Quantitative Determination of Fenthion in Pesticide Formulations by FT-Raman Spectroscopy

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Abstract
The Raman spectrum of the organophosphorus pesticide fenthion is presented, and a novel Fourier transform (FT)-Raman method for the quantitative determination of fenthion in pesticide formulations is proposed. Calibration curves based on Raman intensity and band area at 2951, 1065, 661, and 604 cm−1 were linear (correlation coefficients: 0.991–0.998) in the concentration range of 0.4–4.36 M. Detection limits ranged between 0.14 to 0.36 M and precision from 0.4 to 6.8% relative standard deviation (RSD) ( n = 4). Spectra normalization against the 802 cm−1 cyclohexane band proved to be effective in minimizing the effect of excitation intensity fluctuations and sample positioning changes in calibration data, resulting in improved long-term stability of the calibration curves. Results obtained during the analysis of the Lebaycid formulation compare well with those obtained by the gas chromatography (GC) reference method. The proposed FT-Raman method is fast, simple, and safe, avoids sample pretreatment, and minimizes handling of toxic samples.