Gas Chromatography In Alcoholic Beverages Lab Report

DETERMINATION OF PERCENTAGE ETHANOL IN BEVERAGES
1. Introduction to Gas Chromatography
Gas chromatography is a very powerful separation technique for compounds that are reasonably volatile. The components of a sample partitions into two phases, the 1st of these phases is a immobile bed with a great surface area, and the other is a gas phase that permeates through the immobile bed. The sample is evaporated and passed by the mobile gas phase or the carrier gas through the column. Samples separates into the stationary liquid phase, based on their solubilities at the given temperature. The components of the sample called solutes or analytes separate from one another based on their relative vapour. This chromatographic process is called elution.

The instrument used to perform gas chromatography is called a gas chromatograph.
2. Analysis of compounds in alcoholic beverages
Alcoholic beverages comprise of a wide range of volatile compounds, together with alcohols and short chain aldehydes. Gas chromatography can be used to analyse these compounds without preliminary extractions. Alcohols and aldehydes in alcoholic beverages can be monitored by capillary G.C or packed column G.C depending on target analytes and their concentrations since capillary columns offer efficient separations, capillary G.C is particularly beneficial in analysis of structurally similar compounds.
The internal standard method allows a very accurate analysis to be performed, since the behaviour of the species of interest is compared to that of a known substance which is present in a specified amount. It is usual to include an identical volume or mass of the internal standard into each prepared standard. This facilitates easier calculations of the composition of the

Conclusion
The GC ethanol analysis method described above has a simple concept, its rapid, and extremely accurate, determining ethanol precisely without interference from other beverage components. With this method, it takes only 7 to 8 min to complete a sample analysis for the determination of ethanol content in a beverage sample. Analyst handling is minimized to prevent deviation in results or possible human error. This method requires a gas chromatograph and a digital integrator, both reasonably expensive and sophisticated pieces of equipment.
This method which uses an internal standard and flame ionisation detector, is exact and more specific than methods usually used. The gas-liquid chromatography method determines ethanol clearly and separately from the other beverage components that would have interfered in other methods, without any distillation or need for a chemical reaction. Determination of ethanol is one of the most vital routine analysis in a current winery. This method provides frequent, rapid and accurate results are needed to regulate the quality of the wine from grape to bottle, as well as for state and federal government