Quantitative analysis of methanol, an adulterant in alcoholic beverages, using attenuated total reflectance spectroscopy

Abstract

To quantify methanol, a spurious adulterant in alcoholic beverages, attenuated total reflectance (ATR) technique is used. Synthetic samples (100) are prepared for developing a suitable calibration model. Spectra are recorded for all samples in wavelength region 4000-600 cm^-1 using Bio-Rad 175 C FTS spectrophotometer in ATR mode. Calibration equation is obtained using partial least squares (PLS) method. Correlation coefficient and root mean square error values for methanol are <i style="">R</i>²_cal: 0.9860, <i style="">R</i>²_val: 0.9839 and RMSEC: 0.0470, RMSEV: 0.0505. Spectral measurement is done for 10 samples and their methanol concentration (0.5-2.5%) is predicted using the developed calibration model. The reliability and repeatability of spectroscopic technique may be appreciated by the agreement between ATR predicted results to those of actual values.