Volatile analytes formed from arsenosugars: determination by HPLC-HG-ICPMS and implications for arsenic speciation analyses.

Abstract

It is generally accepted that the use of the hydride generation method to produce volatile analytes from arsenic compounds is restricted to the two inorganic forms (As(III) and As(V)) and the three simple methylated species methylarsonate (MA), dimethylarsinate (DMA), and trimethylarsine oxide. We report here that arsenosugars, major arsenic compounds in marine organisms, produce volatile analytes by the hydride generation (HG) method without a prior mineralization/oxidation step and that they can be quantitatively determined using HPLC-HG-ICPMS. The hydride generation efficiency depends on the type of hydride generation system and is influenced by the concentration of HCl and NaBH(4). For the four arsenosugars investigated, the hydride generation efficiencies were approximately 21-28% (or 4-6%, depending on the HG system) that obtained for As(III) under conditions optimized for As(III). This hydride efficiency was less than that shown by MA ( approximately 68% relative to As(III)) and DMA ( approximately 75%) but greater than that displayed by As(V) ( approximately 18%). Analysis of two species of brown algae, Fucus serratus and Hizikia fusiforme, by HPLC-HG-ICPMS produced results comparable with those obtained from other techniques used in our laboratory (HPLC-ICPMS and LC-ESMS for F. serratus) and with results from other laboratories taking part in a round robin exercise (H. fusiforme). This study shows for the first time the quantitative determination of arsenosugars using the hydride generation method without a decomposition step and has considerable implications for analytical methods for determining inorganic arsenic based on the formation of volatile hydrides.