Chromatographic and Voltammetric Characterization of Chlorogenic Acids in Coffee Samples

The accurate and precise characterization of eight chlorogenic acids (CGAs) isomers, caffeoylquinic acids (5-CQA, 4-CQA, 3-CQA), dicaffeoylquinic acids (3,5-diCQA, 4,5-diCQA, 3,4-diCQA), and feruloylquinic acids (5-FQA, 4-FQA), was carried out using different brands of coffee. High-performance liquid chromatography (HPLC), differential pulse (DPV) and square-wave voltammetry (SWV) were applied for the investigation. HPLC proved to be an accurate and precise method for separation, identification and quantification of CGAs isomers in coffee extracts. DPV and SWV have shown that electrochemical behaviour of coffee extracts was very similar to that of CGAs isomers and DPV and SWV can be used for the correct characterization of CGAs in coffee. All three techniques have shown a very high correlation of CGAs content in all investigated coffee samples. Therefore, HPLC, DPV and SWV methods can be used in combination as very selective, sensitive and precise methods for characterization of CGAs isomers in coffee extracts. Keywords: voltammetry, HPLC, chlorogenic acids, coffee.