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

In order to confirm the solution structure of [(GS)(2)AsSe](-) (GS = glutat hione), we have investigated the retention behaviour of [(GS)(2)AsSe](-)/ox idized 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 concentra tions above the critical micellar concentration (CMC): hexadecyltrimethlamm onium bromide (HDTAB; 30, 40 and 50 mmol dm(-3)); do decyltrimethylammonium bromide (DDTAB; 50 mmol dm(-3)); and sodium lauryl sulfate (SES; 50 mmol d m(-3)). An inductively coupled plasma atomic emission spectrometer (ICP AES ) provided simultaneous on-line detection of arsenic, selenium and sulfur i n the column effluent. The chromatographic retention behaviour was used to investigate the association of both compounds with the positively charged m icelles (HDTAB and DDTAB mobile phases). The relative strength of associati on with the micelles provided insight into the effective negative charge on [(GS)(2)AsSe](-) and GSSG. The chromatograms obtained with 50 mmol dm(-3) HDTAB indicated that two glutathione molecules are associated with the elut ion of an arsenic-selenium compound. Combined, these chromatographic data s trongly support the spectroscopically derived solution structure of [(GS)(2 )AsSe](-). Copyright (C) 2000 John Wiley Rt Sons, Ltd.