Ion Chromatographic Method for the Determination of Selected Inorganic Anions and Organic Acids from Raw and Drinking Waters Using Suppressor Current Switching to Reduce the Background Noise

摘要

For the first time a direct ion chromatographic routine method was developed for the simultaneous determination of selected inorganic anions and organic acids from raw and drinking waters. The inorganic anions included the common inorganic anions (fluoride, chloride, nitrite, bromide, nitrate, sulfate, and phosphate) and also the iodide. Organic acids were lactate, acetate, propionate, formate, oxalate, and citrate. A hydrogen selective high capacity column AS11-HC was selected because it permits a large loop injection and provides excellent separation of oxalate from sulfate, even at concentration ratios as great as 1:10,000. The current to the ASRS suppressor running in the recycle mode was turned off at the beginning of the run and was turned on again after the elution of the nitrate peak, which dramatically reduced the baseline noise and, thus, enhanced sensitivity for 9 out of 14 anions. Detection limits (S/N = 6) were less than 1 μg/L for those ions eluting when there was no suppressor current and from 3 to 15 μg/L for the others.