Determination Of Ethanol In Alcoholic Beverages Research Articles

Catalytic fuel cell used as an analytical tool for methanol and ethanol determination. Application to ethanol determination in alcoholic beverages

A small direct catalytic methanol ‘fuel cell’ was used for analytical purposes. Three different formats were investigated for methanol and ethanol determination: two different Open Circuit Voltage (OCV) formats and a potentiostatic (i.e. amperometric) format; the latter was used if the current supplied by the cell was recorded. The measurement times using one or other of these three formats were much different. The time required by the potentiostatic format was more short for a suitable analytical measurement. The cell was used to check ethanol content in several commercial wine and beer samples and the possibility of using the fuel cell for the analytical measures in real samples, discussed. Lastly the results were compared with those obtained using two conventional amperometric enzyme sensors and statistical tests carried out.

A fluorescent chemical sensor for ethanol determination in alcoholic beverages

A sensor for ethanol is described that is based on the fluorescent probe 5,10,15,20-tetraphenyl porphyrin (TPP). Response is based on the quenching of the fluorescence of TPP by ethanol as a result of electrostatic attraction. The sensor linearly responds to ethanol in the concentration range from 1 to 75 vol.% and was applied to the determination of ethanol in various kinds of wines and whisky.

A direct determination method for ethanol concentrations in alcoholic beverages employing a eukaryote double-mediator system

A fast, direct, small-sample measurement method of ethanol determination in alcoholic drinks was established by the application of attractive characteristics of a eukaryote double-mediator (EDM) system, as previously reported. The EDM system, which consists of yeast as well as both hydrophilic and hydrophobic mediators, demonstrates superior sensitivity to organic substances. For high performance, the EDM system was reoptimised for ethanol determination with a small sample volume of only 3 μL and a short incubation time of 5 min. Under optimal conditions, a practical calibration curve for ethanol determination in alcoholic beverages was obtained between 0.5 and 50 v/v% (r = 0.997, 9 points, n = 3, average of relative standard deviation, RSDav = 2.75%), with a detection limit of 0.5 v/v%. To characterise our ethanol determination method, the effects of pH, organic substances, carbon dioxide gas, or sodium sulphite on EDM responses were studied in detail. No notable effects of pH on EDM responses were observed; however, glucose and ascorbic acid strongly increased the EDM response to ethanol. Real sample applications were mainly performed using distilled alcoholic drinks (shochu, brandy, vodka, gin, and whisky) and several kinds of beer and similar beverages (lager, draft, low-malt, non-malt, and sugar-free). When the results with sugar-free beverages were compared with those obtained by the available enzymatic-spectrophotometric (ES) method, an excellent correlation was obtained (r = 0.990, 7 points, n = 3, RSDav of the EDM method = 7.90%), with an excellent slope of 1.05. Finally, a yeast suspension stored at 4 °C was stable for at least 7 days, with a response reduction of 88% (RSDav for five testing days = 4.8%).

Automatic multicommutated flow system for ethanol determination in alcoholic beverages by spectrophotometry

In this work, we describe a automatic spectrophotometric procedure for ethanol determination in alcoholic beverages by employing a flow system based on a multicommutation and binary sampling approach. The method was based on ethanol oxidation by dichromate in sulfuric acid medium and detection by spectrophotometry. The procedure was applied to ethanol determination in sugar-cane spirit, whisky, and brandy. Accuracy was assessed by comparing the results with those obtained by densimetry for sugar-cane-spirit samples and by the standard-addition technique for whisky and brandy samples. In the first case, no significant difference at the 95% confidence level was observed and in the second case, recovery ranging from 95 to 109% was achieved. Other profitable features such as an analytical throughput of 40 determinations per hour, a relative standard deviation of 1.6% (n = 11) for a typical sample presenting 42.1% (v/v) ethanol, and a reagent consumption of 5.4 mg K2Cr2O7 per determination generating a low volume of waste per determination (3.3 mL) were also achieved. © 2000 John Wiley & Sons, Inc. Lab Robotics and Automation 12:31–36, 2000

Validation of ethanol determination in alcoholic beverages by infrared spectrophotometry using orthogonal and derivative functions to correct for water absorption

The IR spectrophotometric determination of ethanol in alcoholic beverages was optimized to provide a method free from interferences. Satisfactory results were obtained with the help fo Glenn's orthogonal and first-derivative functions to correct for water absorption.