Methyl-Parathion Determination by FT-Raman Spectroscopy

  • Raman bands observed at 634, 661, 1113, 1348 and 1527 cm-1 are used for univariate calibration.
  • Calibration curves are linear with correlation coefficients of  0.996-0.998 and 0.994-0.999 for band intensity and band area measurements respectively. The linear range is 0.6-3.75 M for the 634, 661 and 1527 cm-1 bands, 0.05-3.75 M for the 1113 cm-1 band, and 0.1-3.75 M for the 1348 cm-1 band. 
  • Precision ranges between 0.5-5.2 and 0.1-6.8 % RSD (n=4) for band intensity and band area measurements respectively.
  • Spectra normalization against the 802 cm-1 cyclohexane band improved the long-term stability of calibration allowing the use of calibration data acquired up to 3 months prior to analysis.
  • The application of the method was extended through multivariate calibration by multiple linear regression using the 858 and 2952  cm-1 bands.
  • Results obtained by the proposed FT-Raman method are equivalent to those acquired through the reference HPLC method.
  • Multivariate calibration based on stepwise linear regression was found to be superior to univariate calibration in terms of concentration prediction.

Raman spectra acquired during calibration

Standards of  (a) 0.0500, (b) 0.300, (c ) 0.600, (d) 1.00, (e) 1.50, (f) 2.00, (g) 2.50 (h) 3.00 and (i) 3.75 M methyl-parathion.

Predicted vs. true concentration

Using (A) band intensity and (B) band area measurements

Questions and comments to author: Dr C.A. Georgiou, cag@aua.gr
Phone: +3010-5294248, fax: +3010-5294265
Chemistry Laboratory, Agricultural University of Athens, Greece