Evaluation of the rotating disk sorptive extraction technique with polymeric sorbent for multiresidue determination of pesticides in water by ultra-high-performance liquid chromatography-tandem mass spectrometry

The use of pesticides has been associated with the increase of productivity of crops and control of vectors that cause diseases. However, excessive use of these compounds can cause human health and environmental problems, especially regarding to water resources. In this work, a method for multiresidue determination of 62 pesticides in surface water using the rotating disk sorptive extraction (RDSE) technique for sample preparation and ultra-high-performance liquid chromatography with tandem mass spectrometry (UHPLC-MS/IVIS) for analysis was optimized and validated. The parameters time and rotational disk velocity for the extraction step, types and amounts of sorbents, sample pH, ionic strength, time and velocity of the rotating disk in the desorption step, as well different desorption solvents were evaluated. The best results were obtained using 50 mL of sample, acidified at pH 2.0, and 2.5 g of sodium chloride. The selected velocity of rotation in the extraction step was 1600 rpm for 80 min. Inside the disk cavity, a small amount (20 mg) of the polymeric sorbent Oasis (R) HLB was used. The desorption step was performed immerging the disk in 3 mL of methanol and rotating the disk at 1600 rpm for 60 min. Procedural calibration curves showed linearity between 0.05 or 0.1-2 mu g L-1, with r(2) > 0.99 for all compounds. The method presented practical limit of quantification of 0.05 or 0.1 pg L-1 and suitable accuracy and precision, with recoveries from 70.1 to 119.9% and RSD <= 20% for the levels 0.05, 0.1, 0.5 and 2 mu g L-1. The validated method was applied to surface water samples from different river and residues of atrazine, azoxystrobin, clomazone, difenoconazole, epoxiconazole, propoxur, simazine and tebuconazole were found in the range of 0.06-0.35 mu gL(-1). The results indicate that the proposed method is suitable for the determination of pesticide residues in surface water, allowing an easy and simultaneously preparation of several samples with low material consumption. (C) 2017 Elsevier B.V. All rights reserved.