Single-Column Ion Chromatography: IV. Determination of Arsenate in Soils
- H. C. Mehra and
- W. T. Frankenberger
A method has been developed for the determination of arsenate (AsO3−4) in aqueous soil extracts by single-column ion chromatography (SCIC) at trace levels. The eluent stream consisted of 6 mM p-hydroxybenzoic acid (PHBA) at pH 7.0. Separation was carried out on a low-capacity anion-exchange resin column with the anion species being quantified by conductometric detection. Resolution between AsO3−4 and PO3−4 was Rs = 1.93. The method allows precise (RSD, relative standard deviation = 1.12 to 7.87%) trace amount measurement of AsO3−4 (detection limit, 0.092 mg L−1) in the presence of Cl, NO−3, PO3−4 and SO2−4. The AsO3−4 signal becomes masked limiting separation and detection when PO3−4 exceeds 30 mg L−1. Under the conditions described, arsenite (AsO3−3) was not detected. Analysis of aqueous soil extracts for AsO3−4 by SCIC agrees closely with those values obtained by atomic absorption spectrometry and inductively coupled plasma emission.
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