Analytical Sciences

A Simple HPLC-fluorescence Method for Quantitation of Curcuminoids and Its Application to Turmeric Products

Junwei ZHANG,* Sakie JINNAI,* Rie IKEDA,* Mitsuhiro WADA,* Shinjiro HAYASHIDA,** and Kenichiro NAKASHIMA*

*Department of Clinical Pharmacy, Graduate School of Biomedical Sciences, Nagasaki University, 1-14 Bunkyo-machi, Nagasaki 852-8521, Japan
**Choko Shoyu Miso Corporation, 815 Mizooka-machi, Nagasaki 856-0844, Japan

An HPLC method using fluorescence detection for the quantitation of curcuminoids, such as curcumin (C), demethoxycurcumin (DMC), and bisdemethoxycurcumin (BDMC) in turmeric products is described. This method involves a simple ultrasonic extraction with methanol as a pretreatment of turmeric products. The separation of curcuminoids and 2,5-xylenol (internal standard) was achieved within 30 min on a Cadenza CD-C₁₈ column (250 × 4.6 mm; i.d., 3 µm) with a mixture of acetate buffer and CH₃CN. The calibration curves of standard curcuminoids showed good linearities of more than 0.993 of the correlation coefficient. The instrumental detection limits for C, DMC and BDMC (signal-to-noise ratio = 3) were 1.5, 0.9 and 0.09 ng mL^-1, respectively. The relative standard deviations of intra-and inter-day assays by curcuminoids spiked to turmeric powder were less than 6.1%. The proposed method was successfully applied to determine curcuminoids in commercial turmeric products, such as turmeric powders, a tablet, a dressing, a beverage, tea, and crude drugs.

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