Determination of low-level anions in seawater by ion chromatography with cycling-column-switching

An ion chromatographic cycling-column-switching system was developed for the determination of low-level anions (fluoride, nitrite, nitrate, bromide, sulfate, and phosphate) in seawater using a single pump, a suppressor, two valves, and three columns. Using this technique, the low-level anions were eluted from the concentrator column to the analytical columns circularly, and the matrix flowed to the waste. Under the optimized separation conditions, the method showed good linearity in the range of 0.05–25.0 mg/L and satisfactory repeatability (RSD < 4%, n = 6). The limits of detection were in the range of 2–23 μg/L (S/N = 3). The result showed that the cycling-column-switching system was convenient and practical for the determination of trace anions in high-salinity samples.