Simultaneous Determination of 18 Bioactive Compounds in Italian Bitter Liqueurs by Reversed-Phase High-Performance Liquid Chromatography–Diode Array Detection

A simple, fast and accurate method has been developed to simultaneously determine 18 bioactive compounds in Italian bitter liqueurs containing gentian, cinchona, cinnamon, rhubarb, clove, star anise or orange, by reversed-phase high-performance liquid chromatography (RP-HPLC) coupled with diode array detection (DAD). HPLC analysis was performed with a C18 column using methanol and aqueous phosphoric acid (pH 2.5) as mobile phase. Selected wavelengths, i.e. 210, 232, 275, 285, 291, 310 and 368 nm, were used for quantification of compounds. The column temperature was controlled at 30 °C. The correlation coefficients (R2) of the calibration curves of the analysed compounds were ≥0.9999 in a relatively wide concentration range (0.5–50 μg/ml). The proposed method proved successful in simultaneously analysing 18 bitter liqueurs produced in Italy. The concentration of the most important bitter principles, gentiopicroside, amarogentin, quinine and naringin, ranged as follows: 1.17–299.20, 0.25–32.24, 1.44–6.93 and 0.28–39.99 μg/ml, respectively.