Low concentration natural methanol exists in most alcoholic beverages and usually causes no immediate health threat. Nevertheless, it is possible to have natural occurring methanol in beverages with concentration as high as 18 g/L of ethanol; or equivalent to 0.72% methanol in 40% ethanol, in alcohol (1). Current EU regulation limits naturally occurring methanol to below 10 g/L of ethanol; or equivalent to 0.4% methanol in 40% ethanol.
Raman spectroscopy has been shown to be an effective tool in compositions analysis as well as adulteration identifications in foods (2). In the alcoholic beverage industry, the standard composition analysis method were more expensive and time-consuming gas chromatography (3). Here, we present a Raman spectroscopy method for a quick and lower cost alternative to verify the existence of low concentration methanol in alcohol.
An affordable, high sensitivity ProRaman instrument was used with PLS method to successfully analyze low concentration methanol in 40% alcohol. Based on our findings, the detection limit for methanol in 40% of ethanol is much better than 50 ppm and reliable quantitative determination using PLS prediction could reach 50 ppm of methanol in 40% alcohol.
(1) F. Bindler, E. Voges, and P. Laugel, Food Addit. Contam. 5, 343–351 (1988).
(2) W.M. Mackenzie and R.I. Aylott, The Analyst 129, 607–612 (2004).
(3) L.M. Reid, C.P. O'Donnell, and G. Downey, Trends in Food Science & Technology 17, 344–353 (2006).
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