SIMULTANEOUS DETERMINATION OF CHLOROGENIC ACIDS AND CAFFEINE BY REVERSED-PHASE HPLC

A variant of simultaneous determination of chlorogenic (monocaffeoylquinic and dicaffeoylquinic) acids and caffeine in coffee (drink) using reversed-phase chromatography with spectrophotometric detection has been developed. For separation, a gradient mode is proposed explor-ing of two components of the mobile phase containing 3 vol.% of formic acid and 6 and 20 vol.% ace-tonitrile in distilled water and chromatographic column 150x4.6 mm Symmetry C18, 3.5 mu m. Col-umn thermostat temperature is 30 degrees C. The choice of the type and concentration of the acidifier of the mobile phase is justified in the work. It has been established that the acidity of the mobile phases should not be lower than pH 2 in order to transfer most of the chlorogenic acids to the non-ionized state. The dependences of the retention of monocaffeoylquinic acids and caffeine on the concen-tration of acetonitrile and formic acid, which is more effective in the selectivity of separation com-pared to orthophosphoric acid in the mobile phase, are determined. The selectivity of the separation of these compounds depends more on the concentration of formic acid than on the concentration of acetonitrile. Concentrations of chlorogenic acids and caffeine were determined in drinks from two varieties of coffee, coffee husk (dried pericarp of coffee fruits) (produced in Vietnam) and for comparison of two more variants - Arabica coffee from roasted grains and from green decaffein-ated grains from other manufacturers. It is shown that coffee husk is a valuable raw material for the preparation of an alternative drink. Thus, when using 1 g of coffee husk when brewing 100 ml of boiling water, a drink containing about 10 mg (per 100 ml) of monocaffeoylquinic acids, about 6 mg of dicaffeoylquinic acids and about 3 mg of caffeine was obtained.