Analysis of amine-containing phosphonates in detergent powders by anion-exchange chromatography with pulsed amperometric detection

A report on an ion chromatographic method with pulsed amperometric detection (PAD) on a gold electrode is presented. The sample preparation step was extensively studied and optimized. Measurement of Dequest 204/206 in detergent powder requires a special sample pretreatment, in order to prevent oxidation of Dequest by bleach. Addition of sulphite reduces and thus inactivates the bleach. PAD is a sensitive and selective detection technique, which is applicable to amine-containing sequestrants. Concentrations of 25 mg/l (i.e., 0.5% Dequest in the detergent powder) can easily be quantitated. Other matrix compounds are completely separated from Dequest, by using gradient elution.