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Extraction of degradation products of chemical warfare agents: study of the titania dioxyde phase and of the hollow fiber liquid-phase microextraction
The goal of this work was to develop a sample treatment method before the liquid chromatography-mass spectrometry (LC-MS) analysis of degradation products of chemical warfare agents contained in aqueous samples. After developing a LC-MS method adapted to the alkyl methylphosphonic acids (AMPA) and the methylphosophonic acid (MPA), their retention on a titania dioxyde solid-phase was studied for their extraction and concentration from water samples. The obtained results being not satisfying an emerging technique was evaluated: the hollow fiber liquid-phase microextraction (HF-LPME). First, the HF-LPME was carried out in a two-phase mode that is more suitable before the gas chromatography analysis of the derivatized analytes. But the analysis method of choice being LC-MS for non-derivatized compounds, HF-LPME in a three phase mode was studied more in detail. The optimization of numerous parameters allows obtaining very high enrichment factors for the extraction of AMPAs from river water, without matrix effects, and from urine. But the extraction of the MPA was limited because of its high polarity. Therefore, a new transfer mode of the compounds was considered: electromigration (EME). High enrichment factors were obtained by HF-EME in pure water samples but its application to real matrices suffers from matrix effect. The use of an electrical field made the extraction of the AMPAs from high ion content samples (river water and urine) difficult. But, the HF-EME has provided very good results for the MPA that can not be extracted with conventional methods.