Thin-layer chromatography/direct analysis in real time time-of-flight mass spectrometry and isotope dilution to analyze organophosphorus insecticides in fatty foods. Kiguchi, O., Oka, K., Tamada, M., Kobayashi, T., & Onodera, J. Journal of Chromatography A.
Thin-layer chromatography/direct analysis in real time time-of-flight mass spectrometry and isotope dilution to analyze organophosphorus insecticides in fatty foods [link]Paper  doi  abstract   bibtex   
Abstract To assess food safety emergencies caused by highly hazardous chemical-tainted foods, simultaneous analysis of organophosphorus insecticides in fatty foods such as precooked foods was conducted using thin-layer chromatography/direct analysis in real time time-of-flight mass spectrometry (TLC/DART-TOFMS) and isotope dilution technique. Polar (methamidophos and acephate) and nonpolar organophosphorus insecticides (fenitrothion, diazinon, and EPN) were studied. Experiments to ascertain chromatographic patterns using TLC/DART-TOFMS reveal that it was more useful than GC/MS or GC/MS/MS for the simultaneous analyses of polar and nonpolar pesticides, while obviating the addition of a protective agent for tailing effects of polar pesticides. Lower helium gas temperature (260 °C) for DART-TOFMS was suitable for the simultaneous analysis of target pesticides. Linearities were achieved respectively at a lower standard concentration range (0.05–5 μg) for diazinon and EPN and at a higher standard concentration range (2.5–25 μg) for methamidophos, acephate, and fenitrothion. Their respective coefficients of determination were≥0.9989 and ≥0.9959. A few higher repeatabilities (RSDs) for diazinon and EPN were found (\>20%), although isotope dilution technique was used. Application to the HPTLC plate without an automatic TLC sampler might be inferred as a cause of their higher RSDs. Detection limits were estimated in the higher picogram range for diazinon and EPN, and in the lower nanogram range for methamidophos, acephate, and fenitrothion. Aside from methamidophos, recovery results (n = 3) obtained using a highly insecticide-tainted fatty food (dumpling) and raw food (grapefruit) samples (10 mg/kg) using TLC/DART-TOFMS with both complex and simpler cleanups were not as susceptible to matrix effects (95–121%; RSD, 1.3–14%) as those using GC/MS/MS (102–117%; RSD, 0.4–8.5%), although dumpling samples using GC/MS were remarkably susceptible to matrix effects. The coupled method of TLC with simpler cleanup and DART-TOFMS can be regarded as the same analytical tool as GC/MS/MS, which is useful to assess food safety emergencies caused by highly hazardous chemical-tainted foods.
@article{ kiguchi_thin-layer_????,
  title = {Thin-layer chromatography/direct analysis in real time time-of-flight mass spectrometry and isotope dilution to analyze organophosphorus insecticides in fatty foods},
  issn = {0021-9673},
  url = {http://www.sciencedirect.com/science/article/pii/S0021967314016094},
  doi = {10.1016/j.chroma.2014.10.037},
  abstract = {Abstract
To assess food safety emergencies caused by highly hazardous chemical-tainted foods, simultaneous analysis of organophosphorus insecticides in fatty foods such as precooked foods was conducted using thin-layer chromatography/direct analysis in real time time-of-flight mass spectrometry ({TLC}/{DART}-{TOFMS}) and isotope dilution technique. Polar (methamidophos and acephate) and nonpolar organophosphorus insecticides (fenitrothion, diazinon, and {EPN}) were studied. Experiments to ascertain chromatographic patterns using {TLC}/{DART}-{TOFMS} reveal that it was more useful than {GC}/{MS} or {GC}/{MS}/{MS} for the simultaneous analyses of polar and nonpolar pesticides, while obviating the addition of a protective agent for tailing effects of polar pesticides. Lower helium gas temperature (260 °C) for {DART}-{TOFMS} was suitable for the simultaneous analysis of target pesticides. Linearities were achieved respectively at a lower standard concentration range (0.05–5 μg) for diazinon and {EPN} and at a higher standard concentration range (2.5–25 μg) for methamidophos, acephate, and fenitrothion. Their respective coefficients of determination were≥0.9989 and ≥0.9959. A few higher repeatabilities ({RSDs}) for diazinon and {EPN} were found (\>20%), although isotope dilution technique was used. Application to the {HPTLC} plate without an automatic {TLC} sampler might be inferred as a cause of their higher {RSDs}. Detection limits were estimated in the higher picogram range for diazinon and {EPN}, and in the lower nanogram range for methamidophos, acephate, and fenitrothion. Aside from methamidophos, recovery results (n = 3) obtained using a highly insecticide-tainted fatty food (dumpling) and raw food (grapefruit) samples (10 mg/kg) using {TLC}/{DART}-{TOFMS} with both complex and simpler cleanups were not as susceptible to matrix effects (95–121%; {RSD}, 1.3–14%) as those using {GC}/{MS}/{MS} (102–117%; {RSD}, 0.4–8.5%), although dumpling samples using {GC}/{MS} were remarkably susceptible to matrix effects. The coupled method of {TLC} with simpler cleanup and {DART}-{TOFMS} can be regarded as the same analytical tool as {GC}/{MS}/{MS}, which is useful to assess food safety emergencies caused by highly hazardous chemical-tainted foods.},
  number = {0},
  journal = {Journal of Chromatography A},
  author = {Kiguchi, Osamu and Oka, Kazuko and Tamada, Masafumi and Kobayashi, Takashi and Onodera, Jun},
  keywords = {direct analysis in real time/time-of-flight mass spectrometry, fatty food, food safety emergency, isotope dilution technique, organophosphorus insecticide, thin layer chromatography}
}
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