Products Safety Inspection Laboratory

Gwangsan Gu, South Korea

Products Safety Inspection Laboratory

Gwangsan Gu, South Korea

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Choi J.-H.,Chonnam National University | Mamun M.I.R.,University of Dhaka | Abd El-Aty A.M.,Cairo University | Park J.-H.,Chonnam National University | And 6 more authors.
Food Chemistry | Year: 2011

In this study, we describe a newly developed and simple analytical method using high-performance liquid chromatography coupled to fluorescence detector (HPLC-FLD) for the determination of enrofloxacin, ciprofloxacin, and danofloxacin in porcine plasma. A single-step sample preparation, including extraction with acidic acetonitrile, coagulation with ammonium acetate, and centrifugation made possible the direct analysis of plasma samples without the need for any further cleanup procedure. The developed method was validated with specificity, linearity, limit of detection (LOD), limit of quantitation (LOQ), accuracy, and precision. All results were fully adequate. In the study using porcine plasma incurring enrofloxacin, the developed method proved capable of quantifying concentrations below its maximum residue limit, and its time-course residues were excreted within the 10-day withdrawal time. © 2011 Elsevier Ltd. All rights reserved.


Cho S.-K.,Products Safety Inspection Laboratory | Abd El-Aty A.M.,Cairo University | Park K.H.,Chonnam National University | Park J.-H.,Chonnam National University | And 4 more authors.
Food Chemistry | Year: 2013

A simple multiresidue analytical method is developed for the simultaneous determination of carbendazim (CB), thiabendazole (TB), and 6-benzyl aminopurine (6-BA) in bean sprouts. The samples were extracted with acetonitrile followed by partitioning at -80 °C for 5-10 min. A YMC C8 column was used to separate the analytes before being qualitatively and quantitatively determined by liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) in positive ion mode using multiple reaction monitoring (MRM). The matrix-matched calibration curves showed good linearity in the range 0.01-1.0 mg/kg with correlation coefficients in excess of 0.998. The mean recoveries were in the range of 80.4-96.3% at 0.1 and 0.5 spiked levels, and the relative standard deviations (RSDs) were in the range of 0.5-7.6%. The limits of quantifications (LOQ) were in the range of 0.005-0.01 mg/kg. The method was successfully applied to 90 samples (among which 45 were organic) collected from a commercial bean sprout production house throughout the city. Except for 6-BA, the rest of the analytes had values lower than their LOQs. In sum, carbendazim, thiabendazole, and 6-BA were extracted in a single step, and no steps for clean-up or concentration of the extracts were needed. The current method can be used for sensitive and accurate determination and confirmation of residues in bean sprout samples. © 2012 Elsevier Ltd. All rights reserved.


Jang J.,Chonnam National University | Rahman M.M.,Chonnam National University | Ko A.-Y.,Chonnam National University | Abd El-Aty A.M.,Chonnam National University | And 4 more authors.
Food Chemistry | Year: 2014

A gas chromatography (GC) method for the analysis of pymetrozine was developed after utilizing matrix enhancement effect of pymetrozine to nitrogen phosphorus detector (NPD). Samples were extracted with acetonitrile and purified through primary secondary amine (PSA) and C18 dispersive sorbent. Matrix-matched calibration curve prepared after spiking standard pymetrozine across the studied range of concentrations (0.003-1.0 mg/L) into blank red pepper extract was excellent with a determination coefficients (R2) = 1. Recovery studies were carried out at three concentration levels (0.04, 0.4, and 2.0 mg/kg, n = 3) and the rates were ranged between 77.2% and 109.1%, with relative standard deviations ranged from 1.3% to 16.4%. The developed method was applied to field samples to characterize the dissipation pattern, half life, and pre-harvest residue limits (PHRL). The dissipation rates of the analyte were ascribed to first-order kinetics with half-life of 2.7 and 2.5 days for recommended and double the recommended doses. From the PHRL curve, we could predict that if the residue level of pymetrozine is below the 1.23 mg/kg at 10 days or 0.71 mg/kg at 7 days before harvest, then the residues will be below the maximum residue limits (MRL = 0.2 mg/kg) established by the Korea Food and Drug Administration (KFDA). © 2013 Elsevier Ltd. All rights reserved.


Cho S.-K.,Products Safety Inspection Laboratory | Abd El-Aty A.M.,Chonnam National University | Abd El-Aty A.M.,Cairo University | Rahman M.M.,Chonnam National University | And 2 more authors.
Food Chemistry | Year: 2014

A method for determining eight pesticide (cyhalothrin, flufenoxuron, fenitrothion, EPN, bifenthrin, difenoconazole, triflumizole, and azoxystrobin) residues in made green tea as well as a tea infusion (under various brewing water temperatures; 60, 80, and 100 °C) using gas chromatography (GC) micro-electron capture detector (μECD) was developed and validated. The extraction method adopted the relatively commonly used approach of solid sample hydration, with the green tea hydrated before being extracted through salting out with acetonitrile followed by a cleanup procedure. The analytes were confirmed using GC-coupled to tandem mass spectrometry (GC/MS/MS) with a triple quadrupole. The linearity of the calibration curves yielded determination coefficients (R2) >0.995. Recoveries were carried out using blank samples spiked with all analytes at two levels. The results demonstrated that all pesticides were recovered within the range of 77-116% with a relative standard deviation (RSD) ≤14%. The quantification limits of 0.015-0.03 mg/kg were lower than the maximum residue limits (MRLs) set by the Korea Food and Drug Administration (KFDA) for all analytes (0.05-10 mg/kg). The infusion study indicated that cyhalothrin, flufenoxuron, and bifenthrin did not infuse into the tea brew from the made tea. Increases in brewing time resulted in increased transfer of azoxystrobin, fenitrothion, and difenoconazole from the made tea to the brew; however, this was not the case with triflumizole or EPN. We conclude that transfer of pesticides appeared to be dependent on their water solubilities and drinking a cup of tea is recommended to be at a water temperature of 60 °C. © 2014 Elsevier Ltd. All rights reserved.


Hem L.,Chonnam National University | Choi J.-H.,Chonnam National University | Park J.-H.,Chonnam National University | Mamun M.I.R.,University of Dhaka | And 3 more authors.
Food Chemistry | Year: 2011

Fenhexamid (25%, SC) was sprayed on pepper fruits grown under greenhouse conditions at the recommended dose rate of 20 g/20 L water. Fruit samples were collected randomly at 0 (2 h after application), 1, 2, 4, 6, 8, 11, and 14 days post-application. The samples were extracted with acetonitrile, partitioned with water, passed through a cleanup procedure, and analysed via HPLC. Residues were confirmed via LC-tandem mass spectrometry (LC-MS/MS) in positive-ion electrospray ionisation (ESI+) mode. The rate of disappearance of fenhexamid on pepper fruits was described as first-order kinetics (r2 = 0.992) with a half-life of 4.7-day. Based on the pattern of decline of the fungicide residues in relation to the estimated maximum residue limits (MRL = 5 mg/kg), a safety pre-harvest interval of 1 day is suggested for peppers at the recommended dosage. © 2010 Elsevier Ltd. All rights reserved.


Liu X.,Chonnam National University | Liu X.,Jiangnan University | Abd El-Aty A.M.,Cairo University | Cho S.-K.,Products Safety Inspection Laboratory | And 3 more authors.
Biomedical Chromatography | Year: 2012

The extraction and identification of bioactive compounds from herbs is of great interest. In this study, accelerated solvent extraction (ASE) technique was used to analyze the secondary volatile profiles in Nigella sativa seeds obtained from two different origins, Egypt and Bangladesh. The main extraction parameters, including extraction temperature, pressure and static extraction time, were investigated and optimized. Identification and quantification of the major constituents in nonpolar extracts (hexane) were achieved by means of GC-FID/GC-MS analysis with external standards. The two seeds showed a similar variety of chemical composition; however, the secondary volatiles profile of Bangladesh seed was higher than that of the Egyptian seed. A total of 25 compounds were identified from the ASE extract under the following optimum extraction conditions: 100°C, 1500psi and 5min, for extraction temperature, pressure and static time, respectively. The proposed technique can be used for the characterization of N. sativa varieties or cultivars. © 2012 JohnWiley & Sons, Ltd.


Lee S.W.,Products Safety Inspection Laboratory | Choi J.-H.,Chonnam National University | Cho S.-K.,Products Safety Inspection Laboratory | Yu H.-A.,Products Safety Inspection Laboratory | And 2 more authors.
Journal of Chromatography A | Year: 2011

This study describes a new QuEChERS method referred to as the dry ice-partitioning QuEChERS method. This current method can be differentiated from the other QuEChERS methods in the sense that it uses dry ice rather than salts or buffers to extract and partition pesticides in the first extraction step. The dry ice-partitioning QuEChERS method consists of extraction method A (for detection of the acetonitrile layer) and extraction method B (for detection of both acetonitrile and aqueous layers). The extraction efficiency was then compared with the citrate-buffering QuEChERS method by means of recovery. Recovery values of the tested 168 pesticides were above 76%, with relative standard deviations of less than 20%. Certain problematic pesticides, including benfuracarb, carbosulfan, dichlofluanid, probenazole, pymetrozine, tolylfluanid, TFNA, and TFNG evidenced acceptable recoveries via the dry ice-partitioning QuEChERS method compared to the less than 70% recoveries of the citrate-buffering QuEChERS method examined herein. The matrix effect of paprika on the method developed herein was not significant, and matrix-matched calibration was performed well, with an r2≥0.99. The dry ice-partitioning QuEChERS method is capable of detecting the aqueous layer as well as the acetonitrile layer; this interesting feature makes it worth in application as an alternative QuEChERS method for the multiresidue analysis of pesticides within a broad polarity range in various matrices. © 2011 Elsevier B.V.


Rahman M.M.,Chonnam National University | Park J.-H.,Chonnam National University | Abd El-Aty A.M.,Cairo University | Choi J.-H.,TU Dortmund | And 4 more authors.
Journal of Separation Science | Year: 2013

A new method was developed for kresoxim-methyl (parent compound) and its two thermolabile metabolites, BF 490-2 and BF 490-9, in Korean plum, introducing pepper leaf matrix as a natural analyte protectant for GC-amenable metabolites using a GC-electron capture detector. Samples were extracted with a simple and rapid method using a mixture of ethyl acetate-n-hexane (1:1) and salts, and purified via SPE. Due to the elution gap between parent compound and metabolites in the SPE cartridge and matrix interference, kresoxim-methyl was isolated separately from its metabolites. An optimized amount of pepper leaf matrix (0.25 g/mL) was added to the metabolites prior to each injection. Calibration curves were linear over the concentration ranges with coefficient of determination (r2) ≥ 0.999. The method was validated in triplicate at two fortification levels, giving recoveries ranging between 74.3 and 101.4%, and RSDs less than 5%. The LOD and LOQ were 0.015 and 0.05 mg/kg, respectively. The method was successfully applied to real samples where kresoxim-methyl residues were detected in field-incurred plum samples. Residues were confirmed using GC-MS. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


PubMed | Products Safety Inspection Laboratory, Chonnam National University and Konkuk University
Type: Journal Article | Journal: Biomedical chromatography : BMC | Year: 2015

In this study, a simple, rapid, and sensitive method was developed for the extraction of ethephon from homogenized tomatoes that does not require a cleanup procedure. In a syringe filter, three distinct layers - aqueous, acetonitrile, and n-hexane - are clearly separated after storage at -80C for 5-10min. A Dionex IonPac column was used to separate the analyte before detection using negative-ion mode liquid chromatography with tandem mass spectrometry (LC/MS/MS). The matrix effect of the tested analyte was negligibly small and the matched calibration showed a good linearity over a concentration range of 0.01-1.0mg/kg with a correlation coefficient (R(2) ) of 0.9998. The recovery at three fortification levels (0.1, 0.5 and 1.0mg/kg) was between 82.9 and 108.6% with relative standard deviations (RSDs) <5.0%. The limit of quantification (0.03mg/kg) was lower than the maximum residue limit (3mg/kg) set by the Ministry of Food and Drug Safety, Republic of Korea. From a field trial, the method developed herein was applied to calculate the decline pattern and predict the pre-harvest residue limits of ethephon in tomatoes. In conclusion, the proposed sample preparation is feasible for the detection of hydrophilic analytes in tomatoes.


Ko A.-Y.,Gwangju University | Rahman M.M.,Gwangju University | Abd El-Aty A.M.,Gwangju University | Abd El-Aty A.M.,Cairo University | And 4 more authors.
Food Chemistry | Year: 2014

Simple extraction and optimised oxidation procedures were developed for the determination of the total residues of imidacloprid and its metabolites (containing the 6-chloropicolyl moiety) in lettuce using a gas chromatography-micro electron capture detector (GC-μECD). Samples were extracted with acetonitrile, and the extract was then evaporated. The remaining residues were dissolved in water and oxidised with potassium permanganate to yield 6-chloronicotinic acid (6-CAN). The acid residues were further dissolved in n-hexane:acetone (8:2, v/v) and then silylated with MSTFA (N-methyl-N-(trimethylsilyl)trifluoroacetamide) to 6-chloronicotinic acid trimethylsilyl ester. Calibration curves were linear over the concentration ranges (0.025-5 μg mL-1) with a determination coefficient (r 2) of 0.991. The limits of detection and quantification were 0.015 and 0.05 mg kg-1, respectively. Recoveries at two fortification levels ranged between 72.8% and 108.3% with relative standard deviation (RSD) lower than 8%. The method was effective, and sensitive enough to determine the total residues of imidacloprid and its metabolites in field-incurred lettuce samples. The identity of the analyte was confirmed using gas chromatography-tandem mass spectrometry (GC-MS/MS).©2010 H. Jafari and H. Tajadodi.

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