Milwaukee MI455 User manual

INSTRUCTION MANUAL
SATISFACTION
GUARANTEED
MI455
Minititrator for Wine Analysis
Free&Total Sulphur Dioxide

All rights are reserved. Reproduction in whole or in part is prohibited without the written
consent of the copyright owner, Milwaukee Instruments Inc., Rocky Mount, NC 27804 USA.
THANK YOU for choosing Milwaukee Instruments!
This instruction manual will provide you the necessary information for correct use
of the meter.

3
TABLE OF CONTENTS
1. FUNCTIONAL DESCRIPTION......................................................................................................................................4
2. GENERAL DESCRIPTION.............................................................................................................................................6
3. PRINCIPLE OF OPERATION........................................................................................................................................8
4. SPECIFICATIONS.............................................................................................................................................................8
5. STARTUP .............................................................................................................................................................................9
6. GUIDE TO DISPLAY CODES......................................................................................................................................10
7. GENERAL TIPS FOR AN ACCURATE MEASUREMENT.................................................................................12
8. PUMP CALIBRATION PROCEDURE......................................................................................................................13
9. FREE SO₂ MEASUREMENT PROCEDURE .........................................................................................................15
10. TOTAL SO₂ MEASUREMENT PROCEDURE ..................................................................................................... 17
11. PUMP TUBE REPLACEMENT..................................................................................................................................19
12. FUSE REPLACEMENT...............................................................................................................................................20
13. ELECTRODE CONDITIONING & MAINTENANCE..........................................................................................21
14. ACCESSORIES..............................................................................................................................................................23
CERTIFICATION..................................................................................................................................................................24
RECOMMENDATION........................................................................................................................................................24
WARRANTY..........................................................................................................................................................................25

4MI455 Minititrator for Wine Analysis
1. FUNCTIONAL DESCRIPTION
Display
A. HOURGLASS ICON
B. STIRRER ACTIVE TAGS
C. ERROR MESSAGE
D. MEASURE STATUS
E. CALIBRATION MODE INDICATOR
F. MAIN DISPLAY
G. MEASUREMENT UNIT
H. TIMER MODE INDICATOR
I. SECONDARY DISPLAY
Keypad
MI455 Sulphur Dioxide
Mini Titrator
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

FUNCTIONAL DESCRIPTION 5
Front Panel
A. TITRANT BOTTLE
B. LIQUID CRYSTAL DISPLAY (LCD)
C. KEYPAD
D. ELECTRODE HOLDER
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

6MI455 Minititrator for Wine Analysis
2. 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 eective 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 eective 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 SO₂ suppresses the activity of enzymes that cause browning and
other 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 SO₂ addition becomes bounded. What remains is
called “free” and it is divided in two parts. The larger, and relatively ineective free part is
“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 SO₂ concentration (ppm) for 0.8 ppm molecular SO₂:
pH 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9
Free SO₂ 14 18 22 28 35 44 55 69 87 109

GENERAL DESCRIPTION 7
In most situations, 0.8 ppm molecular SO₂ during bulk storage and at bottling will
provide you with adequate protection from oxidation and bacterial action. This includes
prevention 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 SO₂ can be detected by the human senses is about 2.0ppm.
This is also the level which is needed for maximum protection of your wine. This is
particularly true in the case of sweet, and most notably, botrytised wines.
The Milwaukee MI455 oers the possibility to test free or total SO₂ in all the wines
including the red ones, that are diicult to test with manual methods because the color
changes are hardly seen.
This meter is supplied with:
yReagent set for SO₂ determinations
yTwo 100 mL beakers
yTwo 20 mL beakers
yTubes set with cap
yORP probe
yStir bar
yPower cable
yOne 230 mL bottle of Refill Solution
yOne plastic pipette
yInstruction manual
yWarranty 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.

8MI455 Minititrator for Wine Analysis
3. 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 dierential 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.
4. SPECIFICATIONS
Range 0 to 400 ppm SO₂
Resolution 1 ppm
Accuracy 5% of reading
Method Ripper titrimetric method
Principle Equivalence point redox titration
Sample volume 50 mL
ORP Electrode MA924B/1 (included)
Pump debit 0.5 mL/min
Stirring speed 700 rpm
Environment 0 to 50 °C (32 to 122 °F) ; max 95% RH non-condensing
Power supply MI455-01: 115 V/60 Hz; 10 VA
MI455-02: 230 V/50 Hz; 10 VA
Dimensions 208 x 214 x 163 mm (8.2 x 8.4 x 6.4”) (with beaker)
Weight 2200 g (77,6 oz.).

STARTUP 9
Required Reagents
Code Description Quantity/test
Mi555-001 Standard (for Free & Total SO₂) 50 mL
Mi555-002 Titrant (for Free & Total SO₂)
Mi555-003 Alkaline Reagent (for Total SO₂) 5 mL
Mi555-004 Acid Reagent (for Total SO₂) 5 mL
Mi555-005 Acid Reagent (for Free SO₂) 5 mL
Mi555-006 Stabilizer (for Free & Total SO₂) 1 packet
5. STARTUP
yPlace the instrument on a flat table. Do not place the instrument on direct sun light.
yConnect the titrator to mains socket with ground connection and the correct voltage
and frequency. See the label on the instrument rear for this.
yPlace the peristaltic pump tube on the pump. See the Pump Tube Replacement
section for the procedure.
yRemove the reagent bottle cap and place the bottle cap of the tubes set. Place the
reagent bottle in the appropriate place on the titrator top.
yConnect the tubes with the peristaltic pump (inlet tube is connected with the reagent
bottle, outlet tube is connected with the dosing tip).
yTurn the instrument ON using the power switch from the rear panel of the instrument
and wait until it displays dashes.

10 MI455 Minititrator for Wine Analysis
6. GUIDE TO DISPLAY CODES
This screen appears for a few seconds each time the
instrument is turned ON.
Main screen display.
Main screen display with stirrer active.
Purging mode message.
Pump Calibration Messages
This screen appears each time the meter enters pump
calibration mode. The meter is ready to start pump
calibration by pressing the START STOP button.
This screen appears while pump calibration is in progress.
Pressing CAL or START STOP button, the minititrator
returns to the main screen.
This screen appears for a few seconds before returning to
the main screen, when pump calibration is done.