Simultaneous determination of total nitrogen, phosphorus and sulphur by means of microwave digestion and ion chromatography

A method for the oxidation of nitrogen, phosphorus and sulphur to nitrate, phosphate and sulphate ions using 22% (v/v) hydrogen peroxide and closed-vessel microwave assisted digestion in two stages is described. Solutions of a variety of nitrogen-, phosphorus- and sulphur-containing compounds with formic acid added to prevent hydrolysis were used to test the efficiency of the procedure. The products of oxidation were determined by ion chromatography. Good recoveries of nitrogen, phosphorus and sulphur were obtained. The results for the NIST reference materials, oyster tissue and Buffalo River sediments agree well with the certified values. (C) 1999 Elsevier Science B.V. All rights reserved.