BACKGROUND: Atomic Fluorescence Spectrometry(AFS) has advantages of high sensitivity, simple structure and easy operation, but the digestion process of the standard analysis method for determination of Se in soil is cumbersome and readily produces interference.OBJECTIVES: To evaluate the applicability of Se determination in soil and sediment by water bath digestion/AFS, and uncover the main interference and elimination methods.METHODS: Based on the standard method of GB/T 22105-2008, boiling water bath of aqua regina was used to digest Se in soil and sediment. Four treatments, including Fe^3+, concentrated hydrochloric acid, Fe^3+with concentrated hydrochloric acid, and water bath solution, were used to eliminate the interference of Cu^2+ and Pb^4+.RESULTS: The detection limit of Se by this method was 0.008 mg/kg, the relative standard deviation of the test reference materials was 0.5%-11%, and the relative error was-16.3%-9.5%, better than the detection limit(0.01 mg/kg), precision(0.79%-23.1%) and accuracy of the industry standard HJ 680-2013.CONCLUSIONS: According to the experiment, it is proposed to add concentrated hydrochloric acid to the water bath digestion solution without adding thiourea-ascorbic acid. By increasing the acidity and Cl^- concentration of the solution and keeping the concentration of hydrochloric acid in the sample higher than 23%, the reduction of Cu^2+ to Cu^0 and Pb^4+ to form PbH4 can be inhibited. The negative interference of Cu and the positive interference of Pb are effectively reduced, and the precision and accuracy of Se measured by AFS are improved.
Rock and Mineral Analysis
water bath digestion
Atomic Fluorescence Spectrometry