MIL-101 (Cr) @ graphene oxide-reinforced hollow fiber solid-phase microextraction coupled with high-performance liquid chromatography to determine diazinon and chlorpyrifos in tomato, cucumber and agricultural water

Abstract

An effective, sensitive, relatively-fast and cost-effective method was developed to determine two types of selected organophosphorus pesticides (OPPs) including diazinon and chlorpyrifos in tomato, cucumber and agricultural water samples through applying MIL-101@ graphene oxide-reinforced hollow fiber solid-phase microextraction (MIL-101@GO–HF–SPME). The extracted analytes were desorbed via organic solvent and analyzed through high-performance liquid chromatography-ultraviolet detection (HPLC-UV) after extraction. MIL-101@ GO sorbent which was previously prepared and characterized was first dispersed in methanol by ultrasonication and then immobilized into the pores of a hollow fiber (HF). Several factors involved in MIL-101@GO–HF–SPME experiment such as desorption volume, ionic strength, desorption time, sample pH, extraction time and stirring rate were screened via Plackett–Burman design and then optimized through Box–Behnken design with the purpose of reaching the highest extraction efficiency. The above method showed a good linear range (1–500 μg L−1) with coefficient of determination higher than 0.9948, low limits of determination (LODs, 0.21 and 0.27 μg L−1), acceptable limits of quantifications (LOQs, 0.72 and 0.91 μg L−1), good enrichment factors (EFs, 49 and 41), acceptable absolute recoveries (AR%, 49 and 41%) and good spiking recoveries (88–104%) under the optimized condition at three different spiked levels for chlorpyrifos and diazinon, respectively. It is worth mentioning that due to the clean-up function of HF, there is no time-consuming sample pretreatment procedure (e.g. filtration or centrifugation) prior to the microextraction. Therefore, the presented method took advantage of both excellent adsorption performance of MIL-101@GO and the clean-up function of HF. The results confirmed that the presented method would be promising for the analysis of various types of these pesticides in environmental and vegetable samples.