Cheers to GC!
As you stockpile your favorite beverage ahead of New Year celebrations, we ask: what does gas chromatography bring to beer, wine and whisky analysis? Richard Law has the answers...
Richard Law |
sponsored by Thermo Fisher Scientific
When I think about key advances in gas chromatography, the birth of the capillary column actually stands out as the biggest game changer – despite the fact that it was a long time ago. I guess some major advances are never superseded (although I know of people who are still working in the ‘Dark Ages’ with packed columns, believe it or not). The leap in performance afforded by capillary columns really opened GC up to a much broader set of applications; I’ve personally analyzed everything from Wellington boots to Silly String – both of which may also feature in your end of year celebrations...
Fancy a beer?
Liisa Otama covered the “BeerMaster” Analyzer in an earlier article of this “Cheers!” series (http://tas.txp.to/1216/beermaster), but gas chromatography still has a role to play. For example, diketones are important natural ingredients in beer aroma and characterized by their ‘buttery’ flavor, but to lager manufacturers, they are considered ‘off-flavors’ and must be carefully monitored. In 1999, the European Brewery Convention (EBC) issued a method for the determination of vicinal diketones (2,3-butanedione and 2,3-pentanedione) in beers via headspace GC. The EBC method is especially challenging because it demands that samples are incubated at 35°C, which necessitates the use of expensive cryogenic systems (unless you have access to a Thermo Scientific™ TriPlus™ 300 headspace autosampler and its ability to operate at 35°C without such systems...). You can find more information about the autosampler and the use of GC-MS in diketone analysis in an application note devoted to the EBC method here: http://tas.txp.to/1216/beer.
Or perhaps a glass of wine?
To the wine drinkers among you, it’s most likely obvious that wine aroma and flavor is dictated by a highly complex mixture of compounds. Notably, certain chemical impurities are key indicators of quality; examples include volatile phenol compounds (from yeast metabolism) and haloanisoles (from cork fungal infections). Though few analytical techniques can compete with the nose and taste buds of an experienced wine guru, GC-MS has proven itself to be an excellent companion. Indeed, the identification and quantitation of maturation tracers and the molecules commonly responsible for taste defects has become an important part of modern day quality control.
In fact, the Thermo Scientific ISQ™ Single Quadrupole GC-MS system is able to detect a number of wine contaminants at lower concentrations than its human counterparts. Couple that sensitivity with ease of use and rapid single-step sample preparation and wineries have a new go-to tool for impurity analysis. Learn more about GC-MS analysis of various critical compounds in wine here: http://tas.txp.to/1216/wine
How about a whisky nightcap?
Delving deeper into increasingly complex samples using GC is an ongoing trend that is only made possible by the increasing accuracy and sensitivity of modern MS systems. The introduction of the Thermo Scientific Exactive™ GC Orbitrap™ GC-MS and Q Exactive GC Orbitrap GC-MS/MS systems take gas chromatography into the exciting territory of high-resolution accurate mass (HRAM) measurements, opening up yet more potential application areas.
Jana Hajšlová (Professor and Laboratory Head, Department of Food Chemistry and Analysis, University of Chemistry and Technology, Prague, Czech Republic) has been applying GC-HRAM MS analysis in an attempt to protect Scottish whisky from fraudsters who go to great lengths to benefit from the expensive spirit. When it comes to tackling counterfeit or adulterated whisky (or any complex beverage sample for that matter), comprehensive ‘fingerprinting’ using full-scan HRAM data (and advanced chemometrics) is king of authentication, and is able to provide more information in a single run than ever before.
By building up databases and statistical models from whisky samples of known origin using the Q Exactive GC Orbitrap GC-MS/MS, Hajšlová and her team hope to be able to assess the authenticity of unknown samples using HRAM fingerprints. You can read Hajšlová’s proof-of-concept in an application note that delves into much more detail here: http://tas.txp.to/1216/whisky.
Although capillary columns have been around longer than most of us have been able to legally enjoy an alcoholic drink or two, gas chromatography (especially coupled with cutting-edge autosamplers and MS systems) looks set to see us through a good few more New Year’s celebrations yet. Cheers to GC and Happy New Year!