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Hem, Lina,El-Aty, A.M. Abd,Park, Jong-Hyouk,Shim, Jae-Han The Korean Society for Applied Biological Chemistr 2012 Applied Biological Chemistry (Appl Biol Chem) Vol.55 No.6
This paper presents a simple and sensitive method for detection and quantification of neonicotinoids (dinotefurans) in pepper. Extraction of pesticide was carried out with acetonitrile and water partition, and passed through cleanup. The residue levels were determined by high performance liquid chromatography with UV detection and liquid chromatography-tandem mass spectrometry (LC-MS/MS) confirmation. The analytical method was very good within a wide range of concentrations with linearity ($r^2$) of 1.00. The recovery at two fortification levels ranged between 91.2 to 97.5% with relative standard deviation less than 6.0%. The method was successfully applied for determination of the analyte in pepper grown under greenhouse conditions.
Hem, Lina,Khay, Sathya,Choi, Jeong-Heui,Morgan, E.D.,El-Aty, A.M. Abd,Shim, Jae-Han Korean Society of ToxicologyKorea Environmental Mu 2010 Toxicological Research Vol.27 No.2
The pesticide trichlorfon is readily degraded under experimental conditions to dichlorvos. A method has therefore been developed by which residues of trichlorfon in milk are determined as dichlorvos, using gas chromatography with ${\mu}$-electron capture detection. The identification of dichlorvos was confirmed by mass spectrometry. Milk was extracted with acetonitrile followed by centrifugation, freezing lipid filtration, and partitioning into dichloromethane. The residue after partitioning of dichloromethane was dissolved in ethyl acetate for gas chromatography. Recovery concentration was determined at 0.5, 1.0, and 2.0 of times the maximum permitted residue limits (MRLs) for trichlorfon in milk. The average recoveries (n = 6) ranged from 92.4 to 103.6%. The repeatability of the measurements was expressed as relative standard deviations (RSDs) ranging from 3.6%, to 6.7%. Limit of detection (LOD) and limit of quantification (LOQ) were 3.7 and $11.1{\mu}g/l$, respectively. The accuracy and precision (expressed as RSD) were estimated at concentrations from 25 to $250{\mu}g/l$. The intra- and inter-day accuracy (n = 6) ranged from 89.2% to 91% and 91.3% to 96.3%, respectively. The intra- and inter-day precisions were lower than 8%. The developed method was applied to determine trichlorfon in real samples collected from the seven major cities in the Republic of Korea. No residual trichlorfon was detected in any samples.
Lina Hem,Sathya Khay,Jeong-Heui Choi,E.D. Morgan,A.M. Abd El-Aty,Jae-Han Shim 한국독성학회 2010 Toxicological Research Vol.26 No.2
The pesticide trichlorfon is readily degraded under experimental conditions to dichlorvos. A method has therefore been developed by which residues of trichlorfon in milk are determined as dichlorvos, using gas chromatography with μ-electron capture detection. The identification of dichlorvos was confirmed by mass spectrometry. Milk was extracted with acetonitrile followed by centrifugation, freezing lipid filtration, and partitioning into dichloromethane. The residue after partitioning of dichloromethane was dissolved in ethyl acetate for gas chromatography. Recovery concentration was determined at 0.5, 1.0, and 2.0 of times the maximum permitted residue limits (MRLs) for trichlorfon in milk. The average recoveries (n = 6) ranged from 92.4 to 103.6%. The repeatability of the measurements was expressed as relative standard deviations (RSDs) ranging from 3.6%, to 6.7%. Limit of detection (LOD) and limit of quantification (LOQ) were 3.7 and 11.1 ㎍/l, respectively. The accuracy and precision (expressed as RSD) were estimated at concentrations from 25 to 250 ㎍/l. The intra- and inter-day accuracy (n = 6) ranged from 89.2% to 91% and 91.3% to 96.3%, respectively. The intra- and inter-day precisions were lower than 8%. The developed method was applied to determine trichlorfon in real samples collected from the seven major cities in the Republic of Korea. No residual trichlorfon was detected in any samples.
Hem, Lina,Park, Jong-Hyouk,Shim, Jae-Han The Korean Society of Environmental Agriculture 2010 한국환경농학회지 Vol.29 No.3
In this study, the residual levels of four insecticidal compounds (lambda-cyhalothrin, lufenuron, thiamethoxam, and clothianidin) were monitored in the pomegranate, in order to assess the risk to consumers posed by the presence of such residues. The insecticides were applied at the recommended dose rates onto pomegranate trees. The samples were then collected at harvesting time after several treatments (two, three, and four treatments). After sample preparation progressed through the clean-up procedure, lufenuron, thiamethoxam, and clothianidin residues were analyzed via a HPCL-UVD, and the lambda-cyhalothrin residue was analyzed via a GC-${\mu}ECD$. The versatility of this method was evidenced by its excellent linearity (>0.9998 to 1) at broad concentration ranges. The mean recoveries evaluated from the untreated sample spiked with two different fortification levels ranged from 72.45 to 113.90%, and the repeatability (as a relative standard deviation) resulted from triplicate recovery tests was in a range from 0.80 to 11.75%. The residues of all insecticides determined from treated pomegranate samples and their LOD levels (lunfenuron, 0.01; lambda-cyhalothrin, 0.005; thiamethoxam, 0.01; clothianidin, 0.02 mg/kg) were much lower than their MRLs (0.5 mg/kg).
( Lina Hem ),( Jong Hyouk Park ),( Jae Han Shim ) 한국환경농학회 2010 한국환경농학회지 Vol.29 No.3
In this study, the residual levels of four insecticidal compounds (lambda-cyhalothrin, lufenuron, thiamethoxam, and clothianidin) were monitored in the pomegranate, in order to assess the risk to consumers posed by the presence of such residues. The insecticides were applied at the recommended dose rates onto pomegranate trees. The samples were then collected at harvesting time after several treatments (two, three, and four treatments). After sample preparation progressed through the clean-up procedure, lufenuron, thiamethoxam, and clothianidin residues were analyzed via a HPCL-UVD, and the lambda-cyhalothrin residue was analyzed via a GC-μECD. The versatility of this method was evidenced by its excellent linearity (>0.9998 to 1) at broad concentration ranges. The mean recoveries evaluated from the untreated sample spiked with two different fortification levels ranged from 72.45 to 113.90%, and the repeatability (as a relative standard deviation) resulted from triplicate recovery tests was in a range from 0.80 to 11.75%. The residues of all insecticides determined from treated pomegranate samples and their LOD levels (lunfenuron, 0.01; lambda-cyhalothrin, 0.005; thiamethoxam, 0.01; clothianidin, 0.02 mg/kg) were much lower than their MRLs (0.5 mg/kg).
Lina Hem,A. M. Abd El-Aty,Jong-Hyouk Park,JAE-HANSHIM 한국응용생명화학회 2012 Applied Biological Chemistry (Appl Biol Chem) Vol.55 No.6
This paper presents a simple and sensitive method for detection and quantification of neonicotinoids (dinotefurans) in pepper. Extraction of pesticide was carried out with acetonitrile and water partition, and passed through cleanup. The residue levels were determined by high performance liquid chromatography with UV detection and liquid chromatography-tandem mass spectrometry (LC-MS/MS) confirmation. The analytical method was very good within a wide range of concentrations with linearity (r2) of 1.00. The recovery at two fortification levels ranged between 91.2 to 97.5% with relative standard deviation less than 6.0%. The method was successfully applied for determination of the analyte in pepper grown under greenhouse conditions.