Nontargeted nuclear magnetic resonance (NMR) analysis to detect hazardous substances including methanol in unrecorded alcohol from Novosibirsk, Russia

Abstract

Nuclear magnetic resonance (NMR) spectroscopy was applied to the analysis of alcoholic products in the context of health and safety control. A total of 86 samples of unrecorded alcohol were collected in Novosibirsk and nearby cities in Russia. Sampling was based on interviews with alcohol dependent patients, and unrecorded alcohol thus defined included illegally or informally produced alcoholic products (e.g., counterfeit or home-made alcoholic beverages) or surrogate alcohol in the form of cosmetic or medicinal products and industrial non-beverage alcohol such as antifreeze (antifreeze windshield washer fluid). For sample preparation, addition of buffer and of a water/ethanol mixture was required as single step. To detect potentially harmful samples, a nontargeted approach based on principal component analysis (PCA) was applied. The PCA scores plot shows six conspicuous samples with highly divergent scores from the rest. These samples are antifreeze windshield washer fluids containing high amounts of methanol, with concentrations in a range between 7% and 48% vol. The antifreeze products were bought in regular retail sale and were claimed as “not containing methanol” on five out of six labels. Additionally, formic acid (1.1%) was observed in four of the alcohol-containing medicinal products. The major advantage of NMR over conventional methods is the fact that it not only provides the same quantitative data for specific compounds, but also allows rapid nontargeted screening for unknown contaminants.