Knaack_2012_Anal.Chem_84_9470

An automated high-throughput immunomagnetic separation (IMS) method for diagnosing exposure to the organophosphorus nerve agents (OPNAs) sarin (GB), cyclohexylsarin (GF), VX, and Russian VX (RVX) was developed to increase sample processing capacity for emergency response applications. Diagnosis of exposure to OPNAs was based on the formation of OPNA adducts to butyrylcholinesterase (BCHE). Data reported with this method represent a ratio of the agent-specific BCHE adduct concentration, relative to the total BCHE peptide concentration that provides a nonactivity measurement expressed as percent adducted. All magnetic bead transfer steps and washes were performed using instrumentation in a 96-well format allowing for simultaneous extraction of 86 clinical samples plus reference materials. Automating extractions increased sample throughput 50-fold, as compared to a previously reported manual method. The limits of detection, determined using synthetic peptides, were 1 ng/mL for unadducted BCHE and GB-, GF-, VX-, and RVX-adducted BCHE. The automated method was characterized using unexposed serum and serum pools exposed to GB, GF, VX, or RVX. Variation for the measurement of percent adducted was <12% for all characterized quality control serum pools. Twenty-six (26) serum samples from individuals asymptomatic for cholinesterase inhibitor exposure were analyzed using this method, and no background levels of OPNA exposure were observed. Unexposed BCHE serum concentrations measured using this method ranged from 2.8 mug/mL to 10.6 mug/mL, with an average concentration of 6.4 mug/mL.