LABEC M-MIA-A - Manual (Page 87)

Ultrasonic milk analyser
reason it is always a good idea to have a back-up electrode on hand to avoid
any system down time.
3. Buffer Solutions
Buffers are solutions that have constant pH values and the ability to resist
changes in that pH level. They are used to calibrate pH measurement
system.
PH buffer solution description ( Pharmacopoeia standard)
Use only this types standard buffers for calibration!
Description
pH 7.00±0,01/20ºC pH 4.00±0,01/20ºC
Composition Potassium dihydrogen
phosphate, Di-sodium
hydrogen phosphate
Borax, Sodium
hydroxide solution
Temperature
parameters
10ºC - 7.06
25ºC - 6.99
20ºC - 7.00
30ºC - 6.98
40ºC - 6.95
50ºC - 6.91 10ºC - 4.00
25ºC - 4.00
20ºC - 4.00
30ºC - 4.00
40ºC - 4.00
50ºC - 4.05
4. pH Electrode Calibration
pH Electrodes are like batteries; they run down with time and use. As an
electrode ages, its glass changes resistance. For this reason, electrodes
need to be calibrated on a regular basis. Calibration in pH buffer solution
corrects for this change.
Calibration is an important part of electrode maintenance. This assures not
only that the electrode is behaving properly but that the system is operating
correctly.
Usually pH meters require calibration at 3 specific pH values. One calibration
is usually performed at pH 7, second and third are typically performed at pH 4
and pH 10.
It is best to select a buffer as close as possible to the actual pH value of the
sample to be measured. Use standard calibration buffers that the
temperature and the sample solution are the same.
Use the operation manual for the corresponding pH meter.
Operation manual MRC.VER.01-02.10