Abstract
Recently, speciation of selenium has attracted wide attention not only because the narrow threshold concentration range between deficiency and toxicity, but also its complexity in phisco-chemical form presenting in various environment and biological media. In general, the major soluble forms of selenium in nature waters have been proven to be selenite and selenate. The concentrations of selenium species in nature waters are extremely low; therefore, it is of great important to develop a sensitive and selective method for the study of the fate of selenium species in aqueous environment. According to literatures, undoubtedly, HPLC-ICP-MS hyphenated technique is one of the most sensitive method for the determination of trace selenium species. However, the analytical sensitivity of ICP-MS for selenium is highly limited by the high ionization energy (9.75 eV) of selenium and the inferior transport efficiency (mostly 2–3%) provided by traditional sample introduction systems. To compensate for the inferiority of HPLC-ICP-MS system, hydride generation (HG) technique has been successfully used to interface chromatography and spectrometers by enhancing analyte transportation efficiency and sensitivity. Recently, a novel photo-catalyst reduction device (PCRD) was developed, which has been verified as an efficient and high-performing technique for selenite and selenate detection. Because the PCRD was constructed by a PTFE tube, in this study, we intended to develop a PMMA (polymethylmethacrylate) Chip-base photo-catalyst reduction device (PC2RD) to improve the light transmission and sensitivity of detection. After the fabrication of meso-fluidic chip by CO2-Laser engraver, a UV lamp with 365 nm wavelength was used for the irradiation. Based on the experimental results, PC2RD system could improve the transport efficiency of analyte selenium species by 20%, comparing to PCRD system. Moreover, it merely needed 29s to transform inorganic selenium into gaseous selenide. The limit of detection of Se(Ⅳ) and Se(Ⅵ) were 4.9 and 3.9 ng/L, respectively. Based on the achieved analytical results, it indicated that our developed HPLC-PC2RD-ICP-MS system is a fast, simple and high sample transportation efficiency method, and has the ability to determine different selenium species in natural waters.