The principal goal of this work was to develop an efficient method for the simultaneous determination of four pyrethroid (PYR) insecticides, cyfluthrin, cyhalothrin, cypermethrin, and deltamethrin, in porcine muscle and pasteurized milk using liquid-liquid extraction (LLE). Sample extraction was carried out with and without additional column cleanup procedures, and the final determination was made using GC with electron-capture detector (ECD). The pesticide identity was confirmed using GC-MS in the SIM mode. Since there were minor differences between the extraction procedures, extraction without the additional cleanup procedure was used throughout the work. The method was validated by fortifying blank samples with half, two, and four times the maximum residue limit (MRL) of each PYR. The average recoveries (n = 6) ranged from 83.5 to 99.2% and 82.9 to 109% in porcine muscle and pasteurized milk, respectively. The repeatability of measurements expressed as RSDs, was in the range of 1.7-11.9 and 1.5-10.3% in porcine muscle and pasteurized milk, respectively. The LODs ranged from 3.3 to 9 and 3 to 8.1 ppm, whereas the LOQs ranged from 10 to 27.4 and 9 to 24.6 ppm, in porcine muscle and pasteurized milk, respectively. The applicability of the method was demonstrated by analyzing real samples collected from major cities in the Republic of Korea. No residues of the selected pesticides were detected in any of the samples.

Simultaneous determination of pyrethroids from pesticide residues in porcine muscle and pasteurized milk using GC.

A novel method was developed for the determination of eight pyrethroids in water samples by liquid–liquid microextraction based on solidification of floating organic droplets followed by gas chromatography with electron capture detection. The type and volume of the extraction solvents, extraction time, sample solution temperature, stirring rate and ionic strength were studied and optimized. Under the optimum conditions, enrichment factors ranged from 824 to 1,432, and the limit of detection range from 2.0 to 50 ng∙L−1. The calibration graph is linear from 0.15 to 80 μg∙L−1 for cyfluthrin, fenvalerate, fluvalinate and deltamethrin, 0.09 to 80 μg∙L−1 for fenpropathrin, 0.006 to 80 μg∙L−1 for lambda-cyhalothrin, 0.026 to 80 μg∙L−1 for permethrin, 0.01 to 80 μg∙L−1 for cypermethrin. The correlation coefficients (r) varied from 0.9961 to 0.9988. The method was successfully applied to the determination of pyrethroid pesticide residues in tap water, well water, reservoir water, and river water. Recoveries ranged from 79.0% to 113.6%, and relative standard deviations are between 4.1% and 8.7%.

Analysis of eight pyrethroids in water samples by liquid–liquid microextraction based on solidification of floating organic droplet combined with gas chromatography

In this study, a simplified method for the extraction and determination of seven fluoroquinolone residues (danofloxacin, difloxacin, enrofloxacin, marbofloxacin, orbifloxacin, ofloxacin, and sarafloxacin) and three quinolones (oxolinic acid, flumequine, and nalidixic acid), in porcine muscle, table eggs, and commercial whole milk, which required no cleanup step, was devised. This procedure involves the extraction of analytes from the samples via liquid-phase extraction, and the subsequent quantitative determination was accomplished via LC-fluorescence detection. Analyte separation was successfully conducted on an XBridge-C(18) column, with a linear gradient mobile phase composed of acetonitrile and 0.01 M oxalic acid buffer at pH=3.5. The one-step liquid-liquid extraction method evidenced good selectivity, precision (RSDs=0.26-15.07%), and recovery of the extractable analytes, ranging from 61.12 to 115.93% in matrices. The LOQs ranged from 0.3 to 25 microg/kg. A survey of ten samples purchased from local markets was conducted, and none of the samples harbored fluoroquinolone residues. This method is an improvement over existing methodologies, since no additional cleanup was necessary.

Single-step extraction followed by LC for determination of (fluoro)quinolone drug residues in muscle, eggs, and milk

The principal goal of this work was to develop an efficient method for the simulta- neous determination of four pyrethroid (PYR) insecticides, cyfluthrin, cyhalothrin, cypermethrin, and deltamethrin, in porcine muscle and pasteurized milk using liquid - liquid extraction (LLE). Sample extraction was carried out with and without additional column cleanup procedures, and the final determination was made using GC with electron-capture detector (ECD). The pesticide identity was confirmed using GC-MS in the SIM mode. Since there were minor differences between the extraction procedures, extraction without the additional cleanup procedure was used throughout the work. The method was validated by fortifying blank samples with half, two, and four times the maximum residue limit (MRL) of each PYR. The average recoveries (n = 6) ranged from 83.5 to 99.2% and 82.9 to 109% in porcine muscle and pasteurized milk, respectively. The repeatability of measurements expressed as RSDs, was in the range of 1.7 - 11.9 and 1.5 - 10.3% in porcine muscle and pasteurized milk, respectively. The LODs ranged from 3.3 to 9 and 3 to 8.1 ppm, whereas the LOQs ranged from 10 to 27.4 and 9 to 24.6 ppm, in porcine muscle and pasteurized milk, respectively. The applicability of the method was demonstrated by analyzing real samples collected from major cities in the Republic of Korea. No residues of the selected pesticides were detected in any of the samples.

Original Paper Simultaneous determination of pyrethroids from pesticide residues in porcine muscle and pasteurized milk using GC

The methods of simultaneous extraction of iprodione, chlorpyrifos-methyl, EPN and endosulfan (with its metabolites) from kiwi fruit using accelerated solvent extraction (ASE), supercritical fluid extraction (SFE), and liquid-liquid extraction (LLE) were tested and compared in terms of their of limits of detection and quantification, as well as the highest pesticide recoveries with the lowest residues in the final extracts. The analysis was performed using gas chromatography-mass spectrometry in the selected ion monitoring mode. The proposed methods featured good sensitivity, pesticide quantification limits were low enough, and the precision (expressed as relative standard deviations) ranged from 0.56 to 7.17%. The recoveries obtained from ASE, SFE and LLE were 77.5-120, 71.9-109.1 and 75.6-127.1%, respectively. The proposed methods were successfully applied for the monitoring of the selected pesticide residues in kiwi fruit samples collected from Jollanamdo area, Republic of Korea. Iprodione was detected at a level lower than the maximum residue limit (MRL) established by the Korea Food and Drug Administration (5 ppm), while EPN was detected at a level higher than the Korea Food and Drug Administration MRL (0.1 ppm) in the real samples. The proposed sample preparations led to a higher preconcentration of the pesticide fraction, and allowed the sensitive and selective determination of pesticides with varied physicochemical properties in kiwi fruit.

Comparison of different extraction methods for the simultaneous determination of pesticide residues in kiwi fruit using gas chromatography–mass spectrometry

We evaluated a procedure that uses high-performance liquid chromatography to determine the levels of four fluoroquinolones (ciprofloxacin, enrofloxacin, norfloxacin, and ofloxacin) remaining in chicken breast muscle, liver, and kidneys after the analytes are extracted using supercritical fluid extraction (SFE) These antimicrobial fluoroquinolones were extracted by SFE using supercritical CO2 containing 30% (v/v) methanol The recovery, limit of detection, accuracy, and precision of this method were evaluated on the basis of fortified matrices at concentrations of 25 to 250 microg/kg The method is validated and shown to be linear in the range of 25-50 microg/kg Spike recoveries for muscle, liver and kidney samples prepared at 4 spiking levels were ranged from 566-1043%, 512-984% and 622-978%, respectively The coefficient of variation (CV) for recovery as a measure of relative variability was between 3% and 13%, and the relative standard deviation (RSD) was < 20% The limits of quantitation (LOQ) were 10 microg/kg for enrofloxacin, 125 microg/kg each for ciprofloxacin and norfloxacin and 25 microg/kg for ofloxacin; these values were lower than the maximum residue levels (MRLs) authorized by the European Community The 4 compounds were evaluated simultaneously, and the method was shown to be applicable for analyzing their residues in edible chicken tissues

Analysis of fluoroquinolone residues in edible chicken tissues using supercritical fluid extraction.

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Analysis of fluoroquinolone residues in edible chicken tissues using supercritical fluid extraction.