A novel sorbent based on a UVM-7 mesoporous silica doped with Ti has been synthesized and used for solid-phase extraction of several organophosphorus pesticides in environmental water samples followed by gas chromatography coupled to a nitrogen-phosphorus selective detector. Thus, mesoporous silica materials doped with Ti and Fe as well as immobilized cyclodextrin silica-based supports were prepared and morphologically characterized by several techniques such as transmission electronic microscopy, nitrogen adsorption-desorption and X-ray diffraction. These sorbents were comparatively evaluated, and Ti25-UVM-7 material was selected as the best solid phase. After optimization of extraction parameters such as amount of solid-phase, type and volume of eluent, pH and ionic strength and breakthrough volume, recoveries between 81% and 104.5% were achieved, with RSD values below 7.8% and 12% for intra-day and inter-day repeatability respectively. Moreover, limits of quantification in the range 0.5-4.4 μg L-1 were achieved for all target compounds using mass spectrometry detector. In addition, the developed method was applied for analysis of real water samples and it was validated with commercial C18 cartridges. Matrix effect was demonstrated in complex environmental matrices and the good reusability of synthesized material was also proved.
Keywords: Gas chromatography; Mesoporous silica; Organophosphorus pesticides; Preconcentration; Solid-phase extraction; Water samples.
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