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

Abstract

In order to confirm the solution structure of [(GS) 2 AsSe] À (GS = glutathione), we have investigated the retention behaviour of a [(GS) 2 AsSe] À /oxidized glutathione (GSSG) mixture on a Sephadex G-25 (SF) column with Tris buffers (0.1 mol dm À3 , pH 8.0) containing various surfactants at concentrations above the critical micellar concentration (CMC): hexadecyltrimethlammonium bromide (HDTAB; 30, 40 and 50 mmol dm À3 ); dodecyltrimethylammonium bromide (DDTAB; 50 mmol dm À3 ); and sodium lauryl sulfate (SLS; 50 mmol dm À3 ). 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) 2 AsSe] À and GSSG. The chromatograms obtained with 50 mmol dm À3 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) 2 AsSe] À .

The potential of lentil (Lens culinaris L.) as a whole food for increased selenium, iron, and zinc intake: preliminary results from a 3 year study

“…The selenoproteins are thought to discharge the nutritional essentiality of Se, the bioavailability of which is a function of its liberation from foods to be metabolized to selenoprotein-bound SeCys. Suboptimal Se status in humans has been associated with increased risk of cancer, and HIV/AIDS and other viral diseases (measles, hepatitis, influenza) including an endemic cardiomyopathy, Keshan Disease, in China (Combs 2001;Gailer et al 2000;Rayman 2002). Supranutritional intakes of Se have been shown to reduce cancer risk (Clark et al 1996), and hundreds of studies with animal tumor models have shown Se to be antitumorigenic through several cellular and metabolic mechanisms (Combs and Lu Junxuan 2001;Combs and Lu 2006;Jackson and Combs 2008).…”

Biliary Excretion of [(GS)2AsSe]- after Intravenous Injection of Rabbits with Arsenite and Selenate

“…We have shown that this species is formed in vivo and subsequently excreted in bile (12)(13)(14). [(GS) 2 AsSe] -therefore represents a fundamental molecular link between the metabolism of arsenite and selenite in mammals and thus is of considerable toxicological importance (12).…”

Simultaneous arsenic‐ and selenium‐specific detection of the dimethyldiselenoarsinate anion by high‐performance liquid chromatography–inductively coupled plasma atomic emission spectrometry

“…Additionally, the latter retention strategy would most likely also minimize a possible decomposition of [(CH 3 ) 2 As(Se) 2 ] − during the chromatographic separation process, as was previously observed with the structurally related species [(GS) 2 AsSe] − on anion-exchange columns. 6 Since the ultimate goal was to develop a chromatographic method for the identification of [(CH 3 ) 2 As(Se) 2 ] − in biological samples, PBS buffers (0.01 mol dm −3 ) were investigated as mobile phases (the utilization of other mobile phases could lead to the decomposition of [(CH 3 ) 2 As(Se) 2 ] − on the chromatographic system). The decomposition of [(CH 3 ) 2 As(Se) 2 ] − below pH 7.0, however, required a mobile phase with pH > 7.0.…”

“…14,15 The simultaneous exposure of the general population to dimethylarsinate and dietary selenium compounds could, therefore, lead to the in vivo formation of [(CH 3 ) 2 As(Se) 2 During the development of an SEC-ICP-AES method for the identification of [(GS) 2 AsSe] − in aqueous solutions, we previously noticed that the stationary phase must be chosen carefully in order to prevent the decomposition of this species during the chromatographic separation. 6 In view of these findings, and with regard to the similar chemical properties of [(GS) 2 AsSe] − and [(CH 3 ) 2 As(Se) 2 ] − (both are oxygen sensitive and decompose below pH 7.0), 6,10 the development of an HPLC method for the identification of [(CH 3 ) 2 As(Se) 2 ] − requires that this species can be passed through the stationary phase unchanged and structurally intact. [(CH 3 ) 2 As(Se) 2 ] − contains two As-C and two As-Se single bonds.…”