Principle Of Operation - Hanna Instruments HI84529 Instruction Manual

4. PRINCIPLE OF OPERATION

The methodology for titratable acidity in dairy products is based on neutralization reaction where
the acids in the sample (i.e. lactic acid) reacts with a base (i.e. sodium hydroxide) to produce water:
+ ¯
H +OH H O
2
In an ideal solution, the endpoint of an acid titration corresponds stoichiometrically to the complete
neutralization of the acids present.
This endpoint for this reaction can be determined visually using a color indicator (i.e. phenolphthalein),
however this endpoint becomes very objective in opaque and colored samples. The HI84529 removes
this issue by titrating to a fixed pH endpoint that can be set by the user. The HI84529 can be
customized to meet individual needs with samples titrated by mass or by volume, in two different
ranges, with diluted and non-diluted (low range only). For precise analysis the sample size, volume
of titrant added and titrant concentration must be known.
The HI84529 Titratable Acid in Dairy Products Mini Titrator utilizes a simple sample preparation, a high
quality dosing pump for titrant additions, potentiometric endpoint determination and instantaneous
computations. To maintain the high accuracy of the mini titrator a simple pump calibration is required.
The pump calibration uses a known quantity of a known solution to compensate for changes in the
dosing system, this procedure should be performed regularly.
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