Distilled spirits contain numerous phenolic constituents which are extracted, in part,
from the wood cask during maturation. Such compounds may provide information on authenticity
and quality of the products. Analyses have so far focused on the determination of
the volatile constituents by GC, including GC-MS. Few HPLC methods for whisky analysis
have been published. However, they are time-consuming [1] or afford only limited resolution
[2]. This prompted us to explore the potential of Ultra High Performance Liquid Chromatography
(UPLC) for the analysis of whiskies. UPLC is a recent development of HPLC relying
on small size particles, which increase significantly resolution and considerably
reduce separation time [3]. Using a HSS T3 column (2.1×100mm; 1.8µm, Waters) and a
gradient of methanol in water containing 0.1% TFA over 60min, more than 15 compounds,
including phenolic acids, aldehydes, phenols and furans could be identified from their
chromatographic and UV properties, and by comparison with authentic samples. In addition,
several lignans were identified after semipreparative isolation and 1H NMR measurement using a 1mm TXI microprobe (Bruker) [4].
The UPLC assay has been subsequently used for the quantification of the constituents
in a selection of Single Malt Scotch Whiskies that have been classified into ten different
clusters on the basis of their organoleptic properties collected from hundreds of
tasting notes [5].
References: [1] Goldberg, D.M. et al. (1999)J. Agr. Food Chem. 47:3978–3985.
[2] Aylott, R.I. et al. (1994) Analyst 119:1741–1746.
[3] Swartz, M.E. (2005)J. Liq. Chromatogr. R. T. 28:1253–1263.
[4] Griffin, J.L. et al. (2002) Analyst 127:582–584.
[5] Wishart, D. (2006) Whisky classified – choosing single malts by flavour. 2nd ed. Pavilion Books. London.
