A validated and fast procedure for FTIR determination of Cypermethrin and Chlorpyrifos

A FTIR methodology has been developed for the simultaneous determination of Cypermethrin and Chlorpyrifos in pesticide commercially available formulations. The method involves the extraction of both active principles with CHCl₃ and direct measurement of the peak area values between 1747 and 1737 cm⁻¹ corrected with a baseline defined at 2000 cm⁻¹ for Cypermethrin and peak height values established at 1549 cm⁻¹ corrected using a baseline situated at 1650 cm⁻¹ for Chlorpyrifos.The limits of detection achieved were of the order of 0.7 and 0.4% (w/w), and the relative standard deviation 0.4 and 0.2% for Cypermethrin and Chlorpyrifos, respectively. The developed procedure provided statistically comparable results with those obtained by HPLC, for a series of commercial samples, which validated the FTIR method. The procedure developed reduces organic solvent consumption, per sample preparation, from 51 ml CH₃CN required for HPLC to 2.5 ml CHCl₃, and reduces waste generation also increasing the sample measurement frequency, from 3 to 30 samples/h, as compared with the HPLC-UV reference method.