Photometric and Ion Chromatographic Determination of Sulfate in Deoiling Agents with Elimination of Complex Organic Matrix Interference by Combined Use of Salting-out and Active Carbon Adsorption

In order to determine sulfate in deoiling agents by BaCrO4-photometry or ion chromatography, a simple and fast method for elimination of the complex organic matrix interference was proposed by the combined use of salting-out and active carbon adsorption. Optimum conditions for matrix separation were tested, including sample pretreatment methods, sort and amount of salts and active carbon used in the separation. It was found that effective separation was achieved by the combination of salting-out and active carbon adsorption. Optimum mass concentrations of salt (NaCl for photometry and NH4OAC for IC) and active carbon were found to be 60, 40 g·L-1 respectively. Contents of five samples of deoiling agents were determined by applying the proposed separation, and consistent results were obtained between photometric and IC methods.