Determination of catechin in lotus rhizomes by high-performance liquid chromatography.

A novel method was developed to analyze lotus rhizome polyphenolic catechin using high-performance liquid chromatography (HPLC). The retain time of catechin was 14.72 min under the optimized condition. Mass spectrometry was further employed to qualify and quantify the purity of the catechin peak. Good linearity (R=0.9997) was obtained within the range of 50-1,000 ng. The coefficient of variance was determined as 5.2%, with a recovery rate of 97%. The detection and quantification limitations of catechin were 23 ng and 50 ng, respectively. The catechin level was 0.0025% in the lotus rhizome, and 0.011% in the knot of the lotus rhizome (Nelumbo nucifera cv. 'damao jie'). The optimized conditions of HPLC for catechin detection in the lotus rhizome matrix were as follows: the SuperlcosIL™ LC-18 analytical column (150 mm×4.6 mm, 5 µm), methanol-water-acetic acid (10:90:1, volume ratio) as the mobile phase, an UV detector at 280 nm, a flow rate of 0.8 ml/min, column temperature at 30°C, and an injection volume of 10 µl.