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%.