2B-O1-0920 PDF
Use of Stable Carbon Isotope Ratios to Determine the Source of Cypermethrin in So-Called Natural Plant Extract Formulations Used for Organic Farming
Some natural plant extract formulations (NPEFs, also referred to as essential oils) used in organic farming have been shown to contain synthetic pesticides. we used gas chromatography coupled with combustion, cryofocusing, and isotope ratio mass spectrometry to determine the stable carbon isotope ratios (δ13C) for the cypermethrin in the four NPEF samples, as well as in ten cypermethrin reagents and two commercial pesticide formulations (Agrothrin emulsion and Agrothrin water-dispersible powder). The δ13C values (± standard deviation) of the 16 cypermethrin samples ranged from -28.3 ± 0.2‰ to -24.5 ± 0.2‰. Surprisingly, the four NPEFs showed similar δ13C values (-26.8‰ to -27.3‰), suggesting that the cypermethrin in all the samples came from the same source (either the same chemical reaction or the same primary material).