Milwaukee Instruments Mi455 User Manual
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INSTRUCTION MANUAL
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Instruction Manual Mi455 FREE & TOTAL SULPHUR DIOXIDE Minititrator for wine analysis
TABLE OF CONTENTS
FUNCTIONAL DESCRIPTION ............................................................................... 3
GENERAL DESCRIPTION ..................................................................................... 4
PRINCIPLE OF OPERATION .................................................................................. 6
SPECIFICATIONS ............................................................................................... 7
STARTUP ........................................................................................................... 8
GUIDE TO DISPLAY CODES ................................................................................. 9
GENERAL TIPS FOR AN ACCURATE MEASUREMENT ............................................... 11
PUMP CALIBRATION PROCEDURE ...................................................................... 11
FREE SO
TOTAL SO
PUMP TUBE REPLACEMENT ................................................................................ 15
FUSE REPLACEMENT ......................................................................................... 16
ELECTRODE CONDITIONING AND MAINTENANCE ............................................. 16
ACCESSORIES ................................................................................................. 18
MEASUREMENT PROCEDURE ............................................................... 13
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MEASUREMENT PROCEDURE ............................................................. 14
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FUNCTIONAL DESCRIPTION
DISPLAY
A. HOURGLASS ICON
B. BATTERY STATUS ICON
C. ERROR MESSAGE
D. MEASURE STATUS
E. CALIBRATION MODE INDICATOR
F. MAIN DISPLAY
G. MEASUREMENT UNIT
H. TIMER MODE INDICATOR
I. SECONDARY DISPLAY
FRONT PANEL
A. TITRANT BOTTLE
B. LIQUID CRYSTAL DISPLAY (LCD)
C. KEYPAD
D. ELECTRODE HOLDER
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REAR PANEL
E. ORP ELECTRODE
F. PERISTALTIC PUMP TUBE
G. BEAKER
H. PERISTALTIC PUMP
I. BNC ELECTRODE CONNECTOR
J. FUSE
K. POWER CABLE CONNECTOR
L. POWER SWITCH
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Instruction Manual Mi455 FREE & TOTAL SULPHUR DIOXIDE Minititrator for wine analysis
KEYPAD
A. PUMP - to start/stop the pump
B. CAL - to enter pump calibration mode
C. STIR - to start/stop the stirrer while in
measurement or purging mode
D. START STOP - to start/stop titration or
pump calibration
GENERAL DESCRIPTION
The Mi455 is a low-cost, easy to use, microprocessor-based automatic titrator. It has a
simple and reliable peristaltic pump that ensure high dosing repeatability. By performing
pump calibration with the provided Milwaukee standards, the instrument accuracy is assured.
The instrument comes with a pre-programmed analysis method designed for Free and
Total Sulphur Dioxide measurements on wine samples. The instrument has a powerful
and effective built-in algorithm to analyze the shape of the electrode response and to
determine the reaction completion. This algorithm automatizes the analysis, makes all
the necessary calculations and assures a simple and effective interface for the user.
By simply pressing the START STOP button, the instrument will automatically make the
titration up to the equivalence point. The result is immediately displayed in convenient
units, then the instrument is ready for another titration.
SIGNIFICANCE OF USE
An important reason for adding SO2 is to avoid oxidation. When there is oxygen around,
SO2 itself becomes oxidized before phenol compounds in the wine , and so acts as an oxygen
scavenger. Also SO
problems.
What is really protecting your wine is molecular SO2. When you add SO2, depending of
circumstances, some of it immediately becomes bound. The relationship between the
amount of added SO2 and the amount of SO2 remaining free is complex. It is clear,
however, that it is largely governed by the total SO2 content of the wine. The rate of binding
decreases as the free SO2 concentration increases. The exact relationship between free
and bound (total - free) SO2 will vary from wine to wine.
Below 30-60 ppm, 33% to 50% of SO
called “free” and it is divided in two parts. The larger, and relatively ineffective free part is
suppresses the activity of enzymes that cause browning and other
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addition becomes bounded. What remains is
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“bisulphite” (HSO3-). The smaller part of the free is the active molecular SO2. The amount
of molecular SO2 in your wine depends both on the level of free SO2 present as well as pH.
For instance, at pH 3.2, the amount of free SO2 for 0.8 ppm molecular SO2 is 22 ppm. At
pH 3.5, you will need 43 ppm free - essentially double.
Free SO
concentration (ppm) for 0.8 ppm molecular SO2:
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In most situations, 0.8 ppm molecular SO
you with adequate protection from oxidation and bacterial action. This includes prevention
during bulk storage and at bottling will provide
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of malolactic bacteria as well.
It is important to remember that the amount of free SO2 in the wine depends on three
things: how much is added, how much was present before the addition and how much of
your addition promptly becomes bound.
The level at which molecular SO
This is also the level which is needed for maximum protection of your wine. This is
can be detected by the human senses is about 2.0 ppm.
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particularly true in the case of sweet, and most notably, botrytised wines.
The Milwaukee Mi455 offers the possibility to test free or total SO
including the red ones, that are difficult to test with manual methods because the color
in all the wines
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changes are hardly seen.
This meter is supplied with:
• Reagents set for 20 titrations
• Two 50 mL beakers
• Two 20 mL beakers
• Tubes set with cap
• ORP probe
• Stir bar
• Power cable
• One 230 mL bottle of Refill Solution
• One 1 mL syringe
• Instruction manual
• Warranty code
Note: Save all packing material until you are sure that the instrument works correctly.
Any defective item must be returned in its original packing.
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Instruction Manual Mi455 FREE & TOTAL SULPHUR DIOXIDE Minititrator for wine analysis
PRINCIPLE OF OPERATION
Determination of sulphur dioxide in wine samples is made by titration of the sulphur
dioxide present in wine with iodate. In this procedure an excess of iodine is added to the
wine sample and it is titrated with iodate.
For precise results it is very important to know the exact sample volume, titrant volume and
concentration.
The peristaltic pump has a good repeatability but the dosing volume depends on many
factors as the diameter of the tube or the tube stretching. To compensate for all this errors,
the pump need to be calibrated. The calibration of the pump is also needed in order to have
high precision of the titrations.
The calibration procedure is in fact the analysis of a known solution. By doing this, the
instrument makes a differential analysis between the standard and the wine sample. The
pump volumetric debit and the real concentration of the titrant is compensated. Only the
sample volume has to be precisely known.
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