Arsenic speciation by hydride generation-atomic absorption spectrometry coupled with a cryogenic trap

Hydride generation-atomic absorption spectrometry (HG-AAS) combined with a cryogenic trap was utilized in arsenic speciation. The set-up of the HG-AAS system consists of a peristatic pump, PE 3100 atomic absorption spectrometer, 2 Variac transformers, and a strip chart recorder. Mixed solutions of inorganic arsenic (As lll), monomethyl arsenic acid (MMAA), and dimethyl arsenic acid (DMAA) were converted to their corresponding volatile hydrides and the generated arsines trapped and separated according to their volatility: inorganic arsine first, then methylarsine, followed by dimethylarsine. HG-AAS system parameters, like flow rates, were optimized for quantitative analysis of the different arsenic species. Linear responses were obtained in the nanogram levels. The technique was applied to arsenic speciation in some seawater and seaweed samples. The seawater samples contained an average of 1.5 ng/mL inorganic As. The seaweed sample analyzed contained inorganic arsenic species and DMAA totalling 0.5 μ total As/g of seaweed. (Author)