Determination of Methanol in Alcoholic Beverages by Two-Dimensional Near-Infrared Correlation Spectroscopy

Abstract

ABSTRACTAn innovative method for the determination of concentration of methanol in white spirit was proposed using two-dimensional near-infrared (NIR) correlation spectroscopy in combination with multivariate calibration. A total of 38 white spirit samples were adulterated with level of methanol varying from 0.1 to 10%. A one-dimensional NIR spectra of all samples were collected. Spectral characteristics of white spirit adulterated with methanol were studied based on one-dimensional NIR spectra and two-dimensional NIR correlation spectra. The origin of 4396 cm−1 peak of methanol was verified in terms of the existence or absence of cross-peaks in synchronous and asynchronous two-dimensional NIR correlation spectra. For comparison, the quantitative analysis models were constructed to determine content of methanol in white spirit using synchronous two-dimensional NIR correlation spectra and traditional one-dimensional NIR spectra, respectively. The prediction statistics criteria for synchronous two-dimensional NIR correlation spectra using N-way partial least squares, average relative error and root mean square error, were 2.97 and 0.064%, respectively. For traditional one-dimensional NIR spectra using partial least squares method, average relative error and root mean square error of prediction were 5.3 and 0.079%, respectively. Comparison results show that the proposed new method has stronger predictive ability and can provide better results than traditional one-dimensional NIR spectra using partial least squares.