Studies on the Efficiency of Hydrogen Selenide Generation with Different Acid Media by Continuous Flow Hydride Generation Atomic Absorption Spectrometry

摘要

The efficiency of hydrogen selenide generation by HCl, HBr, H2SO4, HClO4 and HNO3 was studied with varying NaBH4 concentrations by continuous flow hydride generation AAS. HBr showed higher efficiency (≈20%) than the conventionally used HCl. The optimum concentration of reagents were 5 M HBr, with 0.5% NaBH4 and 6 M HCl with 1% NaBH4. The efficiency followed the order HBr>HCl>HClO4SO4. The sensitivity and detection limits were 0.16 µg L−1 and 0.15 µg L−1 with HBr, and, 0.19 µg L−1 and 0.17 µg L−1 with HCl. The calibration graphs were linear in the range of 2–25 µg L−1 for both the acids. Se6+ was reduced to Se4+ in 1 M HCl with the addition of solid KBr (4% final solution) with 60 minutes heating at 70 °C and compared to the commonly used 6 M HCl with 15 minutes boiling. Pre-reduction with KBr showed signal enhancement by 5 to 10% in the range 2–25 µg L−1 of Se4+. The application of the method to SRM 1640 demonstrated that results were in good agreement with the certified values. Groundwater samples from a suburban area were analyzed and reported.