Double hydride generation gaseous phase enrichment with flow injection on-line automatic preparation for ultratrace amounts of total selenium determination by atomic fluorescence spectrometry

摘要

A double hydride generation technique was developed and successfully used for the determination of total ultratrace amounts of selenium by atomic fluorescence spectrometry (AFS). In this technique, the acid digested sample solution was used for the generation of selenium hydride first, after which, the SeH2 formed was reacted with, and absorbed in, a small volume of alkaline solution (0.5 mol L-1 NaOH + 0.05 mol L-1 H2O2), in which automated organic selenium digestion by the flow injection technique was pursued. The alkaline solution with the selenium absorbed was mixed with the reductant and then acidified to achieve hydride generation for the second time. The concentration factor depends on the volume ratio of the sample and the alkaline solution. Selenium hydride was atomized in a quartz atomizer with a mini-hydrogen diffusion flame and detected by AFS. Under the conditions employed, a detection limit of 2-6 pg Se mL(-1) and 2.8% relative standard deviation (RSD) (with 1 ng mL(-1) Se, n = 11), and 12% RSD (with 0.05 ng mL(-1) Se, n = 7) were obtained by this enrichment technique and AFS detection.