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The use of capillary electrophoresis (CE) has been restricted to applications having high sample concentrations because of its low sensitivity caused by small injection volumes and, when ultraviolet (UV) detection is used, the short optical path length. Sensitivity in CE can be improved by using more sensitive detection systems, or by preconcentration techniques which are based on chromatographic and/or electrophoretic principles. One of the promising strategies to improve sensitivity is solid phase extraction (SPE). Solid Phase Extraction utilizes high sample volumes and a variety of complex matrixes to facilitate trace detection. To increase the specificity of the SPE a selective solid phase must be chosen. Immunosorbents, which are a combination of an antibody and a solid support, have proven to be an excellent option because of high selectivity of the antibody. This thesis is an exploratory study of the application of immunosorbent-SPE combined with CE for trace concentration of benzodiazepines. This research describes the immobilization and performance evaluation of an immunosorbent prepared by immobilizing a benzodiazepine-specific antibody on aminopropyl silica. The binding capacity of the immunosorbent, measured as µg of benzodiazepine/ gram of immunosorbent, was 39 ± 10. The long term stability of the prepared immunosorbent has been improved by capping the remaining aminopropyl groups by reaction with acetic anhydride. The capped immunosorbent retained its binding capacity after several uses.

L'objectif de ce travail était de développer une méthode de traitement de l'échantillon permettant l'analyse par LC-MS2 d'adduits formés entre des composés neurotoxiques organophosphorés (OPNA) et la butyrylcholinesterase, protéine plasmatique. En vue d'une automatisation totale du processus analytique, une étape d'immunoextraction a été couplée à un réacteur de digestion enzymatique (IMER), suivie d'une analyse par microLC-MS2 afin de détecter le peptide adduit par l'OPNA. Tout d'abord, la synthèse d'IMER de pepsine a été optimisée. L'IMER le plus performant a été appliqué à la digestion de la BuChE afin d'analyser le peptide biomarqueur d'intoxication, par nanoLC-MS2. Un IMER de pepsine, de dimensions supérieures a pu être rapidement intégré à un système d'analyse microLC-MS2, permettant la digestion de la BuChE et l'analyse en ligne du peptide cible. Dans un second temps, une méthode d'extraction sélective a été développée par immobilisation de différents anticorps anti-BuChE sur un support solide appelé immunoadsorbant. Le protocole d'immunoextraction a été mis au point, puis les immunoadsorbants ont été caractérisés en termes de sélectivité et de rendement d'extraction avant d'envisager son couplage au digesteur enzymatique. La faisabilité du couplage a pu être clairement démontrée et ce dispositif automatisable a été appliqué à l'analyse de la BuChE de plasma humain, dopé par des OPNA. Cela a permis la détection rapide et sensible des adduits OPNA-BuChE, à partir de très faibles quantités de plasma. / The objective of this work was to develop a sample treatment method for the LC-MS2 analysis of adducts formed between organophosphorus nerve agent (OPNA) and butyrylcholinesterase, a plasmatic protein. In order to fully automate the analytical process, an immunoextraction step was coupled to an enzymatic digestion reactor (IMER), followed by microLC-MS2 analysis to detect the OPNA-peptide adduct. First, the synthesis of pepsin-based IMER was optimized. The most powerful pepsin-based IMER was applied to the digestion of HuBuChE to generate the peptide used as biomarker of OPNA intoxication that was further analyzed by nanoLC-MS2. This pepsin-based IMER was then integrated into a microLC-MS2 analytical system, allowing the on-line digestion of HuBuChE and the analysis of the target peptide. In a second step, a selective extraction method was developed by immobilizing anti-HuBuChE antibodies on a solid support, called immunosorbent. The immunoextraction protocol was developed and the immunosorbents were characterized in terms of selectivity and extraction yield before being coupled to the IMER. The feasibility of the coupling was clearly demonstrated and this automatable device was used for the analysis of HuBuChE from human plasma, spiked with OPNA. This allowed the fast and sensitive detection of OPNA-BuChE adducts in very small amounts of plasma.