In this work, the simultaneous separation of a group of 12 pesticides (carbaryl, fensulfothion, mecoprop, fenamiphos, haloxyfop, diclofop, fipronil, profenofos, fonofos, disulfoton, nitrofen, and terbufos) by nano-liquid chromatography with UV detection is described. For the analyses, a 100 μm internal diameter capillary column packed with silica modified with phenyl groups was used. Experimental parameters, including the use of a trapping column for increasing the sensitivity, were optimized and validated. A preliminary study of the applicability of a rapid and practical dispersive solid-phase extraction (DSPE) procedure was developed for the extraction of some of these pesticides (carbaryl, fensulfothion, fenamiphos, fipronil, profenofos, fonofos, disulfoton, nitrofen, and terbufos) from Milli-Q water samples using multi-walled carbon nanotubes (MWCNTs). The method was validated through a recovery study at three different levels of concentration, obtaining limits of detection in the range 0.016–0.067 μg/L (below European Union maximum residue limits) for the majority of the pesticides. In this work, MWCNTs were reused up to five times, representing an important reduction of the waste of stationary phase. Furthermore, DSPE permitted a clear diminution of the total sample treatment time with respect to conventional SPE.
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M.A.R. wishes to thank the Spanish Ministry of Education for the FPU grant. J.H.B. wishes to thank the Spanish Ministry of Science and Innovation for the Ramón y Cajal contract at the University of La Laguna. M.A.R. would also like to thank Dr. S. Fanali for his helpful suggestions, as well as Dr. Z. Aturki for her help and support during the stay at the Institute of Chemical Methodologies of the CNR. Authors acknowledge Dr. M.A. Rodríguez-Delgado for his valuable comments and suggestions. This work has been supported by the Spanish Ministry of Science and Innovation (project AGL2009-07884/ALI).
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