Determination of inorganic arsenic and organic arsenic compounds in marine organisms by hydride generation/cold trap/gas chromatography— mass spectrometry

Abstract

AbstractThe behavior of arsenite, methylarsonic acid, dimethylarsinic acid, trimethylarsine oxide, dimethyl‐R‐arsine oxides, and trimethyl‐R‐arsonium compounds (R = carboxymethyl, 2‐carboxyethyl, 2‐hydroxyethyl) toward sodium borohydride and hot aqueous sodium hydroxide was investigated. The arsines obtained by sodium borohydride reduction of the undigested and digested solutions were collected in a liquid‐nitrogen cooled trap, separated with a gas chromatograph, and detected with a mass spectrometer in the selected‐ion‐monitoring mode. The investigated arsenic compounds were stable in hot 2 mol dm−3 sodium hydroxide except arsenobetaine [trimethyl(carboxymethyl)arsonium zwitterion] that was converted to trimethylarsine oxide, and dimethyl(ribosyl)arsine oxides that were decomposed to dimethylarsinic acid. Hydride generation before and after digestion of extracts from marine organisms allowed inorganic arsenic, methylated arsenic, arsenobetaine, and ribosyl arsenic compounds to be identified and quantified. This method was applied to extracts from shellfish, fish, crustaceans, and seaweeds.