Simultaneous determination of chlorpyrifos and its most important impurities

The toxicity of the impurities of a pesticide, even in very small concentrations, in some cases may be equal to or greater than the active substance of the pesticide. This toxicity can be dangerous for the consumer of agricultural products as well as the environment. Therefore, the control of these impurities is very important in pesticide technology. Based on this, in a research conducted by Iran’s Herbal Medicine Research Institute, the percentage of technical purity of chlorpyrifos and the amount of two important impurities including sulfotop and 3, 5, and 6-trichloropyridinol or TCP were investigated. For this purpose, technical chlorpyrifos belonging to 31 formulating companies was randomly sampled and analyzed. An LC-MS/MS device equipped with a triple quadrupole analyzer was used for analysis. The results showed that 6.4% of the technical samples containing the effective substance were less than the permissible limit. In 9.7% of the samples, the amount of Sulfotep was higher than the allowed amount recommended by FAO, and in more than 32.2% of the samples, the amount of TCP was higher than the allowed amount. The results of this research showed that the technical supply of pesticides from reliable sources and checking the level of their impurities is an inevitable necessity and should be given serious attention in their quality control stages.