Determination of sulfur fractions in soils by sequential extraction, inductively coupled plasma-optical emission spectroscopy and ion chromatography

Abstract

A method is described for the determination of sulfur species in soil samples by sequential extraction, inductively coupled plasma-optical emission spectroscopy (ICP-OES), and ion chromatography (IC). Sulfur constituents were fractionated into water-soluble, adsorbed, dilute-HCI-volatile and dilute-HCI-soluble, pyrite-associated, Hl-reducible, ester-bound and carbon-bonded sulfur. The operating conditions for each fraction were studied in detail. Inorganic sulfate and organic sulfur components in the water-soluble, adsorbed, and HCI-soluble fractions were determined by ICP-OES and IC. Digestion or decomposition of soil samples with a mixture of HNO3/HCIO4 or a mixture of HNO3/HCIO4/HF under high-pressure conditions were compared for the determination of the total sulfur. The effect of air-drying the soil on the various species of sulfur was investigated and it was found that no significant differences were observed between the field-moist and air-dried soil samples. The precision range, from 1.5 to 10%, was satisfactory. © 1992 Taylor and Francis Group, LLC.