Determination of seven polyphenols in water by high performance liquid chromatography combined with preconcentration

A method for determination of seven polyphenols (chlorogenic acid, esculetin, caffeic acid, scopoletin, rutin, quercetin hydrate, kaempferol) by reversed-phase high performance liquid chromatography (RP-HPLC) combined with preconcentration was developed. The preconcentration was accomplished by adsorption–desorption method with a styrene-divinylbenzene resin (XAD-4), and the analytes were desorbed by methanol. The parameters of adsorption and desorption, such as the amounts of resin, adsorption time, pH of the adsorption solution, and the volume of methanol for desorption were optimized. RP-HPLC with photodiode array detector (PAD) was employed for the qualitative and quantitative analysis. Methanol and acetic–water (1:99, v/v) solution were used as the mobile phase, and a gradient program was established for separation. Calibration curves of the seven analytes were obtained in the range of 0.8–3 mg L−1, with correlation coefficients (R) higher than 0.9990. With standard samples, the recoveries for the preconcentration step under optimal conditions were 93–99%, and the relative standard deviations were 0.2–2.0% (n = 5). Polyphenols in simulated tobacco-polluted water were analyzed with the optimized conditions. Chlorogenic acid and rutin were found and determined, whose concentrations were 32.8 and 19.2 μg L−1, respectively. The spiked recoveries of the polyphenols were 83–95% except quercetin hydrate (63%), the relative standard deviations were less than 3.5% (n = 5).