Speciation of Se(IV) and the selenoamino acids by high-performance liquid chromatography–direct hydride generation–atomic fluorescence spectrometry

Abstract

The speciation of selenocystine (SeCys), selenomethionine (SeMet), selenoethionine (SeEt) and Se(IV) was performed by on-line coupling of high-performance liquid chromatography (HPLC) and atomic fluorescence spectrometry (AFS) with hydride generation (HG) as high efficiency sample introduction system. Reversed-phase liquid chromatography was applied to separate the selenium species with 0.01 M ammonium acetate buffer (pH=4) eluent containing 0.5% (v/v) methanol and 0.1 mol l −1 of DDAB . The operating conditions for chromatographic separation (gradient elution, run time) and hydride generation (concentration of HCl and NaBH 4 solution, argon and hydrogen flow rates) were carefully optimized. The efficiency of hydride generation for all of the four species was measured. Detection limits (DLs) obtained for SeCys, SeMet, SeEt and Se(IV) are 18, 70, 96, and 16 μg l −1, respectively. The analytical performance of the method was controlled by measuring the selenium content of spiked selenium food supplements. The range of obtained recoveries is 90–110%.