Abstract
The study was mainly to establish a simple purge-and-trap pretreatment combining with Ion Chromatography (IC) system for quantitative analysis of trace ammonium ion in the presence of high concentration of sodium ion. The new method has been applied for the analysis of ammonia from seawaters and the photolysis of copper(II) – amino acid complexes. Although IC is a quick and effective technique utilized to determine inorganic cations and ammonium, it is extremely difficult to analyze samples of very dissimilar concentration ratios of sodium-to-ammonium, such as seawater. Different from other cations with only one species form, ammonium could be deprotonated to ammonia under high pH. Then ammonia exchange between water and gas could be occurred by purging and trapping. The collected ammonium is further analyzed by IC. The pretreatment system is not only a preconcentration technique but also is highly effective in removing matrix interferences. The present approach provides low limits of detection and keeps column performance longer. The formation rate ratios of copper(I) to ammonium ion in aqueous solution without oxygen under monochromatic radiation at 313 nm were around 2 to 4, probably relating to the different side chains of amino acids as the ligands.