A highly sensitive method for Cyanide determination in aqueous samples by liquid chromatography positive electrospray ionization tandem mass spectrometry after chemical derivatization with CAX B.

Moran Madmon, Analytical Chemistry, IIBR, Ness Ziona, Israel (moranm@iibr.gov.il)
Avital Shifrovich, Analytical Chemistry, Iibr, Ness Ziona, Israel
Avi Weissberg, Analytical Chemistry, Iibr, Ness Ziona, Israel

Cyanide (CN) is known as one of the most rapidly acting and powerful poisons. We have developed a highly sensitive method for the determination of cyanide in aqueous media. The method incorporates one step derivatization of cyanide with N-(2-(Bromomethyl)benzyl)-N,N-diethylethanaminium bromide (CAX B). The reaction was carried out for 15 min at 50^OC and the CN derivative was directly analyzed by liquid chromatography electrospray ionization mass spectrometry in the positive ion mode, without any purification. The reaction time, base addition, temperature and derivatizing agent amount were optimized. The optimal procedure included addition of CAX B to a basified water sample (pH=9) in an injection vail and stirring for 15 min at 50^OC, prior to LC-ESI(+)-MS/MS analysis. The CN derivative was stable for at least 48 h and exhibited an informative ESI-MS/MS spectrum characterized by product ions at m/z 130, 103, 100 and 86 from the MH⁺ ion m/z 231. The method linear dynamic range is 0.1-50 ng/mL with a limit of detection (LOD) and limit of quantification (LOQ) of 20 and 100 pg/mL, respectively. The developed method is fast, simple, sensitive and informative. It can be applied to determine cyanide in trace amounts in source drinking water for forensic investigations and for public safety purposes.