Hydroxylamine and Ammonium Oxalate Solutions as Extractants for Iron and Aluminum from Soils

Abstract

AbstractA comparison was made of acid hydroxylamine and acid ammonium oxalate methods for extracting Fe and Al from three clay mineral (chlorite) samples and 27 soil samples. Although the hydroxylamine solution was more acid than the oxalate solution, the hydroxylamine extraction did not increase dissolution of the chlorites markedly. It was concluded that overnight hydroxylamine extraction at room temperature using a 1:250 soil‐to‐solution ratio can be used as an alternative method to the 4‐h oxalate extraction method with the 1:40 soil‐to‐solution ratio commonly used in soil studies. This conclusion was based on the following reasons: (i) the results from both methods were comparable for nearly all samples; (ii) hydroxylamine solutions were more easily analyzed than oxalate solutions by atomic absorption analysis; (iii) overnight hydroxylamine extraction at room temperature required no specialized heating baths with compatible shaking equipment and is therefore suitable for most laboratories.