Caffeine Source: A Bean, A Leaf, Or A Lab

Is your caffeinated buzz from a natural or artificial source? Researchers in Germany have now developed an easy way to determine whether drinks contain natural or synthetic caffeine (Anal. Chem., DOI: 10.1021/ac203197d).

Under Food & Drug Administration regulations, when manufacturers add caffeine to drinks, such as sodas or energy drinks, they must mention it on the label. But labels for tea, coffee, and other naturally caffeinated drinks don’t need to list caffeine. Because synthetic caffeine is less expensive than natural caffeine, unscrupulous manufacturers may slip in the synthetic version and pass off the drink as a naturally caffeinated beverage, ignoring the labeling requirement.

Existing methods to discriminate between natural and synthetic caffeine require extracting the caffeine from the drink, which makes them time consuming and laborious, explains analytical chemist Maik A. Jochmann at the University of Duisburg-Essen in Germany. To test beverages directly and avoid extraction, Jochmann and colleagues developed a method with high-temperature liquid chromatography and isotope ratio mass spectrometry. By analyzing 42 naturally caffeinated and 20 artificially caffeinated drinks, the investigators showed that the carbon isotope ratios could distinguish between the two types of caffeine. Carbon isotope ratios depend on the origin of the material, explains Jochmann: plants versus petroleum-based laboratory chemicals.

Jochmann and colleagues next analyzed 38 drinks purchased at grocery stores. They found four—an instant coffee, two iced teas, and one maté, which is a South American herb that can be brewed like tea—that explicitly claimed to contain natural caffeine but contained synthetic. Jochmann declines to reveal the identity of the mislabeled brands but says his lab’s approach “has the potential to become a routine method for authenticity control of caffeine-containing drinks.”