LAUSR

Nerve agent metabolites (NAMs) derived from alkyl methyl phosphonic acids, such as ethyl methylphosphonic acid (EMPA), isopropyl methylphosphonic acid (IMPA), and pinacolyl methylphosphonic acid (PMPA), were extracted from human urine using diethyl ether as an extractant. After exchanging the diethyl ether solvent to acetonitrile, the analytes were derivatized with 2-(bromomethyl)naphthalene (BMN). The reaction products of the BMN and NAMs, i.e., MN-EMPA, MN-IMPA, and MN-PMPA, were separated by gas chromatography (GC) and measured by mass spectrometry (MS) using a femtosecond laser emitting at 267 nm as the ionization source for resonance-enhanced two-photon ionization (RE2PI). The limits of detection (LOD) were <1 ng/mL for these analytes. The use of BMN increased the volatility of the analytes for separation by GC and also increased the ionization efficiency via the RE2PI process as the result of presence of a naphthalene functional group. A two-dimensional GC-MS display can be used for comprehensive analysis of NAMs, by-products, and impurities in the sample. Then, this approach could be used to confirm the use of chemical weapons and for forensic identification.