Ion-Exchange Method for Analysis of Four Arsenic Species and its Application to Tap Water Analysis

Abstract

Arsenic (III), arsenic (V), monomethylarsonic acid (MMA), and dimethylarsinic acid (DMA) were separated by ion-exchange chromatography. The elution sequence was as follows: 1.5 M ammonia followed by 0.12 M hydrochloric acid yielding As(III); 1 M hydrochloric acid followed by water yielding first As(V) and then MMA. Detection was performed by hydride generation-atomic absorption spectrometry. The possible interferences of 13 metallic ions have been studied and none of them was found to interfere. The method provides good linearity, precision, accuracy, and sensitivity. It has been applied to the speciation of arsenic in tap water samples from North West of Spain (a region about 29500 Km²).