Semi‐micro determination of total phosphorus in soils, sediments, and organic materials: A simplified perchloric acid digestion procedure

Abstract

A semi‐micro modification of perchloric acid digestion method for the determination of total P in soils, sediments, and organic materials is described. Samples are digested for 30 minutes with nitric acid at 115 °C and then for 2 hours with perchloric acid at 170 °C in an aluminum heating block. After dilution, samples are hydrolyzed at 100 °C for 1 hour in order to decompose pyrophosphate, and the liberated orthophosphate is determined without a neutralization step by the phosphomolybdate blue method of Murphy and Riley (1962). Comparability with the method of Sommers and Nelson (1972) is demonstrated using nine samples of different types. The same reaction conditions of digestion and color development as in the determination of total P in waters (Kopáček and Hejzlar, 1993) enable a comparable estimate of total P in solid and water samples in complex environmental studies.