Simultaneous determination of ethanol and methanol in alcohol free malt beverages, energy drinks and fruit juices by gas chromatography
Ala Yahya Sirhan1,2*, Richard C.S. Wong 3, Lukman Bola Abdulra’uf4, Joumana Abd Aljabar2, Ahmad Mostafa2, Ahmad Talhouni5
1Dept. of Basic Science, Applied Science Private University, 11931 Amman, Jordan
2Food Lab Dept., Jordan Food & Drug Administration, Amman, Jordan
3Dept. of Chemistry, Faculty of Science, Universiti Malaya, Lembah Pantai, 50603 Kuala Lumpur, Malaysia
4Dept. of Chemistry, College of Pure and Applied Sciences, Kwara State University, Malete, P.M.B. 1530, Ilorin, Nigeria
5Faculty of Pharmacy, Isra’ University, 11622 Amman, Jordan
Abstract
A simple, sensitive, and direct method to decide if “alcohol-free” beverages, energy drinks and fruit juices could result in positive “alcohol alerts” based on the use of the gas chromatography with a flame ionization detector (GC– FID) has been developed. The chromatographic conditions such as injection volume and split ratios were optimized in order to increase the sample throughput and sensitivity. Unlike other conventional methods which also employ laborious sample preparations; this method analyzes samples directly without any prior treatment and thus cutting down the sample treatment time, as well as reducing the analysis cost per sample. Additionally, low ethanol concentrations as low as 6 mg/L were detected and quantified; making this method an appropriate technique for routine alcohols analysis in beverages. Optimization of chromatographic conditions gave recoveries in the range of 83.00% to 112.8% with relative standard deviations lower than 9%. The calibration curves were linear over the range from 6.250-200.0 mg/L for methanol and ethanol. The correlation coefficients (r2) were higher than 0.9997. The limits of quantifications (LOQ) are 4.48 mg/L for ethanol and 5.74 mg/L for methanol. A total of 100 domestic and imported labeled "alcohol-free" in Jordan were analyzed for their alcohol content. Concentrations ranged from non-detectable to 14.9 mg/L for ethanol and from non-detectable to 9.38 mg/L for methanol were found in energy drinks. On the other hand, non- quantifiable amounts of alcohols were found in malt beverage as well as fruit juices.
Keywords: Alcohol-free beverage, Energy drink, Flame ionization detector, Gas chromatography
