A new portable device to measure the strength of alcoholic drinks promises to help retailers and authorities identify dangerous illicit alcohol supplies.

The device, developed by German testing agency CVUA, can be used on-site in less than a minute, and is as accurate as widely-used laboratory methods.

The measurement technology combines a patented multiple-beam infrared sensor with a flow-through cell for automated alcohol analysis.

The agency's team tested the device on 260 different alcoholic drinks. Their system was found to be equal to or better than current laboratory analysers in its precision and reliability.

Analysis of unrecorded (non-commercial or illicit) alcohol samples was also accurate. Time-consuming sample preparation was not needed for wine or spirits, though it was for beer and other fizzy drinks.

"The device gives the opportunity for mobile on-site control in the context of labelling control of wine, beer and spirits, the process monitoring of fermentations, or the evaluation of unrecorded alcohols," said Dirk Lachenmeier of CVUA.

The researchers noted that unrecorded alcohol accounts for a quarter of all alcohol consumed worldwide, and that in most cases "not even the most basic chemical composition such as alcoholic strength is known for these beverages".

Traditionally, scientists have measured alcoholic strength by per cent volume, using distillation and density measurement. Infrared spectroscopy, a more recent method, typically requires expensive equipment and is a slow process.