Abstract
A hydride generation-atomic absorption method for the precise and sensitive determination of arsenic, selenium and antimony in sediments is described. The environmental certified reference materials sample was digested with HF/HNO3/HCIO4/KMnO4, and the residue was disolved in dilute hydrochloric acid with heating 1 hour on a boiling water bath. For As and Sb, potasium iodide-ascorbic acid were added to prereduction and acidfied sample solutions with hydrochloric acid were lead to automated hydride generator and determined As, Se and Sb by atomic absorption spectrometer individually.
Analytical results of As, Se and Sb obtained by proposed method are in good agreement with the certified or reference values for the CRMs included BCSS-1, Pond Sediment, NIST 1646 and SL-1, the relative standard deviations are less than 5%. Determination of analytes could be performed with only one digestion procedure and small modification of pretreatment for these hydrides generation.
On the other hand, several acid digestion procedures were examined for routine analysis of environmental samples, the best results which gave high recoveries were obtained by using the procedure with HNO3/HClO4/KMnO4 for As, Se and with hydrochloric acid for Sb. Application of the procedure with HNO3/HClO4/KMnO4 for the determination of Sb resulted in unsatisfactory recoveries, it was suggested that antimony formed insoluble compounds in dilute hydrochloric acid, and sorbed on the residue of sediment.
Ratios of analytical results of analytes for 4 CRMs obtained by recommended acid digestion to obtained by HF/HNO3/HClO4/KMnO4 procedure were about 0.70-0.90 for arsenic, larger than 0.90 for selenium and almost 0.87 for antimony respectively.
The limits of determination of anlytes are 0.0375 μg·g-1 for 2g of sediment.
