Correct quantitative determination of ethanol and volatile compounds in alcohol products

Determination of the volume content of ethanol in the alcohol products in practice is usually determined by pycnometry, electronic densimetry, or densimetry using a hydrostatic balance in accordance with Commission Regulation No 2870/2000. However, these methods determine directly only density of the tested liquid sample and does not take into account the effects of other volatile components such as aldehydes, esters and higher alcohols. So they are appropriate only for binary water-ethanol solutions in accordance with international table adopted by the International Legal Metrology Organization in its Recommendation No 22. Availability notable concentrations of the higher alcohols and ethers in different alcohol-based products, e. g. in whisky, cognac, brandy, wine as well as in waste alcohol and alcohol beverage production, leads to the significant contribution of these compounds in the value of the density of tested alcohol-containing sample. As a result, determination of the volume of ethanol content for such alcohol products in gives the value of the strength, which may significantly differ from the true one. Using incorrectly calculated volume content of ethyl alcohol leads to incorrect results determining the quantities of volatile compounds in the alcohol-containing products, expressed in milligrams per liter of absolute alcohol. We propose experimental results of the method of correct determination of ethanol and other volatile compounds content in waste products of alcohol and alcoholic beverage industry by gas chromatography. Calculations are based on the measured value of sample density and volatile compound concentrations expressed in mg per liter of absolute alcohol [JAFC 61(2013)2950]. The method can be easily incorporated into daily practice of analytical and control laboratories with no additional material, financial or time costs.Comment: 4 pages, 2 figures, submitted to Proc. of the Wine Active Compounds (WAC) 2014 international conference (Beaune, France, March 26-28, 2014

Correct determination of alcoholic strength in alcoholic products

The paper describes a method, which combines sample density measurement data and gas chromatographic data to determine the quantitative content of volatile compounds, including ethyl alcohol, in sample. This approach can improve the accuracy of alcohol content measurements. The proposed method takes into account the presence in sample of congeners, such as methanol, fusel oils, esters and etc. The experimental study of 8 brandy samples was carried out. All samples were distillated and measured by GC-FID. The volatile compounds identified in the analyzed distillates were acetaldehyde, isobutanal, ethyl acetate, methanol, butan-2-ol, propan-1-ol, 2-methylpropan-1-ol, isoamyl acetate, butan-1-ol, 3-methylbutan-1-ol, ethyl caproate, ethyl lactate, hexanol, cis-3-hexen-1-ol, ethyl caprylate, furfural, ethyl caprate, ethyl laurate and 2-phenylethanol. The quantitative determination of congeners was carried out using ethanol as a reference substance. The sum of volume content of detected congeners in studied distillates ranged from 0.28 to 0.46%. The absolute difference between results for determination of alcoholic strength using only water-ethanol tables (traditional method) and combination of data from water-ethanol tables and gas chromatography data (proposed method) ranged from 0.22 to 0.40%

Numerical analysis of lasing dynamics in volume free electron laser

Nonlinear phenomena originating in volume free electron laser (VFEL) are investigated by methods of mathematical modelling using computer code VOLC. It was demonstrated the possibility of excitation of quasiperiodic oscillations not far from threshold values of electron beam current density and VFEL resonator length. It was investigated sensibility of numerical solution to initial conditions for different VFEL regimes of operation. Parametric maps with respect to electron beam current and detuning from synchronism condition present complicated root to chaos with windows of periodicity in VFEL. Investigation of chaotic lasing dynamics in VFEL is important in the light of experimental development of VFEL in Research Institute for Nuclear Problems. First Published Online: 14 Oct 201

X-Ray Diffraction by Time-Dependent Deformed Crystals: Theoretical Model and Numerical Analysis

arXiv publications (http://lanl.arxiv.org) arXiv:physics/9901033Comments: 19 pages, 12 figures Subjects: Computational Physics (physics.comp-ph

The intelligent use of ethanol for direct determination of methanol in wines

The results of experimental studies of the method based on the usage of ethyl alcohol as an internal standard for the direct determination of methyl alcohol in wines are presented. The method was validated in terms of precision, accuracy, limits of detection and quantification (LOD and LOQ), linearity, and robustness. The results, obtained for the developed method, were compared with the results, obtained for the official internal standard method OIV-MA-AS312-03A, using 4-methylpentan-2-ol as an internal standard. The within- and between-day precision (RSD) values of concentrations were in the ranges of 0.1-1.6% and 0.4-2.1% for the developed and official methods, correspondingly. The recovery values of concentrations were in the ranges of 99.4-101.7% and 99.4-102.3% for the developed and official methods, correspondingly. The linearity parameters R2 were 0.99996 and 0.99995 for the developed and official methods, correspondingly, as well as the LODs were 0.46 mg/L and 0.65 mg/L, the LOQs were 1.39 mg/L and 1.96 mg/L for mentioned methods. 36 samples of red, white and pink wines with different sugar levels (dry, semi-dry, semi-sweet and sweet) were studied by both developed and official methods. The relative difference between results obtained for both methods didn’t exceed ±1.5%