Multi-response optimization of magnetic solid phase extraction based on carbon coated Fe3O4 nanoparticles using desirability function approach for the determination of the organophosphorus pesticides in aquatic samples by HPLC-UV

The present study investigates the application of carbon coated Fe3O4 (Fe3O4/C) magnetic nanoparticles as an adsorbent for magnetic solid phase extraction (MSPE) of trace amounts of organophosphorus pesticides (OPPs) from environmental water samples and their determination using high performance liquid chromatography with ultraviolet detection (HPLC-UV). The Fe3O4/C magnetic nanoparticles were synthesized by a simple hydrothermal reaction and the resultant material was characterized by X-ray powder diffraction, field emission scanning electron microscopy and Fourier transform infrared. Central composite design combined with desirability function (DF) was applied to find the experimental conditions providing the highest global extraction efficiency. These conditions were found in correspondence with a solution pH of 9.16, 97.4 mg Fe3O4/C and 10 mmol L-1 NaCl added to samples. Under the optimal conditions, the proposed method was evaluated, and applied to the analysis of OPPs in water samples. The results demonstrated that our proposed method had wide dynamic linear range (0.05-400 ng mL(-1)) with a good linearity (R-2 > 0.9949) and low detection limits (4.3-47.4 pg mL(-1)). High enrichment factors were achieved ranging from 330-1200. The established MSPE-HPLC-UV method has been successfully applied for the determination of the OPPs in spiked water samples (well, tap, river and mineral). Satisfactory recovery results showed that the matrices under consideration do not significantly affect the extraction process. (C) 2012 Elsevier B.V. All rights reserved.