Analysis of Whiskey by Dispersive Liquid–Liquid Microextraction Coupled with Gas Chromatography/Mass Spectrometry: An Upper Division Analytical Chemistry Experiment Guided by Green Chemistry

Abstract

Analysis of whiskey samples prepared by a green microextraction technique, dispersive liquid–liquid microextraction (DLLME), before analysis by a qualitative gas chromatography–mass spectrometry (GC/MS) method, is described as a laboratory experiment for an upper division instrumental methods of analysis laboratory course. Here, aroma compounds in whiskey samples (n = 11) were extracted using ultrasound-assisted DLLME with chloroform (as extraction solvent). The chloroform extract was analyzed by GC/MS with data manipulation by AMDIS (automated mass spectral deconvolution and identification system) to allow for comparisons between whiskey samples. Aroma compounds commonly reported in the literature (furfural, isoamyl acetate, 5-methyl furfural, ethyl esters, phenylethyl alcohol, whiskeylactone, and vanillin) were tentatively identified based upon the match to the MS library. This unique laboratory allows students to engage in a real-world analysis of a high-value product and to explore the use of AMDIS to tentatively identify compounds and compare chromatographic profiles of various whiskey samples for identification of common and unique constituents. Students also use the literature to provide sensory information for these identified semivolatile compounds.

Formation of Clusters in Whiskies During the Maturation Process

“…To measure the absolute concentrations of the main compounds in whiskies, high‐performance liquid chromatography (HPLC) analysis was conducted. Although whiskies consist of a wide variety of compounds, 12 well‐known major compounds (Nose et al., ; Owens, Zimmerman, Gardner, & Lowe, ) (Figure S1) were quantified in this work. The total concentration c Total of the 12 compounds increases fairly proportionally as the maturation time t mat increases, as shown in Figure S2.…”

Chromatographic fingerprint application possibilities in food authentication

“…The method used allowed for a good differentiation of distillates. Whereas the authors of [45] found discrete compounds in various types of whiskey for didactic purposes, and then the chromatographic profiles obtained by the GC/MS method were used to identify the whiskey. The analytical procedure was based on dispersive microextraction with chloroform.…”

Comparison of unaged and barrel aged whiskies from the same Mash Bill using gas chromatography/mass spectrometry

“…GC/MS separates and identifies components of complex sensory compound mixtures (Gates and Bull, 2008). Sensory compound profiles are dependent on the type of whisky being tested (such as bourbon, Scotch, and Canadian) (Piggott, 2016) and show similarities among different whiskies for the major volatile congeners they contain (Owens et al, 2016). Russell and Stewart (2014) also found that of the spectrometric analysis methods available, chromatography offers advantages in speed, selectivity and sensitivity.…”

“…Sensory compounds of interest found in the whisky samples in this study. The sensory descriptors are taken from other works synthesized by Owens et al (2016).…”