FT-Raman spectroscopy — analytical tool for routine analysis of diazinon pesticide formulations

FT-Raman spectroscopy based on band intensity and band area measurements, was used for the quantitative determination of diazinon in pesticide formulations. Bands at 554, 604, 631, 1562 and 2971 cm−1 were used for calibration. Spectra were acquired by averaging 100 scans at a resolution of 4 cm−1. Calibration curves were linear (correlation coefficients, 0.992–0.9992 and 0.99–0.999 for band intensity and band area measurements, respectively) in the range of 0.2–3.5 M for 554 and 2971 cm−1, 0.3–3.5 M for 604 cm−1, 0.6–3.5 M for 1562 cm−1 and 1.0–3.5 M for 631 cm−1 bands. Normalization of calibration curves against the 802 cm−1 cyclohexane band improved their long term stability and minimized the effect of laser beam power fluctuations. No interference was found by commonly used surfactants and the proposed method was applied to the analysis of diazinon formulations. Results obtained compare well as indicated by the t-test, with those obtained by the HPLC reference method. Precision ranged between 0.2–7.8 and 0.1–7.2% RSD, (n=4) for band intensity and band area measurements, respectively. The proposed method is rapid, simple and safe, as toxic samples are analyzed ‘as received’ without sample pre-treatment, permiting the routine analysis of pesticides formulations.