Chlorogenic acid composition of instant coffees

A method, based on high-performance liquid chromatography, is described for the determination of chlorogenic acid isomers in instant coffee. Identification of the individual components was assisted by the preparation of isomeric mixtures by the isomerisation of available compounds and quantification based on published ultraviolet molar absorptivities. A number of extraction and clearing techniques were studied to determine the optimum conditions for the recovery of all the isomers present. The developed method was applied to a wide range of commercially available instant coffees.