Posted by: Hourglass PJ2 MAY 2012
As pharmacists we often find it interesting to distinguish between natural and synthetic ingredients. Caffeine is an example of an ingredient that is present naturally in drinks such as coffee, tea, guarana and maté and is also found in “energy drinks” and cola-type soft drinks that usually contain synthetic caffeine.
The difference between natural and synthetic sources of caffeine has relevance for EU food labelling rules, which state that caffeine should be declared in ingredient lists when added as a flavouring but need not appear on the labels of drinks such as tea and coffee in which it naturally occurs.
Since synthetic caffeine is less expensive than naturally occurring caffeine sources, there is a potential for fraud by false declaration of caffeine ingredients. Various methods of analysis have been used to discriminate between natural and synthetic caffeine, but they require extraction of caffeine from the drink and tend to be time consuming.
To test drinks directly and avoid extraction of the caffeine, analytical chemists from Germany have developed a new method involving high temperature liquid chromatography coupled to isotope ratio mass spectrometry.
By analysing 42 natural caffeine samples (including coffee beans, tea leaves, guarana powder and maté leaves) and 20 synthetic caffeine samples, the researchers showed the ratios of carbon isotopes could distinguish between natural plant chemicals and petroleum-based chemicals.
They went on to analyse 38 drinks at grocery stores, four of which — an instant coffee, two ices teas and one maté — were mislabelled:?they contained synthetic caffeine that was not labelled as such.