The HI84430-55M is a 230 mL bottle of pump calibration solution that is used for both low and high range determination of acidity in water.

 The determination of water acidity is based on the neutralization of all acidic species contained in water samples by titration with a basic titrant solution:

H⁺ + OH^- → H₂O

The endpoint of an acid base titration corresponds stoichiometrically to the complete neutralization of the acids present. Water acidity results from strong and weak acids as well as from the hydrolysis of salts. Due to these more complex mixtures, endpoints for water acidity are arbitrarily fixed on practical considerations. Unpolluted surface waters contain carbon dioxide as the main acidic component, and titration of these samples corresponds to the stoichiometric neutralization of carbonic acid with sodium hydroxide. The titration to pH 8.3 represents total acidity. The titration to pH 3.7 represents strong acidity from polluted water. If the samples are suspected to contain hydrolyzable salts or polyvalent cations (such as chromium, iron, manganese), it is necessary to pretreat the samples with HI84430-58 reagent.

Titratable acidity in waters, as performed on the HI84430 mini titrator, utilizes a simple sample preparation, a high quality titrant dosing pump, potentiometric endpoint detector, and automatic computations. To maintain the high precision of the titrator, a simple pump calibration procedure is required. A change of measurement range requires a different titrant along with a pump recalibration. The pump calibration involves the analysis of a known volume of a known solution and compensates for changes in pump dosing that may occur due to many factors including tube stretching or aging. This procedure should be performed regularly with the HI84430-55M pump calibration solution to accurately determine acidity levels in water.

Replacement reagents required to operate the HI84430: