Analysis of Ammonium in Seawater by Ion Chromatography With Single-Pump Column Switching

摘要

An ion chromatograph single-pump column-switching system was developed for the determination of ammonium in high salt matrices. The simple system included a pump, a suppressor, two valves, two columns, a single eluent, and a conductivity detector. Using this method, both online collection and matrix elimination were achieved. Ammonium was eluted from the acceptor loop to the analytical column circularly. Under the optimized separation conditions, the method showed good linearity (r = 0.9997) in the range of 0.05-2.0 mg/L and satisfactory repeatability (RSD > 4%, n = 6). The limit of detection was 4 mu g/L (S/N = 3) with 25 mu l injection. The utilization of the method was demonstrated by the analysis of seawater, with satisfactory spiked recoveries of ammonium between 98.8% and 108.7%. The result showed that the single-pump column-switching system was convenient and practical for the determination of low-level ammonium in high-salinity samples.