Over the past several years, an alarming trend has become evident, highlighting serious issues related to contaminated alcohol within the European Union, particularly Eastern Europe (1). This issue came to a breaking point in September of 2012 when the Czech Republic officially banned the sale of hard liquor after 20 people died from the consumption of methanol-laced spirits (2). After an exhaustive study of different screening tools, the Czech Republic turned to the use of portable Raman spectroscopy as the screening tool of choice for the identification and quantification of methanol in contaminated spirits. In this application note we will discuss the reasons why portable Raman spectroscopy is the ideal choice for this application and we will show a real world example of methanol-laced rum.
Raman is well recognized as an analytical tool for the discrimination of similar molecules such as ethanol (C2H50H) and methanol (CH30H) as shown in Figure 1. But what makes Raman ideally suited for this particular application over comparative technologies such as FTIR is the ability to measure through optically transparent containers and its insensitivity to interference from water. These two key properties have allowed screeners to accurately test for the presence of methanol down to ~1 % by volume in the field without the need to open the bottles being tested.
Identification and quantification of methanol in contaminated spirits