ION-EXCHANGE METHOD FOR ANALYSIS OF 4 ARSENIC SPECIES AND ITS APPLICATION TO TAP WATER ANALYSIS

Arsenic (III), arsenic (V), monomethylarsonic acid (MMA), and dimethyl arsinic acid (DMA) were separated by ion-exchange chromatography. The elution sequence was as follows: 1.5 M ammonia followed by 0.12 M hydr ochloric acid yielding As(III); 1 M hydrochloric acid followed by wate r yielding first As(V) and then MMA. Detection was performed by hydrid e generation-atomic absorption spectrometry. The possible interference s of 13 metallic ions have been studied and none of them was found to interfere. The method provides good linearity, precision, accuracy, an d sensitivity. It has been applied to the speciation of arsenic in tap water samples from North West of Spain (a region about 29500 Km(2)).