Milwaukee MI456 User manual
INSTRUCTION MANUAL
SATISFACTION
GUARANTEED
MI456
Minititrator for Wine Analysis
Titratable Total Acidity
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.............................................................................................................................................................9
5. STARTUP ...........................................................................................................................................................................10
6. GUIDE TO DISPLAY CODES......................................................................................................................................10
7. GENERAL TIPS FOR AN ACCURATE MEASUREMENT.................................................................................13
8. PUMP CALIBRATION PROCEDURE......................................................................................................................14
9. pH CALIBRATION PROCEDURE.............................................................................................................................15
10. MEASUREMENT PROCEDURE .............................................................................................................................16
11. PUMP TUBE REPLACEMENT.................................................................................................................................. 17
12. FUSE REPLACEMENT................................................................................................................................................18
13. ELECTRODE CONDITIONING & MAITENANCE.............................................................................................19
14. ACCESSORIES...............................................................................................................................................................21
CERTIFICATION..................................................................................................................................................................22
RECOMMENDATION........................................................................................................................................................22
WARRANTY..........................................................................................................................................................................22
4MI456 Minititrator for Wine Analysis
1. FUNCTIONAL DESCRIPTION
Display
A. STABILITY INDICATOR: when reading is unstable or calibration is in progress
B. STIRRER ACTIVE TAGS
C. CALIBRATION MESSAGES
D. PUMP ACTIVE TAGS
E. CALIBRATION MESSAGES
F. “pH” TAG: when a buer is displayed on the secondary display
G. FOUR DIGITS AND HALF SECONDARY DISPLAY
H. “Time” TAG: when the time is displayed on the secondary display
I. FOUR DIGITS AND HALF MAIN DISPLAY
J. “pH” UPPER TAG: when the end point is modified
K. AUTOMATIC TEMPERATURE COMPENSATION: when ATC blinks the temperature probe is
not connected and the temperature is considered to be 25 °C
L. CALIBRATION MODE INDICATOR
Keypad
MI456 Titratable Total Acidity
Mini Titrator
A. PUMP - to start/stop the pump
B. CAL - to enter pump or pH calibration mode
C. pH - to enter pH calibration mode (CAL tag is active) to modify the end point value
D. STIR - to start/stop the stirrer while in measurement or purging mode
E. START STOP - to start/stop titration
FUNCTIONAL DESCRIPTION 5
Front Panel
A. TITRANT BOTTLE
B. LIQUID CRYSTAL DISPLAY (LCD)
C. KEYPAD
D. ELECTRODE HOLDER
Rear Panel
E. pH ELECTRODE
F. TEMPERATURE PROBE
G. PERISTALTIC PUMP TUBE
H. BEAKER
I. PERISTALTIC PUMP
J. TEMPERATURE PROBE CONNECTOR
K. BNC ELECTRODE CONNECTOR
L. FUSE
M. POWER CABLE CONNECTOR
N. POWER SWITCH
6MI456 Minititrator for Wine Analysis
2. GENERAL DESCRIPTION
The MI456 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 preprogrammed analysis method designed for
Total Titratable Acidity measurements on wine.
The MI456 performs automatic analysis, all the necessary calculations and assures to
the user a simple and eective interface.
The instrument has a powerful and eective built-in algorithm to analyze the shape of the
pH electrode response and to determine the reaction completion.
By simply pressing the START STOP button, the instrument will automatically make the
titration up to the end point. The result is immediately displayed in convenient units, then
the instrument is ready for another titration.
Significance of Use
Acids occur naturally during the growing of grapes and as part of the fermentation
process. Wines show lower levels of acid when there are hot growing seasons or when
the grapes come from hotter regions. In the proper proportion, acids are a desirable trait
and give the wine character.
The three predominant acids in wine are tartaric, malic and citric, all of which are
intrinsic to the grape. Tartaric acid is the principal acid in grapes and is a component
that promotes a crisp flavor and graceful aging in wine. A moderate amount of a wine’s
acid comes from malic acid, which contributes to fruitiness, and a small amount comes
from citric acid. Wine also contains trace amounts of other acids. The least desirable
acid in wine is acetic acid, which, when present in more than a nominal amount, gives
wine a sour or vinegary aspect.
Total acidity, also called titratable acidity, is the sum of the fixed and volatile acids. In the
United States the total acidity is usually expressed in terms of tartaric acid, even though
the other acids are measured.
Total Acidity directly eects the color and flavor of wine and, depending on the style of
the wine, is sought in a perfect balance with the sweet and bitter sensations of other
components. Too much acidity makes wine tart and sharp; too little makes wines flat,
flabby and uninteresting.
GENERAL DESCRIPTION 7
Proper acidity in wine is what makes it refreshing and an ideal accompaniment to food.
The proper acid level of a wine varies, with sweeter wines generally requiring somewhat
higher levels to retain the proper balance. For dry table wine the acceptable range is
usually 0.60 to 0.75%; for sweet wine it’s 0.70 to 0.85%.
This meter is supplied with:
yReagent set for titratable total acidity in wine
yOne 2000 µL automatic pipette
yTwo plastic tips for the 2000 µL automatic pipette
yTwo 100 mL beakers
yTubes set with cap
ypH electrode
yTemperature 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.
8MI456 Minititrator for Wine Analysis
3. PRINCIPLE OF OPERATION
The determination of total acids in wine is made according to a neutralization reaction,
that is the reaction between the acids found in wine and a base. This type of reaction
forms the basis of titration methods of analysing acids.
Titratable acidity is measured on a degassed sample at the end-point of 8.20 for Australian
requirements and 7.00 to fulfil the requirements of the European Union. Both results are
expressed as g/L tartaric acid.
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 streching. 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. It is important to calibrate the pump at the pH value
you want to use as the endpoint of the titrations.
The calibration procedure is in fact the analysis of a known solution. By doing this, the
instrument makes a dierential 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.
SPECIFICATIONS 9
4. SPECIFICATIONS
Range 0.0 to 25.0 g/L of tartaric acid
Resolution 0.1 g/L
Accuracy 5% of reading
Method Acid-base titration method
Principle End-point titration
pH Calibration One-point in selected end-point: 7.00 pH or 8.20 pH
Sample volume 2 mL
Temperature Compensation Automatic from 0.0 to 100.0 °C
pH Electrode MA919B/1 (included)
Temperature Probe MA831R (included)
Pump debit 0.5 mL/min
Stirring speed 1500 rpm
Environment 0 to 50 °C (32 to 122 °F) ; max 95% RH non-condensing
Power supply MI456-01: 115 V/60 Hz; 10 VA
MI456-02: 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.)
Required Reagents
Code Description Quantity/test
Mi556-001 Standard 2 mL 2 mL
Mi556-002 Titrant
Mi556-003 Buer pH 7.00 50 mL 50 mL
Mi556-004 Buer pH 8.20 50 mL
10 MI456 Minititrator for Wine Analysis
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.
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.
GUIDE TO DISPLAY CODES 11
Pump Calibration Messages
This screen appears each time the meter enters pump or pH
calibration mode by pressing the CAL button. The meter is ready
to start pump calibration by pressing the PUMP button. The
meter returns to the main screen by pressing the CAL 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.
This error message appears when the sample concentration
exceeds 400 ppm.
The used standard solution is wrong.
This error message appears when the input readings (mV)
exceed the input limits (0÷1000mV).
12 MI456 Minititrator for Wine Analysis
pH Calibration Messages
This screen appears each time the meter enters pump or
pHcalibration mode by pressing the CAL button.
This screen appears when the pH calibration is started by
pressing the pH button. Pressing again pH or the CAL button,
the pH calibration is aborted and the instrument returns to the
main screen.
This prompt appears for a few seconds before returning to the
main screen, when the pH calibration is done.
The “WRONG” “ ” / “WRONG” “ “ tags alternatively blinking
appear when the buer solution is not correct or when the
probe is wrong. Clean the electrode by following the Cleaning
Procedure or check the quality of the buer in order to continue
the pHcalibration.
Press the CAL or pH button to leave pH calibration mode.
GENERAL TIPS FOR AN ACCURATE MEASUREMENT 13
pH End Point Setup Messages
This screen appears when the meter is in main screen and the
pH button is pressed. Press the CAL button in order to change
the end-point. Each time the pH button is pressed the end point
value is changed and the meter returns to the main screen.
Titration Messages
This screen appears each time the minititrator enters
TITRATION mode. Press the START STOP button in order to
stop the titration and return to the main screen.
The titration result, expressed as concentration of tartaric
acid in g/L, is displayed at the end of the titration process.
Press the START STOP button to return to the main screen.
This error message appears when the input reading
(pH, temeprature) exceeds the input limits.
This screen appears when the evaluated concentration is
out of range.
7. GENERAL TIPS FOR AN ACCURATE MEASUREMENT
The instructions listed below should be carefully followed during testing to ensure best
accuracy.
yPurge the peristaltic pump to have fresh titrant when starting a new analysis or
calibration.
yCalibrate the peristaltic pump before performing an analysis.
yAnalyze the wine immediately after the sample is obtained.
14 MI456 Minititrator for Wine Analysis
8. PUMP CALIBRATION PROCEDURE
Warning: The calibration of the pump must be performed each time the pump tube,
the reagent bottle or the pH electrode is changed. It is recommended to perform the
pump calibration before each set of measurements.
yUse the 2000 µL automatic pipette to add exactly 2 mL of Mi556-001 Standard to the
100 mL beaker.
yFill the beaker up to the 50 mL mark with deionized water, place the stirrer bar into
the beaker and then place the beaker in the appropriate place on the minititrator top.
yPlace the electrode holder on the top of the beaker and secure by turning clockwise.
yImmerse the pH and the temperature probe approximately 2 cm (0.8“) into the sample
to be tested while paying attention to not touch the stir bar.
yInsert the dosing tip in the appropriate holder place and pay attention to not be
immersed into solution.
50 mL
pH CALIBRATION PROCEDURE 15
yAfter sample preparation, press the CAL button to enter the pump calibration mode.
The CAL tag will start blinking.
yPress PUMP in order to start the pump calibration.
yAt the end of the calibration, “done” appears for a few seconds and the meter returns
to the measurement mode.
9. pH CALIBRATION PROCEDURE
The pH calibration must be performed each time the pH electrode is changed.
yTurn the instrument ON using the power switch from the rear panel of the instrument.
yFill the 100 mL beaker up to the 50 mL mark with Buer Solution 1 (7.00 pH) or Buer
Solution 2 (8.20 pH).
or50 mL
7.00 pH 8.20 pH
50 mL
yPlace the pH electrode into solution. Press CAL button. The CAL tag will appear blinking.
yPress pH in order to start the electrode calibration.
yAt the end of the calibration procedure “done” appears for a few seconds and then the
meter automatically returns to measurement mode.
16 MI456 Minititrator for Wine Analysis
10. MEASUREMENT PROCEDURE
Warning: Make sure the instrument has been calibrated (pH and pump calibration)
before performing a wine sample analysis.
yUse the 2000 µL automatic pipette to add exactly 2 mL of wine sample to the 100mL
beaker.
yFill the beaker up to the 50 mL mark with deionized water, place the stirrer bar into
the beaker and then place the beaker in the appropriate place on the minititrator top.
yPlace the electrode holder on the top of the beaker and secure by turning clockwise.
yImmerse the pH and the temperature probe approximately 2 cm (0.8“) into the sample
to be tested while paying attention to not touch the stir bar.
yInsert the dosing tip in the appropriate holder place and pay attention to not be
immersed into solution.
Wine Sample50 mL
PUMP TUBE REPLACEMENT 17
yPress the START STOP button to start the titration. The display will show “----” during
titration, along with stirrer and pump tags blinking on the LCD, and 7.00 or 8.20 pH
buer on the secondary display.
yAt the end of the titration, the Total Titratable Acidity concentration is displayed ing/L.
Note: If the end-point is not reached or it is not recognized because of the noisy
solution, an error message will be displayed.
11. PUMP TUBE REPLACEMENT
To remove the tube of the peristaltic pump follow next steps:
yDetach the old tube system from the reagent bottle.
yGrasp one fixing ring of the peristaltic pump tube.
yPull the tube until it’s taken out from its location.
yRemove the other side of the tube.
To mount the new peristaltic pump tube follow next steps:
yPosition one peristaltic pump fixing ring on its location.
yStretch the tube over the peristaltic pump cylinders.
yFix the second pump fixing ring on its location.
yAttach the tube to the reagent bottle.
Note: Purge the peristaltic pump until drops of reagent appears on the dosing tip by
pressing the PUMP button.
18 MI456 Minititrator for Wine Analysis
12. FUSE REPLACEMENT
To change the fuse follow next steps:
yDisconnect the power cord from the rear panel of the instrument.
yPull out the fuse holder located near the power cord connector.
yReplace the fuse with a similar one.
yPush the fuse holder with the fuse in the appropriate place.
ELECTRODE CONDITIONING & MAITENANCE 19
13. ELECTRODE CONDITIONING & MAITENANCE
Preparation Procedure
Remove the protective cap of the pH electrode (MA919B/1).
Do not be alarmed if salt deposits are present. This is normal with electrodes. They will
disappear when rinsed with water.
During transport, tiny bubbles of air may form inside the glass bulb aecting proper
functioning of the electrode. These bubbles can be removed by “shaking down” the
electrode as you would do with a glass thermometer.
If the bulb and/or junction is dry, soak the electrode in MA9015 Storage Solution for at
least one hour.
If the filling solution (electrolyte) is more than 2½ cm (1”) below the fill hole, add MA9011
3.5M KCl Electrolyte Solution. For faster response, unscrew the fill hole screw during
measurements.
20 MI456 Minititrator for Wine Analysis
Storage Procedure
To minimize clogging and assure a quick response time, the glass bulb and the junction
of the electrode should be kept moist and not allowed to dry out.
Replace the solution in the protective cap with a few drops of MA9015 Storage Solution
or, in its absence, Filling Solution (MA9011). Follow the Preparation Procedure before
taking measurements.
Note: Never store the electrode in distilled or deionized water.
Periodic Maintenance
Inspect the electrode and the cable. The cable used for connection to the instrument
must be intact and there must be no points of broken insulation on the cable or cracks on
the electrode stem or bulb. Connectors must be perfectly clean and dry. If any scratches
or cracks are present, replace the electrode. Rinse o any salt deposits with water.
Probe Maintenance
yRefill the reference chamber with fresh electrolyte (MA9011).
yAllow the electrode to stand upright for 1 hour. Follow the Storage Procedure above.
CLEANING PROCEDURE
yWine deposits: Soak in Milwaukee MA9016 cleaning solution for 1 hour
yWine stains: Soak in Milwaukee MA9016 cleaning solution for 1 hour
IMPORTANT: After performing any of the cleaning procedures, rinse the electrode
thoroughly with distilled water, refill the reference chamber with fresh electrolyte
and soak the electrode in MA9015 Storage Solution for at least 1 hour before taking
measurements.
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