Determination of sulfur in coal by solid sampling graphite furnace high-resolution molecular absorption spectrometry

Abstract

An analytical procedure for quantitative analysis of sulfur in coal by direct solid sampling graphite furnace high-resolution continuum source molecular absorption spectrometry (HR-CS GF MAS) is described, which is based on the molecular absorption of tin sulfide. The heating program is optimized, and a series of chemical modifiers (Ir, Mg, Pd, Ru, W, Zr) are tested. All measurements are accomplished with an Ir coated platform and Pd as modifier, because the best results are achieved.Accurate results are obtained using the central SnS line of the band found at 271.578nm with precision values between 1 and 6%. A limit of detection of 10ngS absolute is achieved. Furthermore, the trueness of the procedure is verified by analysis of certified reference materials. Several coal samples with a concentration range from 0.8 to 21.7mgg−1S and three certified reference materials are analyzed. In all cases, simple calibration with aqueous standards is found to be possible and the sample throughput is 2–3 samples per hour (6 replicates per sample).