Thin-layer chromatography/direct analysis in real time time-of-flight mass spectrometry and isotope dilution to analyze organophosphorus insecticides in fatty foods

• Published in: Journal of Chromatography A Vol. 1370; pp. 246 - 254
• Main Authors: Kiguchi, Osamu, Oka, Kazuko, Tamada, Masafumi, Kobayashi, Takashi, Onodera, Jun
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 28.11.2014; Elsevier
• Subjects: Biological and medical sciences; Chromatography; Chromatography, High Pressure Liquid; Chromatography, Thin Layer - methods; Cleaning; Dilution; Direct analysis in real time/time-of-flight mass spectrometry; Emergencies; Fats - chemistry; Fatty food; Food Analysis - methods; Food industries; Food safety emergency; Foods; Fundamental and applied biological sciences. Psychology; General aspects; Indicator Dilution Techniques; Insecticides; Insecticides - analysis; Isotope dilution technique; Isotopes; Mass Spectrometry - methods; Methods of analysis, processing and quality control, regulation, standards; Organophosphorus insecticide; Pesticides; Phosphorus - analysis; Thin layer chromatography; Time Factors; Thin layer chromatography; Organophosphorus insecticide; Food safety emergency; Fatty food; Isotope dilution technique; Direct analysis in real time/time-of-flight mass spectrometry; Chemical analysis; Insecticide; Coupled method; Pesticides; Isotope dilution; Contamination; Time of flight mass spectroscopy; Gas chromatography; Analysis method; Residue; Direct Analysis in Real Time; Organophosphorus compounds; Food safety; Mass spectrometry; Comparative study; Food; Quantitative analysis
• ISSN: 0021-9673; 1873-3778
• DOI: 10.1016/j.chroma.2014.10.037

•We did isotope dilution and TLC/DART-TOFMS analyses of pesticides in fatty foods.•TLC/DART-TOFMS enables simultaneous analysis of polar and nonpolar organophosphorous insecticides.•TLC/DART-TOFMS is an effective tool for assessing food safety emergencies. 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 (0.05–5μg) for diazinon and EPN and at a higher standard concentration range (2.5–25μg) 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 (10mg/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.