OXALATE DETERMINATION IN SOILS USING ION CHROMATOGRAPHY

A method was developed for determining oxalate in soils with variable levels of CaCO3. The soils were extracted with 1.0 M HCl for varying periods of time at 80-degrees-C and room temperature, as well as being extracted as saturation pastes. Oxalate in the extracts was determined on and ion chromatograph, with special care taken in the cleaning of the column and suppressor. The eluant was 0.85 mM NaHCO3 and 0.90 mM Na2CO3. Recovery of oxalate from CaC2O4 spiked samples extracted with HCl ranged from 16 to 104%. Each soil required a different extraction time to obtain maximum release of oxalate. Soil with the greatest CaCO3 content yielded the lowest oxalate recovery. Oxalate content of unspiked samples was also determined. Recovery of oxalate as CaC2O4 from the saturation pastes ranged from 0.1 to 25.0%. Detection limits were 15-mu-g L-1 in the HCl extracts and 22-mu-g L-1 in the saturation-paste extracts.