Selective Detection of Selenium in Water Utilizing Chemical Reaction Interface Mass Spectrometry†

Abstract

Gas chromatography/chemical reaction interface mass spectrometry (GC/CRIMS) is shown to be a successful selective method for the detection of selenium-containing compounds. Two reaction gases, sulfur dioxide (SO 2 ) and hydrogen chloride (HCl), were examined in order to optimize selectivity and sensitivity. A high degree of selectivity was obtained with SO 2 as a reaction gas; however, the detection limit of 50 SeO 3 + at m/z 128 (the most sensitive ion for the SO 2 -containing plasma) was only 3 ng μl -1 . HCl gas, which had been shown to be a good reaction gas for snufur-containing compounds, was also shown to be an excellent reaction gas for selenium-containing compounds. In the HCl-containing plasma, 80 SeCl + at m/z 115 was the most sensitive and selective ion for the detection of selenium-containing compounds. Selectivity was demonstrated by using mixtures of selenium-containing and non-selenium-containing compounds. The utility of GC/CRIMS as a method for the selective detection of selenium-containing compounds was demonstrated with a variety of selenium complexes that were formed by the addition of selective selenium complexing agents to selenium-containing water. The detection limit of selenium in water was ∼62 pg and the linear dynamic range spanned at least two orders of magnitude (620 pg pl -1 -308 ng μl -1 ).