biochrom Libra S4 User Manual

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Libra S4

User Manual

Declaration of Conformity

This is to certify that the Libra S4 Visible Spectrophotometer
Part number 80-5000-00
Serial number 88000 onwards

manufactured by Biochrom Ltd. conform to the requirements of the following
Directives-: 73/23/EEC & 89/336/EEC

Standards to which conformity is declared

EN 61 010-1: 2001
Safety requirements for electrical equipment for measurement, control and

laboratory use.

EN 61326: 1998
Electrical equipment for measurement, control and laboratory use – EMC

requirements

Signed: Dated: 26

th

Oct 2004

David Parr
Managi ng Direc tor
Biochrom Ltd

Postal address Telephone Telefax
Biochrom Ltd [phone] [phone]

22 Cambridge Science Park
Milton Road e mail: enquiries@bio chr om.co.uk website: http://www.biochrom.co.uk
Cambridge CB4 0FJ
England

Registered in England No: 3526954
Registered Office: 22 Cambridge Science Park, Milton Road, Cambridge CB4 0FJ, England

.

Biochrom Ltd

Certificate No. 890333

CONTENTS

Unpacking, Positioning and Installation 1
Essential Safety Notes 1

OPERATION 2

Introduction 2
Sample handling tips 2
Using the Instrument 3
Absorbance and % Transmission 4
Concentration 4
Rate 6
Factor 7

(time and date) 8
Use with serial printer 8
Use with chart recorder 8

USE WITH PC AND THE GRAFICO PC UTILITY
SOFTWARE 9

Installation 9
Introduction 9
Menu Descriptions 10
Practical Aspects 11

ACCESSORIES 12
ERROR MESSAGES 12
MAINTENANCE 13

After Sales Support 13
Cleaning and gen eral care of th e instru men t 13
Changing cell holder or removal for cleaning 13
Lamp Replacement 14
Changing the brightness of the display 14

STUDENT EXPERIMENTS 15

Calculation of λ max, extinction coefficient and measurement of natural
bandwidth 16
Construction of concentration plots 16
Measurement of stray light 17

SPECIFICATION AND WARRANTY 18

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Issue 02 - 03/2005 Libra S4, English 1

Unpacking, Positioning and Installation

• Inspect the instru ment for any signs of damage caused in tran si t. If any damage is

discovered, inform your supp lier immediately. Check the position of the metal lamp
bracket insid e the lamp access area.

• Ensure your proposed installation site conforms to the environmental conditions for safe

operation:

Indoor use only
Temperature 5°C to 35 °C. No te that if you use the instr ument in a room sub j ect t o
extremes of temperature change du r ing the day, it may be necessary to recalibrate (b y
switching off and then on again) once thermal equilibrium has been established (2-3
hours).
Maximum relative humidity of 80 % up to 31°C decreasing linearly to 50 % at 40°C

• The instrument must be placed on a hard, flat bench or table that can take its weight (<2

kg) such that air is allowed to circulate freely around the inst rument.

• This equipment must be connected to the power supply with the power cord supplied. It

can be used on 90 - 240V supplies.

• Switch on the instrument via the display after it has been plugged in. The instrument

performs a series of self-diagnostic checks for lamp performanc e, wavelength calibration
and diode array pixels; press F2 to proceed.

If the instrument has just been unpacked or has been stored in a cold environment, it
should be allowed to come to thermal equilibrium for 2-3 hours in the laboratory
before switching on to prevent calibratio n failure as a re sult of internal co nd ensation.

• The cell holder supplied with the instrument accepts standard 10mm pathlength glass or

plastic cells (adap t er s are avai lable to convert it to accept 10, 12 and 16mm diameter test
tubes). It can be removed for cleaning if spillages occur by undoing the screws that hold
it or it can be flushed through with water in situ.

If this equipment is used in a manner not specified or in environmental conditions not
appropriate for safe operation, the protection provided by the equipment may be impaired and
instrument w a rranty withdrawn.

Essential Safety Notes

There are a number of warning labels and symbols on your instrument. These are
there to inform you where potential danger exists or particular caution is required.
Before commencing installation, please take time to familiarise yourself with these
symbols and their meaning.

Caution (refer to accompanying documents).
Background colour yellow, symbol and outline black.

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Issue 02 - 03/2005 Libra S4 , English 2

OPERATION

Introduction

Your spectrophotometer is a simple-to-use instrument that provides rapid
measurement of light absorbance and light transmission in the visible region (330 –
800 nm).

Your spectrophotometer has facilities for measurement of:

• absorbance and % transmission

• concentration, either

• absorbance multiplied by a factor or

• from a single point calibration using a known standard

• rate (absorbance against time) at one or two wavelengths simultaneously

• rate results at one wavelength can be output to chart recorder

The instrument is supplied with Grafico PC utility - on the accompanying CD - and a
serial lead. These provide the user with the means to capture, print and store data
from the instrument to a PC. Specifically it

• produces a printable graphical plot of the scan, in Abs

• logs date, time and serial number with any output from the instrument

• produces a results log in order to store, tabulate and subsequently print

output from the instrument

• enables export of the output from the instrument to Excel as a text file

A tutorial on UV/Visible spectrophotometry is included as part of the Grafico
software.

Experiments are included in this manual for the user or for students to investigate
some of the principles of UV/Visible spectrophotometry.

Sample handling tips

• Note that the light beam shines from LEFT to RIGHT through the cell chamber;

ensure the cell is inserted in the correct alignme nt.

• The optical height is 15mm, and the minimum volume that can be used is
approx. 700µl in a semi-micro cell.

• Align the indicator line on test tubes with the arrow on the cell compartment
area to ensure reproducible positioning of the tube. Note that test tubes do not
last forever, and that the surface gets scratches and blemishes through repetitive
use; if this is the case they should be replaced.

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Issue 02 - 03/2005 Libra S4, English 3

Using the Instrument

The liquid crystal display is very easy to navigate around using the function / select
and arrow keys on the hard wearing, spill proof membrane keypad.

Keypad

To switch the ins tr u men t o n, press once
To switch the instrument off, hold the key down for 2 seconds

√

To set up or confirm an entry

0A/100%T To set reference to 0.000AU or 100%T on a reference solution at the

selected wavelength
To make a measurement or stop a rate experiment

34

To highlight the 6 measurement indicat ors in turn ( see below)

56

Depends on mode, see below

Display

Highlight your selection using 34, then:

nm

To enter wavelength; to select, press 56 then √

Abs/%T

To measure Abs or %T; to select , p r es s 56 (“Abs” or “%T”
displayed at side)

Conc To measure concentration either using a factor or relat ive to a known

standard; to select, press √ (“Conc.” displayed at side)
Rate To measure absorb an ce as a fun c tion of time; to select, p r es s √
Factor To enter a factor for use in concentration; to select, press √

To display time and change time / date if required ; to select , p r ess √
The following symbols appear and signify the following:

r r r r

Setting reference / measuring blan k
“0.123” flashing

Displaying previo usly measured value when measuring sample

Error Messages

Error messages may appear on the display and mean the following:

FAIL flashing Can carry on using; refer to error messages section
FAIL constant Cannot use; refer to error messages section and contact your supplier