Separation of thiol and cyanide hydrolysis products of chemical warfare agents by capillary electrophoresis

The fluorescence derivatizing agent, o-phthalaldehyde (OPA), has been applied to the separation and detection of cyanide and several structurally similar thiols by capillary electrophoresis (CE)-laser induced fluorescence (LIF). Of particular interest to this investigation was the separation of 2-dimethylaminoethanethiol, 2-diethyl-aminoethanethiol, and cyanide, each of which are hydrolysis products or hydrolysis product simulants of the chemical warfare (CW) agents O-ethyl S-2-diisopropylaminoethyl methylphosphonothiolate (VX), O-isobutyl S-2-diethylaminoethyl methylphosphonothiolate (R-VX), and tabun (GA). Other structurally similar thiols simultaneously resolved by this method include 1-pentanethiol and 2-mercaptoethanol. Instrumental parameters were probed and optimum values for capillary length (50 cm) and inner diameter (75 mum), injection time (30 s) and field strength (15 kv) were determined. Sample stacking methods enabled detection limits of 9.3 mug/L for cyanide, 1.8 mug/L for 2-diethylaminoethanethiol, 35 mug/L for 2-dimethylaminoethanethiol, 15 mug/L for 2-mercaptoethanol, and 89 mug/L for 1-pentanethiol. The linearity of the method was verified over an order of magnitude and the reproducibility was found to be 3.0%.