiration, the sample tube and the receiving vessel
will be aspirated between the single cleaning runs,
but not after the last run has been performed –
instead the system will be stopped after the last
sample.
Aspiration
The aspiration procedure automatically aspirates the
sample tube and/or the receiving vessel. All waste
liquids of both sources can be collected separately.
Select “Yes” to enable automatic aspiration or “No”
to switch of automatic aspiration for the respective
vessel.
Press START to perform the aspiration.
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Buret functions
Select the buret function to be performed:
∙ Prepare,
∙ Discharge, or
∙ Dose
Press START to start the selected buret function.
NOTE
If more than one buret is connected to the instrument, the respective buret unit (Acid or Base) can
also be selected. An additional buret for a base can
be connected to the device (e.g. for back titrations)
and will be detected automatically during power-on
of the instrument.
Pump calibration
Select the pump to be calibrated (H2O, NaOH or
H3BO3).
Enter the target “Dose volume”, e.g. 50mL.
Press START to start the calibration procedure.
Measure the actually dosed volume and enter it as
calibration volume in the displayed screen. Repeat
the calibration procedure, until the measured and
the dosed volume correspond.
An acceptable difference at 50mL is ±5mL.
NOTE
H2O and NaOH can be dosed into the sample
tube and then poured into a graduated cylinder for
measurement.
The H3BO3 can be dosed directly into the receiving
vessel and then poured into a graduated cylinder.
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Sampler functions
The actions “Move to zero position” and “Move to
service position” are available for both sampler types
(1-tray and 2-tray). For a 2-tray sampler the arm is
moved to the corresponding zero or service position
of the tray, the arm is actually positioned in.
For a 2-tray sampler it is also possible to move the
arm of the sampler with “Move to tray A” from tray B
to the zero position of tray A and vice versa.
Press START to move the arm to the selected posi-
tion.
Measuring pH or mV
Using this functionality a direct measurement can
be performed with the potentiometric or colorimetric
sensor.
Select either potentiometric or colorimetric for the
“Sensor type”. Adapt the stirrer speed during the
measurement to your needs.
Press START to start the measurement.
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Single Sample
In general four different kinds of samples can be determined:
∙ Blanks (can be used for the correction of sample results).
∙ Samples
∙ Reference substances (results can be rejected if a reference substance is outside of its
predefined limits)
∙ Control blanks (to be determined for information only – can not be used for any sample
corrections)
The single sample determination is thought for a small amount of samples to be measured without a
sampler present.
First of all the sample type has to be selected:
∙ Blank,
∙ Sample,
∙ Reference substance or
∙ Control blank.
According to the selected type of sample,
different parameters are available:
For samples of type Blank,
press “Name” and enter a name for the blank
result.
Press “Method” and select the method to be
used for the determination of the blank from the
list of the available methods.
Press “Group” and select a result group for the
storage of the result from the list of the available
result groups. (It is also possible to create a new
result group using the New Group button.)
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For samples of type Sample,
press “Name” and enter a name for the sample
result.
Press “Sample weight” and enter the weight of the
sample in [g] or [mL].
Press “Protein factor” and enter the protein factor
for the determination of the results.
Press “Method” and select the method to be used
for the sample determination from the list of the
available methods.
Press “Group” and select a result group for the
storage of the result from the list of the available
result groups. (It is also possible to create a new
result group using the New Group button.)
For samples of type Reference Substance,
press “Name” and enter a name for the result of the
reference substance determination.
Press “Reference substance” and select the reference substance from the list.
Press “Sample weight” and enter the weight of the
sample in [g] or [mL].
Press “Method” and select the method to be used
for the determination of the reference substance
from the list of the available methods.
Press “Group” and select a result group for the
storage of the result from the list of the available
result groups. (It is also possible to create a new
result group using the New Group button.)
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For samples of type Control Blank,
press “Name” and enter a name for the control
blank result.
Press “Method” and select the method to be used
for the determination of the control blank from the
list of the available methods.
Press “Group” and select a result group for the
storage of the result from the list of the available
result groups. (It is also possible to create a new
result group using the New Group button.)
6.6.3 Sample Lists
With the sample list functionality it is possible to predefine a complete list of samples to be determined one by one without a sampler. Each sample list can be filled with any number of predefined
samples. If all samples of a sample list are selected at once for the determination, they will be determined in the same order they were added to the list. It is also possible to determine the samples in a
different order by selecting individual samples from the list.
The type (Blank, Sample, Reference substance or Control blank), and name of each sample can
be chosen freely. The same applies for the used method and the result group for the storage of the
result.
For samples in addition the weight and the protein factor have to be specified. If a compatible balance
is connected to the instrument, the weight of each sample can be automatically taken over from this
balance.
NOTE
For each new sample the entries of the previously entered item are used as default values (the default
value for the name depends on the type of the sample – in this case the name of the last sample of
the same type is taken as default). All default values can be overwritten.
To start a sample list determination you have to enter the list and to select the samples to be determined. To select a complete list simply check the check box in front of the first sample and check and
hold the check mark in front of the last sample in the list or use SELECT ALL. As a result all samples
in between will also be checked. (This will also work for deselecting a larger number of samples.) To
exclude samples from the determination uncheck the check mark in front of the sample in question.
Once a sample has been determined (with or without a valid result) it is deleted from the list and the
next sample in the list becomes sample number one (the next sample to be determined). After all
samples of a list have been processed, the empty list remains on the device (it can either be refilled
with samples for the next determinations or deleted manually).
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The Sample Lists screen shows a list of all
present Sample Lists.
New Sample Lists can be created with NEW and
existing ones can be deleted, renamed or copied.
It is also possible to import sample lists that have
been set up on a personal computer from a USB
device or a network place.
User with administrator rights can also lock and
unlock sample lists.
NOTE
Locked sample lists can not be edited and the
contained samples can not be determined but
they can be used as template by copying them.
Within each sample list all contained samples are
listed together with name, type, method and weight
(except blanks, where no weight is needed).
Samples are added to the list with the NEW button.
Already existing samples can be deleted after being
selected.
With the SELECT/DESELECT ALL buttons all
samples can be selected/deselected at once.
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When adding a new sample, always a sample of
the same type like the previously added sample is
added automatically. All parameters of the newly
added sample can be adapted. Using the buttons
PREVIOUS/NEXT POSITION it is possible to
navigate from one set of sample parameters to the
parameters of the previous or following sample in
the list.
The first parameter for each sample is the sample
type:
∙ Blank,
∙ Sample,
∙ Reference substance or
∙ Control blank.
Press NEW to enter a sample of the selected type
on the next position without leaving the screen.
With OK the sample is added to the actual position
and the sample list is displayed again.
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According to the selected type of sample, a different
set of parameters is offered.
For samples of type Blank, press “Name” and enter
a name for the blank result.
Press “Method” and select the method to be used
for the determination of the blank from the list of the
available methods.
Press “Group” and select a result group for the
storage of the result from the list of the available
result groups. (It is also possible to create a new
result group using the New Group button.)
For samples of type Sample,
press “Name” and enter a name for the sample
result.
Press “Sample weight” and enter the weight of the
sample in [g] or [mL].
Press “Protein factor” and enter the protein factor
for the determination of the results.
Press “Method” and select the method to be used
for the sample determination from the list of the
available methods.
Press “Group” and select a result group for the
storage of the result from the list of the available
result groups. (It is also possible to create a new
result group using the New Group button.)
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For samples of type Reference Substance,
press “Name” and enter a name for the result of the
reference substance determination.
Press “Reference substance” and select the reference substance from the list.
Press “Sample weight” and enter the weight of the
sample in [g] or [mL].
Press “Method” and select the method to be used
for the determination of the reference substance
from the list of the available methods.
Press “Group” and select a result group for the
storage of the result from the list of the available
result groups. (It is also possible to create a new
result group using the New Group button.)
For samples of type Control Blank,
press “Name” and enter a name for the control
blank result.
Press “Method” and select the method to be used
for the determination of the control blank from the
list of the available methods.
Press “Group” and select a result group for the
storage of the result from the list of the available
result groups. (It is also possible to create a new
result group using the New Group button.)
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Using the BALANCE button the weight of samples
can be taken over from a connected balance:
∙ Select all samples using the SELECT ALL
button
∙ Press BALANCE – all blanks and control
blanks are automatically deselected (no weight
is needed for blanks)
∙ Place the first sample on the balance and
press Enter on the balance – the first weight
is taken over from the balance and entered
into the first checked sample in the list.
∙ Proceed with the next sample
∙ When all sample weights have been taken
over, the balance mode is automatically left.
NOTE
Using a bar code reader it is also possible to read
in every sample related data like name or weight
from a barcode. The read in data is automatically
filled in the active input field.
6.6.4 Sequences
The Sequences button is only available if an auto sampler is present and configured under
Device Settings Peripherals Sampler present
If the sampler has been installed and prepared properly, a sample series to be determined with a
one- or two-tray sampler can be defined and pre programmed via a sequence.
A sequence contains a number of steps defining the samples itself and the necessary system tasks
like preheating, priming, aspiration etc.
The following types of steps may be used within a sequence:
Step Explanation
Preheating The preheating procedure is performed according to the settings under
System Preparation Preheating
Priming The priming procedure is performed according to the settings under
System Preparation Priming
Rack 4 Enter the sample details for a four-place express rack. For a 2-tray sampler the tray
position (A or B) can be selected using the SETTINGS button within the step.
This step can be edited within the sequence.
Rack 12 Enter the samples for a 12 place rack. For a 2-tray sampler the tray position (A or B)
can be selected using the SETTINGS button within the step.
This step can be edited within the sequence.
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Rack 20 Enter the samples for a 20 place rack. For a 2-tray sampler the tray position (A or B)
can be selected using the SETTINGS button within the step.
This step can be edited within the sequence.
Pause The sequence is stopped until it is continued by pressing Start.
This step cannot be changed.
Cleaning The cleaning procedure is performed according to the settings under
System Preparation Cleaning
Aspiration The aspiration procedure for the sample tube and the receiving vessel is always
performed, unless the aspiration parameters of the referenced method are set to No.
(In this case the sample determination will stop after the determination of the sample
with the corresponding method.)
Dose H3BO3 This step is thought for the protection of the electrode. 50mL of boric acid are dosed
to the receiving vessel to keep the electrode immersed during non-usage of the
instrument.
This step cannot be changed.
Standby The device is sent to Standby mode.
This step cannot be changed.
NOTE
The order of the steps can not be changed once they have been added to the sequence, but steps
can always be deleted and added again in a different order. The tasks Preheating, Priming, and
Cleaning are always performed “via sampler”, if used within a sequence. Even if those tasks are set
to “unit only” within the area “System Preparation” , this setting will be omitted.
Once started, all samples within a sequence are determined automatically one by one in the workingorder of the sampler. Each sequence will be deleted from the sequence list the following day, in case
all samples have been determined properly. Sequences containing faulty samples will not be deleted.
Press the Sequences button.
Under Sequences a list of all present sample
sequences for the sampler is displayed.
New sample sequences can be created with NEW
and existing ones can be deleted, renamed or
copied.
It is also possible to import sample sequences that
have been set up on a personal computer from a
USB device or a network place.
User with administrator rights can also lock and
unlock sample sequences.
NOTE
Locked sequences can not be edited and the
determination of the sample sequence can not be
started.
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(screenshot stretched)
Press NEW to create a new sample sequence.
After entering a unique name for the new sequence
either a first single step, or a default set of the five
commonly used steps can be added to the new
sequence (press Add Defaults to add the default
set of steps or select a single step from the list and
press OK).
Additional steps can be entered by pressing NEW.
NOTE
Since the order of the steps can not be changed
afterwards, make sure to add the steps in a reasonable order.
To change the order of steps within a sequence
you have to delete selected steps and to add them
again in a reasonable order.
NOTE
Except the steps “Rack 4“, “Rack 12“, and “Rack
20“ none of the steps can be changed from within
the sequence. (See the table at the beginning of
this chapter for details.)
The tasks Preheating, Priming, and Cleaning are
always performed “via sampler”, if used within a
sequence. Even if those tasks are set to “unit only”
within the “System Preparation” under “Preparative
tasks”, this setting will be omitted.
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Click on the Rack step to adapt the settings of the
rack and to add samples to the rack.
Press SETTINGS and adapt the settings for the
rack:
“Determine blanks first” Yes/No
(If blanks are determined first, the risk of a crosscontamination can be minimized for the blanks.)
“Pause after blank calculation” Yes/No
A pause after the blank calculation leaves a user
with operator rights the chance to eliminate a faulty
blank determination from the calculation before
any sample determinations are corrected with the
calculated blank.
The third setting is only available for 2-tray samplers:
“Use tray in sampler” A/B
Define the position of the rack in the K-377 sampler.
The step will be marked with A or B.
The positions of the rack can be filled one by one
with samples by clicking on each position.
NOTE
Using the buttons PREVIOUS POSITION and
NEXT POSITION you can switch easily from one
sample to the next/previous within each parameter
screen. Thus each parameter can be adapted for all
samples of the rack in a very easy and convenient
way.
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The first parameter for each sample is the sample
type:
∙ Blank,
∙ Sample,
∙ Reference substance or
∙ Control blank.
Press NEW to enter a sample of the selected type
on the next position without leaving the screen.
With OK the sample is added to the actual position
and the sample list is displayed again.
(According to the selected type of sample, a
different set of parameters is offered.)
For samples of type Blank,
press “Name” and enter a name for the blank result.
Press “Method” and select the method to be used
for the determination of the blank from the list of the
available methods.
Press “Group” and select a result group for the
storage of the result from the list of the available
result groups. (It is also possible to create a new
result group using the New Group button.)
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For samples of type Sample,
press “Name” and enter a name for the sample
result.
Press “Sample weight” and enter the weight of the
sample in [g] or [mL].
Press “Protein factor” and enter the protein factor
for the determination of the results.
NOTE
Using a bar code reader it is also possible to read
in every sample related data like name or weight
from a barcode. The read in data is automatically
filled in the active input field.
Press “Method” and select the method to be used
for the sample determination from the list of the
available methods.
Press “Group” and select a result group for the
storage of the result from the list of the available
result groups. (It is also possible to create a new
result group using the New Group button.)
For samples of type Reference Substance,
press “Name” and enter a name for the result of the
reference substance determination.
Press “Reference substance” and select the reference substance from the list.
Press “Sample weight” and enter the weight of the
sample in [g] or [mL].
Press “Method” and select the method to be used
for the determination of the reference substance
from the list of the available methods.
Press “Group” and select a result group for the
storage of the result from the list of the available
result groups. (It is also possible to create a new
result group using the New Group button.)
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For samples of type Control Blank,
press “Name” and enter a name for the control
blank result.
Press “Method” and select the method to be used
for the determination of the control blank from the
list of the available methods.
Press “Group” and select a result group for the
storage of the result from the list of the available
result groups. (It is also possible to create a new
result group using the New Group button.)
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Using the BALANCE button the weight of samples
can be taken over from a connected balance:
∙ Select all samples
∙ Press BALANCE – all blanks and control
blanks are automatically deselected (no weight
is needed for blanks)
∙ Place the first sample on the balance and
press Enter on the balance – the first weight
is taken over from the balance and entered
into the first checked sample in the list.
∙ Proceed with the next sample
∙ When all sample weights have been taken
over, the balance mode is automatically left.
If certain samples of a rack that is already in progress have to be determined immediately this can be
done using the Split Rack functionality:
Press PAUSE to stop the determination of the
sequence.
Select the samples to be determined immediately
and press SPLIT RACK.
The selected samples will be deleted from the
sequence and will be inserted into the rack-step of
a new created sequence at the same position of the
rack.
The newly created Split-Sequence can be started
to determine express samples – afterwards the
previous sequence can be continued.
NOTE
Using the button EDIT MODE it is possible to edit
samples of a rack that is not yet being processed
during a running sequence.
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6.7 Results
In the result area all tasks related to the results (viewing, printing, and exporting) can be performed.
6.7.1 Result groups
As the name implies, result groups are folders in which results can be stored and grouped in accordance with their properties.
The group a result shall be assigned to can be specified using the corresponding sample parameter
“Group” while defining single samples, sample lists or sequences.
The Result Groups screen shows a list of all
present groups, available for the storage of
results.
Result groups can be created, renamed and deleted by users with administrator rights. User with
operator rights are only allowed to create new result groups. Using the F I LT E R button, the list of the
Result groups can be filtered with respect to the name and the creation date of the group:
Set the “Group filter” to On to filter the list of
result groups. Select Yes for “Filter between
dates” if you wish to filter the list with respect to
the creation or rename date and specify a time
period using begin and end date.
Specify a part of the group name as filtering criterion using “Group name contains”.
NOTE
All specified filters are correlated using the logical
”AND” – meaning every condition specified in
the filter settings must apply in order for a group
to match the filter.
Once a filter has been set, the FILTER button is switched to FILTER ACTIVE:
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The content of selected groups or selected results can be printed (PRINT) or exported (EXPORT) to
a memory stick or network folder. The path to the network folder and to the target directory on the
memory stick can be defined under Settings Import & Export (see chapter “6.9.1 Settings“).
Just like the list of the result groups, also the list of the contained results can be filtered. Enter a sample
group to set the sample filter:
Press FILTER to set the sample filter.
Set the “Sample filter” to On to filter the list of
displayed results. Select Yes for “Filter between
dates” if you wish to filter the list with respect to the
creation date and specify a time period using begin
and end date.
The list of displayed results can be restricted to one
or more certain types of results (blanks, samples,
references, control blanks).
NOTE
All specified filters are correlated using the logical
”AND” – meaning every condition specified in the
filter settings must apply in order for a group to
match the filter.
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6.7.2 Last Results
The Last Results screen shows a list of the last 40 results of the system, regardless to the type of
the results.
The sample report of selected results can be printed
either detailed or short. Results can be exported to
a USB stick or a network place.
NOTE
The last results are shown regardless of the result
group they are assigned to.
Clicking on a single result opens the detailed sample report:
With PREVIOUS SAMPLE and NEXT SAMPLE
you can navigate back and forth within the sample
reports of the stored samples.
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6.7.3 Blank Correction
The blank correction can be switched on and off:
HOME Blank Correction SETTINGS
ON Blank correction of results is switched on.
OFF Blank correction of results is switched off –
no blank correction at all will be performed.
Within the Blank Correction main screen a list of the latest blanks can be viewed. By adapting the
parameter “Blanks in list” under SETTINGS it can be determined how many blanks will be shown in
this list:
- Will decrease the number of displayed blanks
by 10.
+ Will increase the number of displayed blanks
by 10.
A maximum number of 90 blanks can be listed.
In general four different possibilities for the determination of the active blank value for the automatic
correction of results are available:
∙ Blank values can be measured (type: measured).
∙ Blank values can be entered manually (type: manual).
∙ Blank values can be calculated as mean value of freely selectable measured blanks (type:
mean).
∙ Blank values can be determined automatically by the system (type: automatic).
The type and the value of the blank currently used for result correction is always displayed in the
results section of the status view:
SHOW S TAT U S RESULTS (See section 6.5.1)
Entering Manual blanks
To enter a blank value manually (e.g. for a blank value that has not been determined with the instrument), proceed as follows:
Enter the Blank Correction screen.
Press SETTINGS.
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Within the settings for the blank correction,
∙ switch “Blank correction” ON
∙ switch “Auto blank generation” OFF
∙ select NO for “Use last measured blank”
∙ confirm your settings with OK.
Press MANUAL
Enter a name for the manual blank value.
Enter the volume for the blank in [mL]
Confirm your settings with OK.
The entered blank value is now automatically selected and shown in the list of blanks in the Blank
Correction screen.
Manually entered blanks are listed in the blank list with type “manual”.
NOTE
If you select Yes for “Use last measured blank“ the next measured value for a sample of Type “Blank“
will be used for the correction of all subsequent sample determinations. All sample determinations up
to the next blank determination will still be corrected using the currently selected blank value.
Defining Mean blanks
Mean blank values can be calculated over two or more measured blank values. To define a Mean
blank value, proceed as follows:
Enter the Blank Correction screen.
Press SETTINGS.
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Within the settings for the blank correction,
∙ switch “Blank correction” ON
∙ switch “Auto blank generation” OFF
∙ select NO for “Use last measured blank”
∙ confirm your settings with OK.
Press MEAN
Enter a name for the mean blank value.
Check the check box of those measured blank
values that shall be used for the calculation of the
mean value.
Confirm your selection with OK.
The calculated mean blank value is now automatically selected and shown in the list of blanks in the
Blank Correction screen.
Averaged blanks are listed in the blank list with type “mean”.
NOTE
If you select Yes for “Use last measured blank“ the next measured blank value will be used for the
correction of all subsequent sample determinations. All sample determinations up to the next blank
determination will still be corrected using the currently selected blank value.
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Automatic Blank determination
With automatic blank determination switched on, each continuous row of measured blanks is automatically averaged and the resulting mean value is used for the correction of the subsequently
measured sample(s). After one or more samples have been determined, the next measured blank (or
the mean of the next measured continuous row of blanks) will be used as active blank value for the
correction of the subsequent samples until the next blank is determined.
Automatically determined blanks are listed in the blank list with type “automatic”.
Enter the Blank Correction screen.
Press SETTINGS.
Within the settings for the blank correction,
∙ switch “Blank correction” ON
∙ switch “Auto blank generation” ON
∙ optionally select YES for “Monitor blank limits”
Set the tolerable range for each blank, compared
with the mean blank value by defining the Upper
and Lower blank limit
∙ confirm your settings with OK.
The currently active blank can be viewed in the RESULT display of the status view.
NOTE
If you select Yes for “Use last measured blank“ the next measured blank value will be used for the
correction of all subsequent sample determinations. All sample determinations up to the next blank
determination will still be corrected using the currently selected blank value.
Monitoring the blank limits
If the function “Monitor blank limits” is switched on, a tolerable range (defined by the upper- and lower
limit in percent) can be defined for an automatically calculated blank value. Each new determined
blank that would be part of this calculation, is compared to the already calculated mean value. If the
deviation of this blank value is outside of the specified range, the sequence is stopped and a warning
message is displayed.
Changing an automatically calculated blank after it was used for sample correction
A user with operator rights is not allowed to change any calculated mean blank value that has already
been used for the correction of any results. Since this proceeding would have an impact to the calculated results this option is restricted to users with administrator rights. Each blank that was changed
subsequently (after it was used for sample correction) is marked with a “*”.
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6.8 Determination Parameters
Within this area, the methods for determinations with the K-375 can be written and the resources like
reference substances or volumetric solutions for the titration can be defined and edited.
(Once defined, the resources can be referenced from within the method.)
6.8.1 Methods
The structure of the K-375 method is highly flexible and offers all possibilities to create a method that
reflects the special needs of the user.
Each method consists of 4 different parameter sets:
∙ Parameters for the sample distillation
∙ Parameters for the sample titration
∙ Parameters for the sample determination (calculating the result)
∙ Parameters for the aspiration
NOTE
The method does not cover system preparation tasks like Preheating, Priming, and Cleaning – for
single samples or sample lists those tasks have to be performed manually previous to a sample
determination (See chapter “6.6.1 System Preparation“). For sequences (automated determination of sample racks with a sampler) the system preparation tasks can be defined within the Sample
Sequence previous to or after the determination of a complete rack (see chapter “6.6.4 Sequences“).
Within the Methods screen, methods can be
created, deleted, renamed, copied or printed.
A new method is created using the NEW button.
The name for a new method has to be unique.
With the buttons IMPORT and EXPORT, accessible via the SHOW OPTIONS button, methods
can be imported from, or exported to a memory
stick or a network folder.
The path to the network folder and to the target
directory on the memory stick is defined under
Settings Import & Export (see chapter “6.9.1
Settings“).
NOTE
Methods marked with a small padlock are predefined and can neither be deleted nor changed.
Nevertheless they can be copied and stored as a
new method which can be changed.
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The different areas of the method are separated
from each other by the corresponding heading. The
Method Information section at the bottom of each
method provides information about the last modification date and the creator of the method.
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