Mikrochim. Acta 106, 175-182 (1992) Mikrochimica Acta 9 by Springer-Verlag 1992 Printed in Austria High Speed Determination of Sulfate by Nonsuppressed Ion Chromatography Wolfgang Frenzel* and Annette Rauterberg Institut fiir Technischen Umweltschutz, Fachgebiet Luftreinhaltung, Technische Universit/it Berlin, Strage des 17. Juni 135, D-W-1000 Berlin 12, Federal Republic of Germany Abstract. Nonsuppressed ion chromatography using a short guard column is shown to offer a fast and reliable method for separation and determination of sulfate. By optimization of the eluent composition the retention time of sulfate is below 1 rain and sufficient resolution in the presence of excess of common anions is achieved. Calibration plots are linear in the range 0.5-200 mg/1 sulfate. The method has been applied to the analysis of airborne particulates, diesel soot and tap-water. Key words: ion chromatography, sulfate determination, high speed ion analysis. Sulfate frequently has to be determined in a wide variety of sample matrices in- cluding surface, ground and domestic waters, effluents, atmospheric deposits and soil. The determination of sulfate is presently accomplished utilizing gravimetric or turbidimetric determination of barium sulfate, titration procedures, various direct spectrophotometric methods and ion chromatograph [-1-4]. As far as gravimetric, turbidimetric, titrimetric and spectrophotometric methods are concerned limitations in the applicability exist due to the insufficient sensitivity, limited working range and interferences of bi- and trivalent cations. Moreover, the methods are laborious. These drawbacks, partially, can be overcome by application of automated flowthrough analysers based on air-segmentation or flow injection principle [-5-7]. Ion chromatography (IC) does not exhibit the limitations mentioned but is rather expensive and appears over-developed if only sulfate has to be determined. In addition, in conventional applications of IC the retention time of sulfate is about 10 min with corresponding low sample throughput. More recently, stationary phases have been developed which are capable to separate common anions in less than 5 min with high efficiencies. The capacity of these columns, however, is low and manufacturers usually recommend their use only for comparatively clean samples, e.g. tap- and groundwater. Moreover, application * To whom correspondence should be addressed