A simple HPLC-fluorescence method for quantitation of curcuminoids and its application to turmeric products.

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-C(18) column (250 x 4.6 mm; i.d., 3 microm) with a mixture of acetate buffer and CH(3)CN. 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.