Determination Of Pyrethroid Pesticides Research Articles

An enhanced dispersive liquid–liquid microextraction method based on solidification of floating organic drops for the determination of pyrethroid pesticides in tea infusions

A novel enhanced dispersive liquid–liquid microextraction method based on solidified floating organic solvents containing [P4,4,4,12][PF6] and a hydrophobic solvent mixture for the determination of four pyrethroid insecticides in tea infusions.

Effervescent tablet-assisted switchable hydrophilicity solvent-based on-site dispersive liquid-liquid microextraction coupled with gas chromatography for the determination of pyrethroid pesticides in environmental waters

A novel effervescent tablet-assisted switchable hydrophilicity solvent-based on-site dispersive liquid-liquid microextraction coupled with gas chromatography detection has been developed to determine five pyrethroid insecticides in environmental water samples. In this method, effervescent tablets contain effervescent precursors and extractants, which play a dual role of dispersion and extraction. After effervescence reaction, the formation of extractant and the extraction of analytes were accomplished simultaneously. Phase separation were carried by filtration using homemade filter column, which of filter is oil-absorbing cotton polypropylene. After phase separation, the extractant phase were obtained by elution. No electric instrument was required in sample pre-treatment step in the developed method. Experimental conditions affecting the extraction efficiencies have been optimized, such as type and amount of extractant, type of effervescent tablets, etc. Under the optimized conditions, the linearity was 5-500μg L-1, with coefficients greater than 0.9990. The limit of detection and the limit of quantitation were in the range of 0.22-1.88μg L-1 and 0.75-6.25μg L-1. The relative standard deviations ranged from 0.8% to 6.1%. The enrichment factors were in the range of 65-108. This method was successfully applied to the on-site processing of tap, reservoir and river water.

Determination of pyrethroid pesticides in tea by accelerated solvent extraction and ultra-performance liquid chromatography-tandem mass spectrometry

A method was developed for the determination of pyrethroid pesticides in tea by accelerated solvent extraction (ASE) combined with ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The target compounds were extracted from tea using n-hexane and acetone (2:1, v/v) for 5 min at 10.34 MPa and 80℃ via a single cycle of accelerated solvent extraction. The extract was purified by GCB/NH2 and Florisil columns, analyzed by UPLC-MS/MS in positive electrospray ionization (ESI+) and multiple reaction monitoring (MRM) modes, and quantified by the external standard method. Regression analysis revealed that the linear relationships between mass concentration and peak area are significant for the 10 pyrethroid pesticides, and the correlation coefficients (r) are all not less than 0.9995. The limits of detection (LOD) of the 10 pyrethroid pesticides ranged from 0.5 μg/kg to 5.0 μg/kg and the limits of quantification (LOQ) ranged from 1.6 μg/kg to 16.6 μg/kg. The recoveries of all the pesticides ranged from 68.7% to 103.8% at the spiked levels of LOQ, 0.4 mg/kg and maximum residue limit (MRL) (added 1 mg/kg without MRL) with RSDs ranging from 0.8% to 13.2% (n=7). The proposed method is simple, rapid, sensitive, and accurate, and could be effective for trace analysis of pyrethroid pesticides in tea.

Determination of pyrethroid pesticides in tea by series two-solid phase extraction-columns cleanup and gas chromatography-tandem mass spectrometry

A rapid determination method of three pyrethroid pesticides (cyfluthrin, cypermethrin and fenvalerate) in tea was developed by series two-solid phase extraction-column cleanup and external standard method coupled with gas chromatography-tandem mass spectrometry (GC-MS/MS) in 30 min. The pesticide residues in tea were extracted with acetonitrile, and cleaned up by Carb/NH2 and SLH solid-phase extraction columns. After filtration, the target compounds were analyzed by GC-MS and quantified by the external standard method. Under the optimized conditions, good linear ranges of 0.05-2.00 mg/kg were obtained. The limits of detection varied from 0.3 to 1.0 μ g/kg. The linear correlation coefficients were greater than 0.999. At three spiked levels (0.10, 0.50 and 2.00 mg/L), the average recoveries were determined between 80.6% and 116.3% in the four matrices. The inter-day relative standard deviations were between 1.3%-12.6%, and the intra-day relative standard deviations were between 2.7% and 12.1%. This method is simple, fast, and has a good reproducibility, which can meet the requirements of the rapid detection of pyrethroid pesticides in tea.

Determination of Pyrethroid Pesticides in Tomato Using Ionic Liquid-Based Dispersive Liquid-Liquid Microextraction

A sensitive determination method was developed for the analysis of pyrethroid pesticide residues in tomato samples using ionic liquid-based dispersive liquid-liquid microextraction. A hydrophobic ionic liquid (1-butyl-3-methylimidazolium hexafluorophosphate) and acetonitrile were used as the extraction solvent and dispersive solvent, respectively. The following experimental parameters affecting the extraction efficiency were examined: types of extraction solvent and volume of extraction solvent, types of dispersive solvent and volume of dispersive solvent and pH and ion strength of the sample solution. Under the optimum conditions, the extraction recoveries ranged from 83.9 to 96.7%. Moreover, the enrichment factors for esbiothrin, fenpropathrin and cyhalothrin were 42, 48 and 45, respectively. The calibration curves were linear with correlation coefficients ranging from 0.9997 to 0.9999 at concentrations of 0.05-1.5 µg/kg. The relative standard deviation (n = 5) was 1.7-4.5%. The limits of detection for esbiothrin, fenpropathrin and cyhalothrin were 8.1, 9.9 and 14.3 µg/kg, respectively.

Determination of Pyrethroid Pesticides in Environmental Waters Based on Magnetic Titanium Dioxide Nanoparticles Extraction Followed by HPLC Analysis

A simple and fast method based on magnetic separation for extraction of pyrethroid pesticides including beta-cyfluthrin, cyhalothrin and cyphenothrin from environmental water samples has been established. Magnetic titanium dioxide was used as sorbent, which was synthesized by coating TiO2 on Fe3O4 in liquid-state co-precipitation method. The sorbent has been characterized by scanning electron microscopy and Fourier-transform infrared spectrometry, and the magnetic properties were investigated with physical property measurement system. Various parameters affecting the extraction efficiency were evaluated to achieve optimal condition and decrease ambiguous interactions. The analytes desorbed from the sorbent were detected by high performance liquid chromatography. Under the optimal condition, the linearity of the method is in the range of 25–2,500 ng L−1. The detection limits and quantification limits of pyrethroid pesticides are in the range of 2.8–6.1 ng L−1 and 9.3–20.3 ng L−1, respectively. The relative standard deviations of intra- and inter-day tests ranging from 2.5 to 7.2 % and from 3.6 to 9.1 % were obtained. In all three spiked levels (25, 250 and 2,500 ng L−1), the recoveries of pyrethroid pesticides were in the range of 84.5–94.1 %. The proposed method was successfully applied to determine pyrethroids in three water samples. Cyphenothrin was found in one river water near farmlands, and its concentration was 52 ng L−1.

Determination of pyrethroid pesticides in environmental samples using ionic liquid dispersive liquid-liquid microextraction

Dispersive liquid-liquid microextraction (DLLME) using ionic liquid (IL) as extraction solvent was developed as a new approach for the determination of four pyrethroid pesticides in environmental water and soil samples. High-performance liquid chromatography with ultraviolet detection (HPLC-UV) was employed on chromatographic analysis. The method is rapid, easy to operate and enviromentally-friendly. The highly toxic chlorinated solvent was replaced by the IL 1-hexyl-3-methylimidazolium hexafluorophosphate ([C6MIM][PF6]), in which high extraction recovery and enrichment factors were obtained. The effects of IL volume, type and volume of disperser solvent, salt addition, pH and extraction time were investigated and optimized. Under optimum conditions, the method showed good linear response with correlation coefficient (R²) values in the range of 0.9943 to 0.9986. Relative standard deviation (RSD) varied from 3.9 to 10.1%. Enrichment factor, limit of detection and recovery ranged from 260 to 319, 0.94 to 1.97 µg L-1 and 89 to 98%, respectively. For real water samples, RSD ranged from 3.8 to 10.8%, and recovery from 83 to 99%. For soil sample analysis, RSD and recovery ranged from 3.7 to 8.9% and 88 to 98, respectively.

Establishment of trace determination method of pyrethroid pesticides with TiO2 nanotube array micro-solid phase equilibrium extraction combined with GC-ECD

This paper described a new method for the enrichment and determination of pyrethroid pesticides from environmental water samples with ordered TiO(2) nanotube array micro-solid phase equilibrium extraction (μ-SPEE) prior to gas chromatography (GC) with electron capture detection (ECD). Several factors such as the anodization voltage, the kind of organic solvents, sample pH, equilibrium extraction time, desorption time and salting-out effect were optimized. Under the optimal conditions, ordered TiO(2) nanotube arrays demonstrated excellent merits on the preconcentration of pyrethroid pesticides and good detection limits were achieved as 0.018, 0.020, 0.031, 0.041, and 0.070 μg L(-1) for bifenthrin, fenpropathrin, cyhalothrin, fenvalerate, and deltamethrin, respectively. Four real water samples were used to validate the proposed method and the spiked recoveries were over the range of 81.9-110.6%. Compared to conventional solid phase extraction (SPE), the present method showed better recoveries and good reproducibility. These results showed that this μ-SPEE technique could be an important alternative to multistep SPE for the extraction and determination of such analytes in complex samples and become a useful tool in monitoring such analytes in the environment.

Design of a compressed air modulator to be used in comprehensive multidimensional gas chromatography and its application in the determination of pesticide residues in grapes

In this study, a new modulator that is simple, robust and presents low operation costs, was developed. This modulator uses compressed air to cool two small portions in the first centimeters of the second chromatographic column of a comprehensive multidimensional gas chromatography (GC × GC) system. The results show a variation in the peak area less than 3 and 5% to alkanes and pesticides, respectively. The standard deviations for the retention times in the first and second dimension are around 0.05 min and 0.05 s for all the compounds. The system was optimized with n-alkanes. The GC × GC system proposed was applied in the determination of pyrethroid pesticides (bifenthrin, cypermethrin, deltamethrin, fenvalerate, esfenvalerate, cis- and trans-permethrin) in grape samples. Samples were extracted by the mini-Luke modified method and pesticides were quantified by comprehensive multidimensional gas chromatography with micro electron-capture detection (μECD). The values of method limit of quantification (LOQ) were 0.01–0.02 mg kg −1 for all studied pyrethroid and the values of recovery were between 94.3 and 115.2%, with good precision (RSD < 18.4%), demonstrating that the performance of the total method consisting of a modified Luke extraction method and determination by GC × GC-μECD are satisfactory. This study also showed that the system using a modulator with a double jet of compressed air has the potential for application in the analysis of a wider range of pesticide residues in other commodities since it provides low values of LOQ with acceptable accuracy and precision.