Identifying Whiskey Counterfeits

Image Credit: PerkinElmer
Figure 1: Example separation of the involatile components of whisky, trace shows compounds detected with negative mode ionization. Labeled peaks are assigned from the accurate mass of the major component.

The problem of food and drink fraud is not new; with the increasing complexity in our supply chains it is a very real and modern problem that continues to be an issue globally. Counterfeiting of spirit brands are a major concern posing a serious health risk by providing inferior or even toxic products. Furthermore, these practices damage not only the spirits industry but also government revenues, with an estimated cost to the industry of more than $1 billion a year. According to spiritsEUROPE, it’s estimated that a quarter of products sold in China as imported spirits are actually fakes.

Analyzing Whisky with LC/MS

Adulteration is a major problem for the global drinks industry; whisky in particularly is prone to fraudulent activity with single malt Scotch whisky brands a continued target as they command a price premium. So how can suppliers within the food chain be assured of the authenticity of the products they are distributing and selling?

Image Credit: PerkinElmer
Figure 2: Negative mode Scores Plot of PC1 v PC2 shows grouping of the two Canadian (red) and four Scotch (blue) samples. Loadings plot displays the marker compounds that most strongly differentiate whiskies in negative mode.

Establishing the geographical origin offers traceability and reassurance of product quality. Malt whiskies contain a large number of compounds, which vary according to the local ingredients used, fermentation, distillation, and maturation processes. This enables the ability to build profiles of different whiskies and in turn show correlation related to geographic origin, as indicated by marker compounds that strongly correlate to location. So monitoring these marker substances in products can be used in an effort to keep control of this problem and accurately identify adulteration when it occurs.

Whiskies from different geographical origins were analyzed by both accurate mass electrospray liquid chromatography/mass spectrometry (LC/MS) and by inductively coupled plasma mass spectrometry (ICP-MS), to create a detailed profile of involatile organic and inorganic components.

Commercial Scotch and Canadian whiskies were purchased in plastic miniature bottles. The whiskies used were two Canadian blends, three Scotch blends, and one single malt Scotch. Samples were evaporated to dryness to remove ethanol and volatile components, dissolved in water, and analyzed by LC/MS to detect the low volatility compounds. Data was generated on a mass time-of-flight (TOF) instrument (PerkinElmer AxION 2 TOF and Flexar FX-15 UHPLC system) in both positive and negative modes.

Over 100 compounds were detected in total, although a few compounds were detected in both positive and negative modes; an example trace is illustrated in Figure 1. Many known compounds could be assigned from the formulas; some were identified as phenolics and terpenes, originating from the oak barrels used to mature the whiskies and from the barley used in the fermentation mash.

For elemental analysis, each whisky was evaporated to dryness, re-dissolved in an acidic solution and analyzed in collision mode using a PerkinElmer NexION 300D ICP-MS instrument. Completed analytical work essentially generates a number of different raw datasets that can be reviewed via principle component analysis.

Analysis of the negative ion mode results (see Figure 2) showed clearly resolved sample groups, with the Canadian whiskies separated from the Scotch whiskies. The loadings plot revealed significant markers with significantly different intensities between the sample groups.

Image Credit: PerkinElmer
Figure 3: Data fused organic and inorganic markers results in a Scores plot of PC1 v PC2 v PC3, showing complete separation of all the groups of whisky samples.