Trace Determination of Nerve Agent Biomarkers in Human Urine Using a Combination of Ba/Ag/H and ZrO2 Solid-Phase Extraction Followed by LC-MS/MS Analysis

Merav Blanca, Analytical chemistry, IIBR, Ness Ziona, Israel (blanca.merav@gmail.com)
Avital Shifrovitch, Analytical Chemistry, Iibr, Ness Ziona, Israel
Tamar Shamai Yamin, Analytical Chemistry, Iibr, Ness Ziona, Israel
Avi Weissberg, Analytical Chemistry, Iibr, Ness Ziona, Israel

A Sensitive and Selective method for rapid determination of alkyl methylphosphonic acid (AMPAs) metabolites of five organophosphorous nerve agents (GB, GD, GF, VX, r-VX) in human urine is presented. The sample preparation involved loading the urine sample on a strong cation-exchange cartridge Ba/Ag/H connected to a selective reconstitute Zr0₂ solid-phase extraction. After washing the Zr0₂ cartridge with formic acid (pH 3), the AMPAs were eluted with 1% (v/v) ammonium hydroxide solution, and analyzed by liquid chromatography-mass spectrometry (LC-MS) in the negative ion mode. Critical extraction parameters such as nature and volume of washing and eluting solvents were investigated. The yields of AMPAs were in the range of 64 to 80% and detection limits were 50 pg/ml for EMPA, 20 pg/mI for IMPA, 5 pg/ml for CMPA, 5 pg/ml for PMPA and 30 pg/ml for IBMPA. The linearity showed a very good correlation in the concentration range of 0.1-100 ng/ml with r² ≥ 0.9993 for all metabolites. The procedure is simple and enables confirmation of nerve agent exposure within 20 min from sample receiving. This method is found to be the most sensitive, simple and cost effective for trace levels of AMPAs in urine samples.