Sensitive determination of Se(IV) and tSe in rice and water samples using L-cysteine modified carbon paste electrode-based electrolytic hydride generation and atomic fluorescence spectrometry analysis

This work illustrates an accurate method for determination of Se by electrolytic hydride generation technique based on a novel carbon paste electrode for sample introduction combined with atomic fluorescence spectral analysis. The studies show that Se(IV) can be converted efficiently to SeH2 on an (L)-cysteine modified carbon paste electrode (CMCPE), which has never been reported before. Significantly, generation from Se(IV) implies that the use of carbon paste electrode-based electron-induced hydride generation system to achieve efficiency is almost 90% to that obtained by chemical hydride generation, and the response obtained from CMCPE is 2 and 3 times of that from the Pb and graphite electrode, respectively. Results also display that the lifetime and the stability of the CMCPE is superior to that of (L)-cysteine ornamented graphite electrode fabricated by covalently bonding. Under the optimal conditions, a low concentration limit of detection 0.065 mu g L-1 of Se(IV) is achieved. The repeatability denoted as % RSD is 2.2% for 1.0 mu g L-1 Se(IV). The utility of the studied method is compared with certified reference materials as well as several edible samples. The advantages and limitations of this method, compared with existing techniques, are also discussed.