Column-switching system for selenium speciation by coupling reversed-phaseand ion-exchange high-performance liquid chromatography with microwave-assisted digestion-hydride generation-atomic fluorescence spectrometry

Speciation of selenocysteine (SeCys), selenomethionine (SeMet), selenoethio nine (SeET), selenite (Se-(IV)) and selenate (Se-(VI)) has been accomplishe d using high-performance liquid chromatography, with the aid of an anion ex change column and a reversed-phase column, both connected through a six-por t switching valve. On-line microwave-assisted digestion and hydride generat ion steps were performed prior to the atomic fluorescence detection. The el ution of the seleno amino acids was accomplished in the reversed-phased col umn using water as mobile phase. Selenite and selenate were separated in th e anion exchange column, using gradient elution with an acetate buffer. The separation of the five selenium compounds took place in 15 min. The detect ion limits obtained ranged between 0.6 and 0.9 mu g l(-1).Values of r>0.998 were obtained for linear fit graphs. A commercial available urine sample w as analyzed, in which SeCys and Se-(IV) were quantified. (C) 2000 Elsevier Science B.V All rights reserved.