The HI84529-50 is a 120 mL bottle of alkaline titrant solution used for the Low Range 20  range that determines 0.01 to 0.20% lactic acid in dairy products.

The methodology for titratable acidity in dairy products is based on a neutralization reaction of the acids in a sample (e.g., lactic acid) with a base (e.g., sodium hydroxide) to produce water:

H++OH- → H2O

In an ideal solution, the endpoint of an acid titration corresponds stoichiometrically to the complete neutralization of the acids present. The endpoint for this reaction can be determined visually using a color indicator (e.g., phenolphthalein); however, this endpoint becomes very subjective in opaque and colored samples such as milk. The HI84529 removes this issue by titrating to a fixed pH endpoint that is potentiometrically determined by the FC260B half-cell pH electrode and HI5315 half-cell reference electrode.

Replacement reagents required to operate the HI84529 include: