Determination of iprodione in agrochemicals by infrared and Raman spectrometry

Abstract

Two methodologies based on vibrational spectrometry—making use of Fourier transform infrared absorption (FTIR) and Raman spectrometry—were developed for iprodione determination in solid pesticide formulations. The FTIR procedure involved the extraction of iprodione by CHCl₃, and the latter determination involved measuring the peak area between 1450 and 1440 cm⁻¹, corrected using a horizontal baseline defined at 1481 cm⁻¹. FT-Raman determination was performed directly on the powdered solid products, using standard chromatography glass vials as sample cells and measuring the Raman intensity between 1003 and 993 cm⁻¹, with a two-point baseline correction established between 1012 and 981 cm⁻¹. The sensitivities obtained were 0.319 area values g mg⁻¹ for FTIR determination and 5.58 area values g g⁻¹ for FT-Raman. The repeatabilities, taken to be the relative standard deviation of five independent measurements at 1.51 mg g⁻¹ and 10.98% w/w concentration levels, were equal to 0.16% and 0.9% for FTIR and FT-Raman, respectively, and the limits of detection were 0.3 and 0.2% w/w (higher than those obtained for HPLC, 0.016% w/w). FTIR determination provided a sample frequency of 60 h⁻¹, higher than those obtained for the Raman and reference chromatography methods (25 and 8.6 h⁻¹, respectively). On the other hand, the new FT-Raman method eliminates reagent consumption and waste generation, and reduces the need for sample handling and the contact of operator with the pesticide. In spite of their lack of sensitivity, vibrational procedures can therefore provide viable environmentally friendly alternatives to laborious, time- and solvent-consuming reference chromatography methods for quality control in commercially available pesticide formulations.