Abstract: 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×5 mm) to the analytical column (IonPac AS18, 250 mm×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.

Key words: chloride, sodium sulfate of analytical reagent-grade, valve-switching, ion chromatography (IC)