Direct analysis of natural waters for arsenic species by hydride generation atomic absorption spectrometry

Abstract

Selective reaction media were applied to generate hydrides of total arsenic, As(III), As(V), dimethylarsonic acid (DMA) and monomethylarsonic acid (MMA) from natural waters acidified with HCl (0.1 mol/L HCl in the sample) using reduction with 0.6% NaBH4 in a continuous flow hydride generation system: 1. 1.0 mol/L HCl in the acid channel, water samples pretreated with KI: determination of As(III) + As(V) + MMA 2. 6.0 mol/L CH3COOH in the acid channel: determination of As(III) + DMA 3. 6.0 mol/L CH3COOH in the acid channel, water samples pretreated with KI: determination of As(III) + As(V) + DMA 4. 1.0 M tartaric acid in the acid channel, water samples pretreated with KI: determination of total arsenic As(III) + As(V) + DMA + MMA With the selected medium reactions (1–4) the same response can be obtained for all arsenic species. Calibration with arsenic(III) standard solutions was applicable to the four reactions for arsenic speciation in mineral water, underground water and sea water.