[Determination of trace chloride in sodium sulfate of analytical reagent-grade by valve-switching ion chromatography]

A valve-switching ion chromatography system was developed for the determination of trace chloride in sodium sulfate using a single pump, a suppressor, two valves and three columns. Using this technique, the trace chloride was eluted from the concentrator column (IonPac TAC-ULP1, 23 mm x 5 mm) to the analytical column (IonPac AS18, 250 mm x 4 mm), and the sulfate flowed to the waste. Under the optimized separation conditions, the method showed good linearity (r2 > 0.999) in the range of 0.03 - 1 mg/L and the average recoveries of chloride were 98.0% - 103.0% with the relative standard deviation less than 2%. The limit of detection was 0.01 mg/L (S/N = 3). The results demonstrated that this system has the advantages of high sensitivity, facile automation and simple sample pretreatment, which might be a promising approach for the determination of trace chloride in high-purity reagents.