Derivatization Method of Free Cyanide Including Cyanogen Chloride for the Sensitive Analysis of Cyanide in Chlorinated Drinking Water by Liquid Chromatography-Tandem Mass Spectrometry

摘要

A novel derivatization method of free cyanide (HCN + CN) including cyanogen chloride in chlorinated drinking water was developed with d-cysteine and hypochlorite. The optimum conditions (0.5 mM d-cysteine, 0.5 mM hypochlorite, pH 4.5, and a reaction time of 10 min at room temperature) were established by the variation of parameters. Cyanide (C13N15) was chosen as an internal standard. The formed beta-thiocyanoalanine was directly injected into a liquid chromatography-tandem mass spectrometer without any additional extraction or purification procedures. Under the established conditions, the limits of detection and the limits of quantification were 0.07 and 0.2 mu g/L, respectively, and the interday relative standard deviation was less than 4% at concentrations of 4.0, 20.0, and 100.0 mu g/L. The method was successfully applied to determine CN in chlorinated water samples. The detected concentration range and detection frequency of CN were 0.208.42 mu g/L (14/24) in source drinking water and 0.211.03 mu g/L (18/24) in chlorinated drinking water.