Paper spray ionization mass spectrometry allied to chemometric tools for quantification of whisky adulteration with additions of sugarcane spirit

Abstract

Whisky is one of the most commercialized distilled beverages in the world. Due to its large commercialization, the number of cases involving the adulteration of this beverage has increased. This work highlights the application of paper spray ionization mass spectrometry (PS-MS) in order to quantify whisky adulteration with additions of sugarcane spirit (i.e., the cachaça). 19 binary mixtures (0; 0.5; 1; 3; 5; 10; 20; 30; 40; 50; 60; 70; 80; 90; 95; 97; 99; 99.5; and 100 wt% of cachaça in whisky) were analyzed by PS-MS in both ionization modes, positive and negative, (PS(±)). Two chemometric models (using a partial least squares (PLS)) were designed to quantify the cachaça content in whisky:cachaça blends. The PS(±) mass spectrum of pure samples of whisky contained several signals in the m/z 250–900 region; the addition of the adulterant caused the suppression of the signals in the m/z 200–350 region, primarily, while the relative intensity of ions in the m/z > 350 region increased. These changes occur due to the increase of sugar concentration as a function of the addition of cachaça. When combining the PS(±) mass spectra with chemometric tools, such as PCA, it becomes clear that the first three main components describe the degree of adulteration for whisky samples along their negative and positive quadrants. The multivariate calibration model with variable selection, CARSPLS, presented a satisfactory linearity (R² > 0.92) among the measured and predicted values, with RMSEP <10.9% v/v and LOD values of ≈13% v/v. In addition, a better accuracy was observed for the constructed CARSPLS model in the PS(−), yielding R² and RMSEP values of 0.9592 and 7.97% v/v, respectively.