Simultaneous multielement-specific detection of a novel glutathione-arsenic-selenium ion [(GS)₂AsSe]^- by ICP AES after micellar size-exclusion chromatography

In order to confirm the solution structure of [(GS)₂AsSe]^- (GS = glutathione), we have investigated the retention behaviour of a [(GS)₂AsSe]^-/oxidized glutathione (GSSG) mixture on a Sephadex G-25 (SF) column with Tris buffers (0.1 mol dm^-3, pH 8.0) containing various surfactants at concentrations above the critical micellar concentration (CMC): hexadecyltrimethlammonium bromide (HDTAB; 30, 40 and 50 mmol dm^-3); dodecyltrimethylammonium bromide (DDTAB; 50 mmol dm^-3); and sodium lauryl sulfate (SLS; 50 mmol dm^-3). An inductively coupled plasma atomic emission spectrometer (ICP AES) provided simultaneous on-line detection of arsenic, selenium and sulfur in the column effluent. The chromatographic retention behaviour was used to investigate the association of both compounds with the positively charged micelles (HDTAB and DDTAB mobile phases). The relative strength of association with the micelles provided insight into the effective negative charge on [(GS)₂AsSe]^- and GSSG. The chromatograms obtained with 50 mmol dm^-3 HDTAB indicated that two glutathione molecules are associated with the elution of an arsenic-selenium compound. Combined, these chromatographic data strongly support the spectroscopically derived solution structure of [(GS)₂AsSe]^-. Copyright (C) 2000 John Wiley and Sons, Ltd.