Determination Of Pyrethroid Residues Research Articles

Determination of Pyrethroid Residues in Wooden Toys by Gas Chromatography and Gas Chromatography–Mass Spectrometry

A novel method for the determination of pyrethroid pesticide residues in wooden toys was developed. Wooden toy samples were extracted with petroleum ether−acetone (1 : 1, v/v), cleaned up on a florisil solid phase extraction cartridge and determined by gas chromatography equipped with electron capture detector (GC−ECD), followed by validation using gas chromatography−mass spectrometry (GC−MS) with negative chemical ionization. Calibration curves were linear in the range of 0.02–0.5 mg/kg with correlation coefficients exceeding 0.9975 for GC−ECD and GC−MS. At spiked concentrations of 0.1, 0.2 and 0.5 mg/kg, the average recoveries and relative standard deviations were 82–97% and 1.5–7.8%, respectively. The limit of quantification for each analyte was 0.1 mg/kg, which satisfied the current maximum residue limit permitted in wooden toys. Results also showed that the developed method could be successfully applied to determine permethrin, cypermethrin, cyfluthrin, deltamethrin residues in real wooden toy samples.

Determination of pyrethroid residues in herbal tea using temperature-controlled ionic liquid dispersive liquid-liquid microextraction by high performance liquid chromatography

A simple and effective method for determining five pyrethroid residues in herbal tea by ultrasound-enhanced temperature-controlled (UETC) ionic liquid dispersive liquid-liquid microextraction (IL-DLLME) coupled with high performance liquid chromatography-diode array detection (HPLC-DAD) was developed. The use of ultrasonication and heating improved the ability of the ionic liquid to extract the analytes. Various parameters that affect the extraction efficiency were investigated and optimized using single factor experiments and response surface design. The optimum conditions of the experiment were 121 µL of [HMIM][PF6] (extraction solvent), 794 µL of acetonitrile (dispersive solvent), a heating temperature of 40°C, a sonication time of 3.6 min and a pH of 2.9. Under optimized conditions, the linearity was in the range of 0.05–5 mg L−1 with correlation coefficients above 0.9993. The limits of detection and quantification were 1.25–1.35 µg L−1 and 5 µg L−1, respectively. The mean recoveries of the five pyrethroids ranged from 74.02% to 109.01%, with RSDs below 9.04%. The proposed method was reliable for the analysis of pyrethroids in Chinese herbal tea.

Magnetic mesoporous nanoparticles modified with poly(ionic liquids) with multi-functional groups for enrichment and determination of pyrethroid residues in apples.

Considering that the determination of pyrethroid residues is of value for the safety of food, a new poly(ionic liquid)-functionalized magnetic mesoporous nanoparticle was designed and used as an adsorbent in magnetic solid-phase extraction for the enrichment of eight pyrethroids. The porous structure and large surface area of the mesoporous silica shell endow the adsorbent with abundant binding sites. In contrast to the reported poly(ionic liquids) with only one kind of functional group in the cationic part, the new poly(ionic liquids) with mixed cyano and phenyl groups in cationic part matched the chemical structure of the analytes to improve extraction efficiency. Under the optimum conditions, an effective method was established for the determination of eight pyrethroids in apples. Adsorption equilibrium can be quickly reached in 1min, greatly decreasing the extraction time. The linearity range was found to be 10-200ng/g, and the detection limits ranged from 0.24 to 1.99ng/g. Recoveries of analytes in apple samples ranged from 87.3 to 119.0%, with relative standard deviations varying in the range of 3-21.2% (intraday) and 0.3-15.2% (interday). The results indicate that the proposed method is a good candidate for pyrethroid residues in apple samples.

New sorptive extraction method based on polydimethylsiloxane sieve combined with GC-MS for determination of pyrethroid residues in tea

In this study, a polypropylene sieve with porous network structure was coated with polydimethylsiloxane (PDMS) and used as extraction phase. Based on the PDMS-sieve, a rapid, simple and sensitive sorptive extraction method was established for analysis of five pyrethroid residues in tea samples. In the method, pyrethroids in a stirred solution were extracted on a PDMS-sieve, the analytes loaded on the sieve were then ultrasonically desorbed in ethyl acetate and analyzed by gas chromatography-mass spectrometer (GC-MS) with selected ion monitoring mode (SIM). The proposed method was optimized and validated, the matrix-matched calibration curves were performed at six concentration levels and good linear correlations (r) were obtained (r ≥ 0.9907) within the range of 0.001–0.1 μg mL−1. The detection limits (LODs) of five pesticides ranged from 0.8 ng g−1 to 19.6 ng g−1. Good repeatability was obtained with the inter- and intra-day relative standard deviation (RSDs) values lower than 10%. The method has been applied successfully to the determination of pyrethroids in six tea samples, and satisfactory recoveries ranging from 82% to 111% were obtained. The results indicated that the proposed method is suitable for trace analysis of pesticides residues in tea samples.

Determination of Pyrethroid Residues in Pork Muscle by Immunoaffinity Cleanup and GC-ECD

A method was developed to determine six pyrethroids (tau-fluvalinate, fenpropathrin, λ-cyhalothrin, cyfluthrin, α-cypermethrin and deltamethrin) in pork muscle by immunoaffinity column cleanup and gas chromatography-electron capture detection. Spiked pork muscle samples at 5, 20, 50 μg kg−1 were extracted with petroleum spirit-diethyl ether (1:1, v/v). Fat was eliminated by liquid–liquid partition between acetonitrile and petroleum spirit. An immunoaffinity column (IAC) was used for further cleanup. The IAC column was prepared by coupling the polyclonal antibodies to the protein A sepharose gel and the resulting affinity gel columns were sufficiently stable for multiple reuse. Target compounds were adsorbed at pH 7.4 and after extensive washing, eluted with 3 mL methanol. Recoveries of the six pyrethroids were typically >70%. The detection limit was 2 μg kg−1 for λ-cyhalothrin and α-cypermethrin and 5 μg kg−1 for cyfluthrin, deltamethrin, fenpropathrin and tau-fluvalinate. Repeat analyses of pork muscle samples showed good repeatability. The method was applied to detect residues in meat samples.

Determination of Pyrethroid Residues in Tobacco by Means of Solid Phase Microextraction and GC/MS with the Aid of Ultrasonic Assisted Extraction Using Water as Extracting Solvent

A rapid and simple sampling approach using solid phase microextraction (SPME) for pyrethroid residues analysis in flue-cured tobacco was studied. The fibers coated with poly-dimethylsiloxane (PDMS) at 100 microm thickness were chosen. Extraction time of 180 s, desorption time of 120 s and desorption temperature of 280 degrees C were selected. The whole sampling process, only including an ultrasonic assisted extraction step and a solid phase microextraction step, can be completed within 15 min. The associated SPME and ultrasonic assisted extraction using water as extracting solvent shows good results for tobacco pyrethroid residues determination. Results indicated that four pyrethroids can be determined simultaneously, and the limits of detection are below 35 ng g(-1) using GC/MS in selected ion monitoring (SIM) mode. The reproducibility of the technique is found to be better than 11.8% RSD.

Determination of pyrethroid residues in tobacco and cigarette smoke by capillary gas chromatography

The extraction of fenpropathrin, cyhalothrin, cypermethrin, fenvalerate and deltamethrin from tobacco ( Nicotina tobaccum) and cigarette smoke condensate with acetone, followed by partition of resulting acetone mixture with petroleum ether, was investigated and found suitable for capillary gas chromatography (GC) residue analysis. Florisil column clean-up was found to provide clean-up procedure for tobacco and cigarette smoke condensate permitting analysis to ≤0.01 μg·g −1 for most of the pyrethroids by GC with a 63Ni electron capture detector (GC–ECD). Quantitative determination was obtained by the method of external standards. Cigarettes made from flue-cured tobacco spiked with different amounts of pyrethroids were used and the pyrethroid levels in mainstream smoke were determined. For all the pyrethroid residues, 1.51–15.50% were transferred from tobacco into cigarette smoke.

Determination of Pyrethroid Residues in Vegetables, Fruits, Grains, Beans, and Green Tea Leaves: Applications to Pyrethroid Residue Monitoring Studies

Determination of natural pyrethrins and 12 synthetic pyrethroids in agricultural products was investigated. Vegetables and fruits were extracted with acetone, filtered after addition of coagulating solution, partitioned into n-hexane, and cleaned up on a Florisil column (as necessary). Pyrethroids were determined by gas chromatography/electron capture detection (GC/ECD) by using a methyl silicone-coated fused-silica capillary column, and recoveries were calculated by summing peak areas of the components. GC/mass spectrometry was used to identify the pyrethroids detected by GC/ECD monitoring. Grains and beans containing lipids were analyzed by extraction with acetonitrile, partition into n-hexane, Florisil column cleanup, and capillary GC/ECD. The coagulation method was suitable for nonfatty crops such as vegetables, fruits, and green tea leaves, because recoveries were good and Florisil column cleanup was not needed in most cases. The coagulation method was not applicable to lipid-containing crops such as grains and beans because of low recoveries. Recoveries for 18 crops at fortification levels of 0.25-1.0 ppm were 60.0-103.5%. No pyrethroids were detected from the nonfortified crops tested except green tea leaves, in which fluvalinate was detected at 0.89 ppm.

Determination of pyrethroid residues on paddy rice by reversed-phase high-performance liquid chromatography

Several synthetic pyrethroids and the synergist piperonyl butoxide have been determined as aged residues on paddy rice by reversed-phase high-performance liquid chromatography with detection at 225 nm. These compounds are commonly used as protectants for stored grains. Studies on the comparative rates of extraction of both the pesticides and interfering material from the grain were conducted with acetone, methanol, and hexane as extracting solvents. Acetone was the best of these solvents because it provided quantitative extraction of the pesticides over a 48-h period, and did not give high levels of ballast material. Pyrethroids present in the extract at levels in excess of 0.5 μg/ml could be determined by direct injection, but at lower concentrations, clean-up and preconcentration were required. Clean-up of acetone extracts was accomplished with either Florisil or alumina pre-columns, and up to a tenfold preconcentration was achieved by adsorption of the pesticide on a C 18 pre-column, or by concentrating the extract through evaporation of the solvent. These approaches gave good recoveries and linear calibration plots. Detection limits were of the order of 0.05 μg/ml.