## 3 Results  
The Principal Component Analysis was performed on the FTIR and SPME-GCMS data separately. Figure 1 shows the 2D PCA scores plot based on the FTIR data for samples from distillery 0 and distillery 1. These distilleries were chosen as they had more samples. No significant difference could be discerned between distilleries. None of the other distilleries could be positively differentiated based on the FTIR data. Performing the PCA using the SPME-GCMS data, however, did show some distinct patterns. The scores plot using SPME-GCMS data, accounting for 60.4% of the data variance, is shown in Figure 2. Samples from distillery 1 are clearly different to distillery 0. The biplot showed that the major chemical differences between distillery 0 and 1 were an increase in ethyl esters (specifically ethyl propanoate, ethyl butanoate, ethyl isobutanoate, ethyl pentanoate, and ethyl hexanoate)in samples from distillery 1 compared to distillery 0. Similar chemical differences were also true, to a lesser extent, for distillery 3, although only two samples were available from this distillery. Distilleries 4 and 6 were also found to be discernable using SPME-GCMS data. Only single samples were available from each of these distilleries. Both samples had a distinct lack of ethyl esters, containing only a few small peaks associated with alkanes and alkenes. Ethyl esters form via esterification reactions between organic acids and ethanol. [PERSON] et al. (2018) found that long-chain fatty acid ethyl esters were absent from baijiu samples that had been matured for less than a year; however, short and medium chain fatty acid ethyl esters were detected. It is suspicious, therefore, that no ethyl esters could be detected in these samples. qNMR spectra also demonstrated a lack of ethyl esters in these two samples. Figure 3 shows the PCA scores plot for all samples categorized by percent alcohol by volume (%ABV) range. This suggests that FTIR could be used as a quick, first step in the authentication of a suspect sample by providing an approximate %ABV. Samples with high %ABV had higher absorbances at 2970 (C-H stretch), 2900, 1985, and 1048 (C-O stretch) cm\({}^{-1}\). It is of note that not all samples fell in the expected areas of the scores plot in terms of alcohol content. One sample, for example, listed at an ABV of 40%, appears to the right of the region of samples below 40% ABV, suggesting that the actual ABV is significantly below 40%. qNMR determined this sample to have an alcohol content of just 29% ABV. Figure 1: A PCA scores plot based on FTIR spectra obtained from two distilleries. Shaded areas are the 95% confidence regions. A typical baijiu \({}^{1}\)H-NMR spectrum is shown in Figure 4 with the assignment of the observable congeners. The spectrum is obtained using a pre-saturation pulse centered on the water peak, effectively suppressing that peak. On the instrument used to generate the NMR data, it was not possible to suppress the ethanol CH\({}_{3}\) and CH\({}_{2}\) peaks at 1.16 and 3.63 ppm. These signals are very intense and are presented on a scale such that they are greatly off-scale. The congeners that are observed are dominated by ethyl esters, which provide signals from the ethyl CH\({}_{2}\) protons in the 4.0-4.50 ppm region of the spectrum. Ethyl acetate and ethyl lactate are found to dominate most of the baijiu samples, with many of the light aroma samples showing the presence of only ethyl acetate, ethyl lactate, and lactic acid above the limit-of-detection of the experiment. Other large congener signals are observed in the 0.84-0.95 ppm region, which represent the methyl resonances of 1-propanol and isopentanol. In the 2.0-2.5 ppm region, the signals from the methyl resonances of acetaldehyde, acetic acid, and ethyl acetate can be observed. This region also shows signals from the CH\({}_{2}\) adjacent to the ester and acid carboxyl in butyric, caproate, and other ethyl esters and carboxylic acids.