LAUSR

There have been no detailed investigations regarding solid-phase-extraction (SPE) optimization and screening for the degradation products of ethyl (1-(diethylamino)ethylidene)phosphoramidofluoridate (A234) in various environmental samples. Therefore, as a first step in the selective SPE of the degradation products of A234, we optimized the SPE adsorption and extraction parameters for the A234 degradation product ethylhydrogen (1-(diethylamino)ethylidene)phosphoramidate (cpd 1). Among various SPE cartridges, the Si cartridge (500 mg, 3 mL) selectively extracted cpd 1, using an elution volume of 4 mL of 25% H2O in acetonitrile, which eliminated most interference without cpd 1 loss during loading and washing. In addition, the sorbent capacity is also critical in the adsorption of cpd 1. The Si cartridge (500 mg, 3 mL) retained cpd 1 in the concentration range 1-10 µg/mL. The linearity of detector response of cpd 1 in deionized H2O was studied in range of 1.0 - 100 ng/mL, and showed good linearity with γ2 ranging from 0.9979 to 0.996. The limits of detection (LODs) for cpd 1 are 10 ng/mL in the product scan mode and 100 ng/mL in the full scan mode. Also, after we optimized the SPE method, we validated precision and accuracy of the Si-cartridge extraction method in real soil samples with diverse concentrations. The precision ranged from 2.5% to 5.3%. This newly developed SPE is applicable to the analysis of a degradation product of Novichok A234 in various environmental matrices, such as water, soil, and sand, in the OPCW proficiency test and unknown samples collected from suspected sites.