Synthesis of PAN/CZMA-LDH Electrospun Nanofibers as a New Sorbent in the Microextraction on Screw of Organophosphorus Pesticides from Vegetable Samples

Organophosphorus pesticides (OPPs) are widely used to control the yield of agricultural products. But OPPs are highly toxic even at low concentrations, and can be transferred to human food chain through different ways. Therefore, the detection and determination of OPPs is fundamentally essential [۱]. Due to the low concentration of OPPs in the real samples and the matrix complexity of the real samples, it is very challenging to measure OPPs accurately and precisely. Employing an extraction technique may be useful for overcoming the mentioned challenges. Solid-phase microextraction (SPME) is a class of the sample preparation methods with significant advantages, such as, the reduction or absence of organic solvents, and enhanced sensitivity due to concentration of analytes in a small extraction phase [۲]. Microextraction on screw (MES) is one of the SPME techniques that is able to eliminate the disadvantages of conventional methods, in this method a screw was utilized as a substrate and its surface was coated with the desired sorbent. Passing the sample solution through the spiral path of the grooves on the screw surface increases the contact surface between the sample solution and the sorbent, thus the extraction efficiency increases [۳]. This research is an attempt to expand the recently reported MES method. For this purpose polyacrylonitrile/calcined ZnMgAl-LDH nanofiber was fabricated with the aid of the electrospinning technique on screw surface and applied for extraction of OPPs from agricultural samples. Separation and determination of OPPs was performed by GC-MS spectrometry analysis. Characterization of the fabricated nanofiber was carried out utilizing FTIR spectroscopy, FESEM and EDX. Effective parameters on extraction efficiency of the analytes including sample pH, ionic strength, sample flow rate and number of cycles, type, volume and flow rate of desorption solvent were optimized using one variable at a time method. Under the optimized conditions, the limit of detection were ۰.۰۳ and ۰.۰۷ μg L-۱ for diazinon and chlorpyrifos, respectively. This method showed good linearity in the range of ۰.۱۰-۱۰۰۰.۰۰ μg L-۱ for diazinon and ۰.۲۵-۱۰۰۰.۰۰ μg L-۱ for chlorpyrifos with R۲ > ۰.۹۹۶. The intra- and inter-day precisions (RSD%, n = ۳) were ≤ ۶.۴% and ≤ ۷.۷%, respectively. Also, RSD% values less than ۱۱.۱% were obtained for screw to screw reproducibility. To investigate the extraction efficiency,PAN/CZMA-LDH was employed to analyze various vegetable samples, including cabbage, potato, tomato, cucumber and beetroot where it led good recoveries ranged between ۶۵% and ۸۴%.