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Papers by Narong Chamkasem
Journal of the American Oil Chemists’ Society, 1988
Columns and reagent kits Complete kit 984.0000 Complete kit including 4 mm i.d. special column as... more Columns and reagent kits Complete kit 984.0000 Complete kit including 4 mm i.d. special column as a cartridge, all necessary reagents and detailed working instructions for amino acid analysis by precolumn derivatisation with FMOC/ADAM.
A simple high-throughput liquid chromatography/tandem mass spectrometry (LC-MS/MS) method was dev... more A simple high-throughput liquid chromatography/tandem mass spectrometry (LC-MS/MS) method was developed for the determination of glyphosate, aminomethylphosphonic acid (AMPA) and glufosinate in milk using a reversed-phase liquid chromatography column with weak anion/cation exchange stationary phase. One milliliter of milk was shaken with three milliliters of water containing Na 2 EDTA and acetic acid for 10 minutes, to precipitate the protein content in the sample. After centrifugation, the supernatant was passed through an Oasis HLB SPE to retain suspended particulates and phospholipids. The sample was directly injected and analyzed in 6 min, with no sample concentration or derivatization steps. Two multiple reaction monitoring (MRM) channels were monitored in the method for each target compound to achieve true positive identification. Three internal standards corresponding to each analyte were used to counter matrix suppression effects. The linearity of the detector response was ...
A high-throughput liquid chromatography/tandem mass spectrometry (LC-MS/MS) method was developed ... more A high-throughput liquid chromatography/tandem mass spectrometry (LC-MS/MS) method was developed for the determination of paraquat and diquat in potatoes using a reversed-phase with weak anion-exchange and cation-exchange mixed-mode Acclaim™ Trinity Q1 column. Five grams of sample was shaken with fifteen milliliters of 1:1 MeOH: 0.1 N HCl for 10 min at room temperature and heated for 15 min at 80°C. After centrifugation, the supernatant was passed through an Oasis HLB SPE to retain suspended particulates and non-polar interferences. The sample was directly injected and analyzed for 10 min by LC-MS/MS with no sample concentration. Two multiple reaction monitoring (MRM) channels were monitored in the method for each target compound to achieve true positive identification. Two internal standards corresponding to each analyte were used to counter matrix suppression effect. Linearity of the detector response with a minimum coefficient of determination (r 2 ) of more than 0.997 was demons...
A simple and high-throughput screening method for the analysis of pesticides in olive oil is pres... more A simple and high-throughput screening method for the analysis of pesticides in olive oil is presented. A modified QuEChERS sample preparation method was developed to improve the extraction recovery of highly lipophilic pesticides. The acetonitrile extract of the olive oil was directly injected to LC-MS/MS, while other GC-amenable compounds were treated with the modified QuEChERS procedure for GC-MS/MS analysis. The method is an extension of the LIB 4517 to include olive oil. The average recoveries for 80 pesticides quantified by LC-MS/MS at 200, 500, and 1000 ng/g fortifying levels were 91% or better (RSD < 5.5%), while GC-MS/MS analysis demonstrated 81% or better (RSD < 7.2%) for average recovery from 59 compounds at the same spike levels. This method showed an improved recovery of several challenging lipophilicpesticides in olive oils.
BACKGROUND Helicoverpa zea is managed with foliar applications of chlorantraniliprole in cotton v... more BACKGROUND Helicoverpa zea is managed with foliar applications of chlorantraniliprole in cotton varieties that do not express the Vip3Aa19 toxin in the US Cotton Belt. Foliar insecticides and Bt could interact to influence larval susceptibility. Therefore, it has been suggested that chlorantraniliprole can be used as a tool for Bt resistance management. We designed field and laboratory studies to test the hypothesis that the interaction of Bt toxin and chlorantraniliprole application would result in lower H. zea larval survival when compared to the individual effect of Bt or chlorantraniliprole alone. We also tested for these interactions over time, since chlorantraniliprole residual has not been studied in cotton. RESULTS Results from two field experiments and two laboratory experiments were similar. We found no interactions with Bt and chlorantraniliprole using data not corrected for natural mortality in untreated plots, indicating that these factors did not interact to influence ...
A simple high-throughput liquid chromatography/tandem mass spectrometry (LC-MS/MS) method was dev... more A simple high-throughput liquid chromatography/tandem mass spectrometry (LC-MS/MS) method was developed for the determination of glyphosate, glufosinate and aminomethylphosphonic acid (AMPA) in honey using a reversed-phase column with weak anion-exchange and cation-exchange mixed-mode. One gram of sample was shaken with water containing ethylenediaminetetraacetic acid disodium salt and acetic acid for five minutes. After centrifugation, the supernatant was mixed with internal standard and directly injected and analyzed in ten minutes by LC-MS/MS with no sample concentration or derivatization steps. Two precursor/product ion transitions were monitored in the method for each target compound to achieve true positive identification. Three isotopically labelled internal standards corresponding to each analyte were used to correct for matrix suppression effects and/or instrument signal drift. The average recovery for all analytes at 25, 50, 100, and 500 ng/g (n=11) ranged from 87 to 111% ...
Bulletin of the Department of Medical Sciences วารสารกรมวิทยาศาสตร์การแพทย์, Jan 13, 2014
A simple high-throughput liquid chromatography/tandem mass spectrometry (LC-MS/MS) method was dev... more A simple high-throughput liquid chromatography/tandem mass spectrometry (LC-MS/MS) method was developed for the determination of 2,4-dichlorophenoxy acetic acid (2,4-D) in soybean and corn using a reversed-phase with weak anion-exchange and cation-exchange mixed-mode Acclaim™ Trinity™ Q1 column. The method involved an alkaline hydrolysis with sodium hydroxide in order to convert all forms of 2,4-D into a salt form prior to extraction with acidified acetonitrile. The acetonitrile was salted out of the extract with sodium chloride and magnesium sulfate. The acetonitrile extract was diluted 1:1 with water and filtered before analysis by LC-MS/MS in a negative mode. Recoveries were evaluated at 10, 100, and 500 ng/g with seven replicates. Mean recovery ranged from 86 to 107% with relative standard deviation of less than 10%. Matrix suppression was not observed in this procedure; therefore, no internal standard was needed. The method was used successfully for the determination of 2,4-D ...
Journal of Environmental Science and Health, Part B
Journal of Agricultural and Food Chemistry
Analytical and Bioanalytical Chemistry
Bulletin of the Department of Medical Sciences วารสารกรมวิทยาศาสตร์การแพทย์, Dec 17, 2013
Bulletin of the Department of Medical Sciences วารสารกรมวิทยาศาสตร์การแพทย์, Dec 12, 2013
Bulletin of the Department of Medical Sciences วารสารกรมวิทยาศาสตร์การแพทย์, Oct 18, 2013
Typescript (photocopy). Thesis (Ph. D.)--Texas A & M University, 1985. Vita. Includes bibliograph... more Typescript (photocopy). Thesis (Ph. D.)--Texas A & M University, 1985. Vita. Includes bibliographical references (leaves 138-141). "Major subject: Food Science and Technology."
Food Chemistry, 2016
A simple approach to determine 19 PCB congeners in catfish tissue was presented. A modified QuECh... more A simple approach to determine 19 PCB congeners in catfish tissue was presented. A modified QuEChERS method employing high solvent to sample ratio 10:1 was used to improve the extraction recovery of 19 PCB congeners. After salting out by shaking with anhydrous magnesium sulfate and sodium chloride, 1mL of acetonitrile extract was pipetted into a 2-mL centrifuge tube containing anhydrous magnesium sulfate, primary secondary amine sorbent, and C-18 sorbent. The tube was then shaken and centrifuged to absorb fat and fatty acid residue present in the acetonitrile extract. The acetonitrile extract was analyzed by GC-MS/MS. The excellent sensitivity of GC-MS/MS allows for the direct injection of the samples to detect the low level of the PCB congeners. The method therefore is high throughput, uses fewer consumable lab supplies, and provides excellent sensitivity with an LOQ below 1ng/g.
Journal of the American Oil Chemists’ Society, 1988
Columns and reagent kits Complete kit 984.0000 Complete kit including 4 mm i.d. special column as... more Columns and reagent kits Complete kit 984.0000 Complete kit including 4 mm i.d. special column as a cartridge, all necessary reagents and detailed working instructions for amino acid analysis by precolumn derivatisation with FMOC/ADAM.
A simple high-throughput liquid chromatography/tandem mass spectrometry (LC-MS/MS) method was dev... more A simple high-throughput liquid chromatography/tandem mass spectrometry (LC-MS/MS) method was developed for the determination of glyphosate, aminomethylphosphonic acid (AMPA) and glufosinate in milk using a reversed-phase liquid chromatography column with weak anion/cation exchange stationary phase. One milliliter of milk was shaken with three milliliters of water containing Na 2 EDTA and acetic acid for 10 minutes, to precipitate the protein content in the sample. After centrifugation, the supernatant was passed through an Oasis HLB SPE to retain suspended particulates and phospholipids. The sample was directly injected and analyzed in 6 min, with no sample concentration or derivatization steps. Two multiple reaction monitoring (MRM) channels were monitored in the method for each target compound to achieve true positive identification. Three internal standards corresponding to each analyte were used to counter matrix suppression effects. The linearity of the detector response was ...
A high-throughput liquid chromatography/tandem mass spectrometry (LC-MS/MS) method was developed ... more A high-throughput liquid chromatography/tandem mass spectrometry (LC-MS/MS) method was developed for the determination of paraquat and diquat in potatoes using a reversed-phase with weak anion-exchange and cation-exchange mixed-mode Acclaim™ Trinity Q1 column. Five grams of sample was shaken with fifteen milliliters of 1:1 MeOH: 0.1 N HCl for 10 min at room temperature and heated for 15 min at 80°C. After centrifugation, the supernatant was passed through an Oasis HLB SPE to retain suspended particulates and non-polar interferences. The sample was directly injected and analyzed for 10 min by LC-MS/MS with no sample concentration. Two multiple reaction monitoring (MRM) channels were monitored in the method for each target compound to achieve true positive identification. Two internal standards corresponding to each analyte were used to counter matrix suppression effect. Linearity of the detector response with a minimum coefficient of determination (r 2 ) of more than 0.997 was demons...
A simple and high-throughput screening method for the analysis of pesticides in olive oil is pres... more A simple and high-throughput screening method for the analysis of pesticides in olive oil is presented. A modified QuEChERS sample preparation method was developed to improve the extraction recovery of highly lipophilic pesticides. The acetonitrile extract of the olive oil was directly injected to LC-MS/MS, while other GC-amenable compounds were treated with the modified QuEChERS procedure for GC-MS/MS analysis. The method is an extension of the LIB 4517 to include olive oil. The average recoveries for 80 pesticides quantified by LC-MS/MS at 200, 500, and 1000 ng/g fortifying levels were 91% or better (RSD < 5.5%), while GC-MS/MS analysis demonstrated 81% or better (RSD < 7.2%) for average recovery from 59 compounds at the same spike levels. This method showed an improved recovery of several challenging lipophilicpesticides in olive oils.
BACKGROUND Helicoverpa zea is managed with foliar applications of chlorantraniliprole in cotton v... more BACKGROUND Helicoverpa zea is managed with foliar applications of chlorantraniliprole in cotton varieties that do not express the Vip3Aa19 toxin in the US Cotton Belt. Foliar insecticides and Bt could interact to influence larval susceptibility. Therefore, it has been suggested that chlorantraniliprole can be used as a tool for Bt resistance management. We designed field and laboratory studies to test the hypothesis that the interaction of Bt toxin and chlorantraniliprole application would result in lower H. zea larval survival when compared to the individual effect of Bt or chlorantraniliprole alone. We also tested for these interactions over time, since chlorantraniliprole residual has not been studied in cotton. RESULTS Results from two field experiments and two laboratory experiments were similar. We found no interactions with Bt and chlorantraniliprole using data not corrected for natural mortality in untreated plots, indicating that these factors did not interact to influence ...
A simple high-throughput liquid chromatography/tandem mass spectrometry (LC-MS/MS) method was dev... more A simple high-throughput liquid chromatography/tandem mass spectrometry (LC-MS/MS) method was developed for the determination of glyphosate, glufosinate and aminomethylphosphonic acid (AMPA) in honey using a reversed-phase column with weak anion-exchange and cation-exchange mixed-mode. One gram of sample was shaken with water containing ethylenediaminetetraacetic acid disodium salt and acetic acid for five minutes. After centrifugation, the supernatant was mixed with internal standard and directly injected and analyzed in ten minutes by LC-MS/MS with no sample concentration or derivatization steps. Two precursor/product ion transitions were monitored in the method for each target compound to achieve true positive identification. Three isotopically labelled internal standards corresponding to each analyte were used to correct for matrix suppression effects and/or instrument signal drift. The average recovery for all analytes at 25, 50, 100, and 500 ng/g (n=11) ranged from 87 to 111% ...
Bulletin of the Department of Medical Sciences วารสารกรมวิทยาศาสตร์การแพทย์, Jan 13, 2014
A simple high-throughput liquid chromatography/tandem mass spectrometry (LC-MS/MS) method was dev... more A simple high-throughput liquid chromatography/tandem mass spectrometry (LC-MS/MS) method was developed for the determination of 2,4-dichlorophenoxy acetic acid (2,4-D) in soybean and corn using a reversed-phase with weak anion-exchange and cation-exchange mixed-mode Acclaim™ Trinity™ Q1 column. The method involved an alkaline hydrolysis with sodium hydroxide in order to convert all forms of 2,4-D into a salt form prior to extraction with acidified acetonitrile. The acetonitrile was salted out of the extract with sodium chloride and magnesium sulfate. The acetonitrile extract was diluted 1:1 with water and filtered before analysis by LC-MS/MS in a negative mode. Recoveries were evaluated at 10, 100, and 500 ng/g with seven replicates. Mean recovery ranged from 86 to 107% with relative standard deviation of less than 10%. Matrix suppression was not observed in this procedure; therefore, no internal standard was needed. The method was used successfully for the determination of 2,4-D ...
Journal of Environmental Science and Health, Part B
Journal of Agricultural and Food Chemistry
Analytical and Bioanalytical Chemistry
Bulletin of the Department of Medical Sciences วารสารกรมวิทยาศาสตร์การแพทย์, Dec 17, 2013
Bulletin of the Department of Medical Sciences วารสารกรมวิทยาศาสตร์การแพทย์, Dec 12, 2013
Bulletin of the Department of Medical Sciences วารสารกรมวิทยาศาสตร์การแพทย์, Oct 18, 2013
Typescript (photocopy). Thesis (Ph. D.)--Texas A & M University, 1985. Vita. Includes bibliograph... more Typescript (photocopy). Thesis (Ph. D.)--Texas A & M University, 1985. Vita. Includes bibliographical references (leaves 138-141). "Major subject: Food Science and Technology."
Food Chemistry, 2016
A simple approach to determine 19 PCB congeners in catfish tissue was presented. A modified QuECh... more A simple approach to determine 19 PCB congeners in catfish tissue was presented. A modified QuEChERS method employing high solvent to sample ratio 10:1 was used to improve the extraction recovery of 19 PCB congeners. After salting out by shaking with anhydrous magnesium sulfate and sodium chloride, 1mL of acetonitrile extract was pipetted into a 2-mL centrifuge tube containing anhydrous magnesium sulfate, primary secondary amine sorbent, and C-18 sorbent. The tube was then shaken and centrifuged to absorb fat and fatty acid residue present in the acetonitrile extract. The acetonitrile extract was analyzed by GC-MS/MS. The excellent sensitivity of GC-MS/MS allows for the direct injection of the samples to detect the low level of the PCB congeners. The method therefore is high throughput, uses fewer consumable lab supplies, and provides excellent sensitivity with an LOQ below 1ng/g.