The HI84530-51 is a 120 mL bottle of alkaline titrant solution that is used for high range (300 to 4000 mg/L as CaCO₃) determination of acidity in water.

The HI84530 mini titrator is designed to determine the acidity of waters by potentiometric titration in both a low range (15 to 400 mg/L as CaCO3) and high range (300 to 4000 mg/L as CaCO3). Both total and strong acidity can be determined by the HI84530. If the measured pH is lower than 3.7 both total and strong acidity can be determined. If the sample is greater than pH 3.7 then only total acidity can be determined.

The endpoint of an acid base titration corresponds 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 HI84530-60 reagent.

Replacement reagents required to operate the HI84530 include:

* Used with samples containing hydrolyzable salts or polyvalent cations (such as chromium, iron, manganese)