Photochemical alkylation of inorganic arsenic : Part 2. Identification of aqueous phase organoarsenic species using multidimensional liquid chromatography and electrospray mass spectrometry

Abstract

The alkylation of arsenic via a new photochemical pathway was investigated. Photochemical alkylation was achieved by irradiating a solution of 5 mg l⁻¹ As(III) containing 1.4 M (20% v/v) acetic acid with UV light. Water-soluble arsenic species formed during the alkylation process were separated using multidimensional LC (anion- and cation-exchange chromatography) and isolated for off-line identification by electrospray mass spectrometry (ES-MS) or on-line reverse phase LC-MS. The molecular ions of potential organoarsenic species were subjected to collision induced dissociation and identification was based on structural information obtained from fragments or by comparison of fragmentation spectra of known species. Mass Frontier software was employed to help elucidate the structures of unknown compounds. Thirteen organoarsenic species were identified, six of which are previously unreported organoarsenic species.