The application of ion chromatography (IC) with column-switching technique to simultaneous analysis of peroxydisulfate and conventional inorganic anions in a single running was described. With this method, conventional inorganic anions were separated by consecutive elution through both the guard column and separation column, but peroxydisulfate only passing through the guard column with good peak shape and short retention time, shown in Fig.1. A series of standard solutions consisting of target anions of various concentrations from 0.01 to 75 mg/L were analyzed, with correlation coefficient r≥0.9990. The limits of detection (LODs) were in the range of 0.49 to 9.84 µg/L, based on the signal-to-noise ratio of 3 (S/N=3) and a 25 µL injection volume. Relative standard deviations (RSDs) for retention time, peak area and peak height were all less than 1.77%. A spiking study was performed with satisfactory recoveries between 97.6% to 103.4% for all anions.The quantitative determination of peroxydisulfate and conventional inorganic anions in surface waters was accomplished within 18 min by this column-switching technique. 

Fig.1. Chromatogram of peroxydisulfate and conventional inorganic anions separated by the column-switching IC system. Peaks: (1) fluoride; (2) chloride; (3) nitrite; (4) nitrate; (5) sulfate; (6) phosphate; (7) peroxydisulfate.