Determination Of Some Pesticide Residues In Environmental Samples By Some Novel Adsorbents Coupled With High Performance Liquid Chromatography

Pollutants in environmental samples are generally present in low concentrations, andtherefore the separation and concentration of the target analyte, reducing or eliminating theinterferences originally present in the samples become one of the most critical steps in theentire analysis process. In this paper, magnetic solid phase extraction (MSPE) and the thinfilm microextraction (TFME) sample preparation technology combined with highperformance liquid chromatography (HPLC) were used to extract and determinate someorganic pollutants in the environmental water samples, fruit, vegetable and fruit juicesamples. Some carbamate pesticides, chlorophenol, phenylurea insecticides, and phenolicendocrine interferon were chosen as object analytes to investigate the performance of thedeveloped sample pretreatment methods and the following research works have beencarried out:1. In this paper, a novel graphene (G) grafted silica-coated Fe3O4nanocomposite wasfabricated by the chemical bonding of G onto the surface of silica-coated Fe3O4nanoparticles. Some carbamates (metolcarb, carbaryl, pirimicarb, and diethofencarb) incucumber and pear samples were enriched by this nanocomposite prior to theirdetermination by HPLC with UV detection. Experimental parameters that may affect theextraction efficiency were investigated. Under the optimum conditions, a linear responsewas achieved in the concentration range of0.5–100.0ng/g for metolcarb, carbaryl, anddiethofencarb, and1.0–100ng/g for pirimicarb with the correlation coefficients (r) rangingfrom0.9956to0.9984. The LOD (S/N=3) of the method were found to be in the rangefrom0.08to0.2ng/g. The RSDs were in the range from2.4to5.8%. The results indicatedthat the G grafted silica-coated Fe3O4nanocomposite was stable and efficient for magneticSPE and has a great application potential for the preconcentration of other organicpollutants from real samples.2. A novel magnetic microporous carbon nanocomposite was fabricated. Some CPs(2-CP,3-CP,2,3-DCP, and3,4-DCP) in environmental water samples were enriched by thismagnetic nanocomposite adsorbent prior to their determination by HPLC with UVdetection. Experimental parameters which may affect the extraction efficiency were researched. Under the optimum conditions, a good linear was obtained in the concentrationrange of1.0~100.0ng/mL for all the analytes with the correlation coefficients (r) rangingfrom0.9948to0.9976. The LODs (S/N=3) of the method were0.1ng/mL. The RSDswere lower than5.3%. The results indicated that the magnetic mesoporous carbonnanocomposite was stable and efficient for MSPE and has a great application potential forthe preconcentration of other organic pollutants from complex samples.3. Poly (vinylidene fluoride)(PVDF) has attracted enormous attention as a membranematerial with regard to its excellent properties in recent years. In this paper, a new samplepreparation technique, the PVDF membrane as the extraction phase has been applied to theextraction of four endocrine-disrupting compounds: Bisphenol A (BPA),4-t-octylphenol(4-t-OP), nonylphenol (NP), and4-nonylphenol (4-NP) from water samples for the firsttime, prior to their determination by high performance liquid chromatography–ultravioletdetection. Some important experimental parameters affecting the extraction efficiencywere optimized. Good linearity was observed over the concentration range of1.0–100.0ng/mL for BPA, and2.0–100ng/mL for4-t-OP, NP and4-NP with the correlationcoefficients (r) greater than0.9934. The limit of detection (S/N=3) of the method was0.2ng/mL for BPA, and0.4ng/mL for4-t-OP, NP and4-NP. The method is convenient, costeffective and can be a useful alternative approach for the extraction and determiantion ofthe endocrine-disrupting compounds in water samples.4. In this paper, a novel thin film microextraction (TFME) method based onpoly(vinylidene fluoride) membrane was developed for the extraction of benzoylureainsecticides (diflubenzuron, triflumuron, hexaflumuron and teflubenzuron) from watersamples followed by their determination with high performance liquidchromatography-diode array detection. The developed TFME method is simple, effective,lower cost and provides a good extraction efficiency. Several important parameters thataffect the extraction efficiencies were investigated and optimized. Under the optimumconditions, the method showed good linearity for all analytes over the studiedconcentration range with correlation coefficient (r) higher than0.9994. Based on S/N=3,the limits of detection of the method for these compounds were0.1ng/mL. Meanrecoveries ranged from92.7%to103.9%with relative standard deviations lower than6.2%(spiked level of10.0ng/mL).