Analytical Sciences

Influence of Speciation on the Response from Selenium to UV-Photochemical Vapor Generation

Toshihiro SUZUKI,*1,*2 Ralph E. STURGEON,*1 Chengbin ZHENG,*3 Akiharu HIOKI,*2 Tetsuya NAKAZATO,*4 and Hiroaki TAO*4

*1 National Research Council Canada, Measurement Science and Standards Portfolio, Montreal Road, Ottawa, K1A0R9, Canada
*2 National Metrology Institute of Japan, National Institute of Advanced Industrial Science and Technology, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8563, Japan
*3 College of Chemistry, Sichuan University, Chengdu, Sichuan 610064, P. R. China
*4 Research Institute for Environmental Management Technology, National Institute of Advanced Industrial Science and Technology, 16-1 Onogawa, Tsukuba, Ibaraki 305-8569, Japan

By exposure to appropriate UV intensities, rapid and quantitative oxidation/reduction of inorganic selenite, selenate and several organoselenium compounds representative of those of biochemical/metabolic interest, including selenomethionine, selenobetaine, L-selenocystine, selenomethylselenocysteine, γ-glutamyl-seleno-methylselenocysteine and selenocystamine, is achieved. In the presence of acetic acid, quantitative conversion to volatile SeH₂ and SeCO occurs using a flow-through system comprising a highly efficient 40 W UV lamp for oxidation in tandem with a lower power 8 W UV photocatalytic reactor utilizing a thin-film coating of titania. The volatile reduced species are detected by atomic absorption spectrometry using a heated quartz tube atomizer. Direct photochemical conversion of selenite, selenomethionine, L-selenocystine, γ-glutamyl-Se-methylselenocysteine and selenocystamine occurs in the presence of 5% acetic acid, following exposure to an 8 W UV field, to yield volatile detectable species, whereas selenobetaine and selenate are unresponsive unless the latter is first subjected to oxidation by exposure to a highly efficient 40 W UV lamp and the selenate reduced in the presence of titania.

J-STAGE: View this article in J-STAGE