Application of near infrared spectroscopy to control the protective reaction in the synthesis of emamectin benzoate

摘要

A near infrared (NIR) method was developed for the control of the protective reaction in the synthesis of emamectin benzoate. A NIR spectrometer with a fibre-optic probe was used to analyse the residual content of avermectin and the by-product content of the shield. Partial least squares regression was used to develop the calibration models, which for the residual content were preprocessed by second derivative and for the by-product content by first derivative and straight-line subtraction preprocessing methods. After optimising the spectral pre-treatment, the coefficient of determination (R~2) of the residual content and by-product content were 0.92 and 0.99 and the root mean square errors of calibration were 0.18% and 0.46%, respectively. When the models were used to determine the residual content and by-product content, the root mean square errors of prediction were 0.20% and 0.48%, respectively. These preliminary findings suggest that the NIR method could be used to predict the residual content and by-product content simultaneously and the process could be completed within 2 min without sample destruction. The control of the protective reaction could be adjusted according to the results obtained using the NIR method. The results indicated that information contained in NIR spectra may be useful to control the protective reaction in the synthesis of the emamectin benzoate.