Coffee is one of the most widely traded commodities in the world. The trade is made up of two main varieties, commonly known as Arabica and robusta, with Arabica accounting for 60–70 % of the world market and robusta most of the rest. Arabica is generally considered to be of higher quality, and sells on world commodity markets for about twice the price of robusta. There is, therefore, the potential for economic fraud, with unscrupulous traders adding robusta to Arabica and still labelling the product “100 % Arabica”. Analytical methods are therefore needed to detect the presence of robusta coffee in products labelled as Arabica.