Simultaneous determination of chlorpyrifos and its major impurities sulfotep and 3,5,6-trichloropyridinol in the technicals of different companies by liquid chromatograph

Impurities of a pesticide, even in very small concentrations, is toxic and in some cases may be equivalent or greater than the active ingredient of the pesticide. This toxicity can be dangerous for the consumer of agricultural products as well as the environment. So, in this study, the purity percentage of chlorpyrifos as well as the amount of its two important impurities sulfotep and 3, 5, 6-trichloropyridinol (TCP) were evaluated in their technicals. The technical samples of 31 formulation companies in Iran were randomly sampled and analyzed by LC-MS/MS instrument equipped with a triple quadrupole analyzer. The results showed that 6.4% of the technical samples contained the active ingredient less than the standard limit. In 9.7% of the samples the amount of sulfotep was higher than the value recommended by FAO. The amount of TCP was higher than the standard level in 32.2% of the samples. The results of this study showed that reliable sources of the pesticide technical supplies and the evaluation of their impurities are inevitable necessities and should be given serious attention in their quality control stages.