Effects of common metal ions on the determination of anions by suppressed ion chromatography

Abstract

The effects of common metal ions (Na +, K +, Ca 2+, Mg 2+, Al 3+ and Fe 3+) on the determination of nitrate, phosphate and sulfate by suppressed ion chromatography were investigated. The responses of nitrate within 1–10 mg/l were not affected in the presence of six metal ions at 10 mg/l. The peak areas of 1.0 mg/l sulfate increased significantly at 10 mg/l Fe 3+ or Al 3+ up to 51.34 and 48.37%, respectively. In the presence of 10 mg/l Fe 3+, the peak area of 1 mg/l and 10 mg/l phosphates decreased by 91.44 and 33.71%, respectively. At 10 mg/l Al 3+ the peak areas of phosphate also increased slightly. The adverse effect of Fe 3+ on the determination of phosphate could be overcome effectively by reducing the pH of the samples. The method to overcome the adverse effect was studied.