Determination of perchlorate in nature water by ion chromatography with large volume injection

The method for trace perchlorate analysis in environmental water was set up with large volume (500 mu L) injection ion chromatography and conductivity detection. Perchlorate was separated with high capacity and hydroxide selective column (lonPac AS20) using 35 mmol/L KOH eluent at the flow rate of 0.25 mL/min. The eluent was generated on-line from EGC. The column has unique substrate coating of aliphatic backbone which makes the retention time of 4-chlorobenzene sulphonate ahead of perchlorate thus eliminating its interference with perchlorate. The detection limit of perchlorate was as low as 0.5 mu g/L. A linear calibration was obtained over the range of 1 to 1000 mu g/L with a correlation coeffient of 0.9991. The method was applied to the detection of perchlorate in Beijing's tap water and snow water. The recoveries of spiked standard were in the range of 87% - 114%. RSD of the peak area for the nine successive injections of 1 mu g/L perchlorate solution was 6. 9%.