Dispersive micro-solid phase extraction with ionic liquid-modified silica for the determination of organophosphate pesticides in water by ultra performance liquid chromatography

In this article, the use of methylimidazolium-hexafluorophosphate functionalized silica is evaluated under a dispersive micro-solid phase extraction (D-mu SPE) approach for the extraction of organophosphate pesticides (OPs) from water samples. After its synthesis, the sorbent is chemically characterized playing special attention to the type of interaction that it can establish with the target analytes. Moreover, different dispersion approaches were evaluated in order to clarify the main parameters affecting the extraction. The ionic liquid-modified silica allows the isolation and preconcentration of the analytes (phosmet, parathion, triazophos and phoxim) with enrichment factors in the range from 74 (phoxim) to 111 (triazophos) in a simple procedure. The new extraction mode allows the determination of these compounds with limits of detection in the range from 0.3 mu g L-1 (for phosmet) to 0.6 mu g L-1 (for phoxim) with a relative standard deviation lower than 10.6% (for phoxim). The recovery study carried out in different water samples provided an average recovery of 94%. which demonstrated the applicability of the sorbent for the analytical problem selected in this article. (C)2012 Elsevier B.V. All rights reserved.