unambiguous identification of chemicals related to the chemical weapons convention (cwc) in environmental samples in the 50th international official opcw proficiency test

Abstract: the opcw (organization for the prohibition of chemical weapons) has a worldwide network of designated laboratories for environmental and biomedical sample analysis related to chemical weapon convention (cwc). these laboratories are required to have international accreditation like iso/iec 17025 and participate in annual proficiency tests to keep their designation [1]. the samples are collected by the opcw inspection team according to the special scenario and analyzed at the opcw’s designated laboratories in each proficiency test. currently (2022), opcw has 24 laboratories designated for environmental samples [2]. the 50th official opcw proficiency test was conducted by opcw in october and november of 2021, in which 6 liquid samples including 3 solvent waste samples and 3 aqueous waste samples were sent by opcw in the volume of about 5 and 7 ml, respectively. dcrl received the samples on november 14, 2021. the samples were analyzed for reporting scheduled chemicals related to cwc and/or their degradation/reaction products during 15 days. liquid-liquid and solid-phase extractions, direct evaporation, different clean-up and various derivatization procedures were used for sample preparation. for unambiguous identification of chemicals, different analytical techniques such as gc-ms (ei), gc-ms (ci), gc-fpd and lc-ms/ms (esi) were utilized. according to the analysis rules of opcw, the identification is considered unambiguous if two different spectrometric techniques giving consistent results confirm the presence of the same chemical [3]. in order to support the identification of the reported test chemicals, it is essential to search the measured data against spectral libraries such as the national institute of standards and technology (nist) ms library or ocad (opcw central analytical database). in most cases, the identification is verified by comparison to a reference chemical analyzed under identical conditions [1, 3]. in the 50th proficiency test, six spiking chemicals related to cwc were unambiguously identified. all of them were compared with reference standard chemicals which were synthesized at dcrl during the test period. sufficient data were presented to support the identification of spiking chemicals in accordance with opcw rules [3]. according to final report of opcw, dcrl could acquire “a” (maximum) score in the 50th official opcw proficiency test and keep its designation.