A simple isocratic HPLC method for the simultaneous determination of curcuminoids in commercial turmeric extracts

Abstract Introduction Turmeric ( Curcuma longa ) extracts contain three curcuminoids (curcumin, desmethoxycurcumin and bisdesmethoxycurcumin) as major bioactive substances. Previously reported HPLC‐UV methods for the determination of curcuminoids have several disadvantages, including unsatisfactory separation times, poor resolution and/or complicated solvent mixtures with gradient elution. Objective To develop a simple isocratic HPLC‐UV method for the simultaneous determination of individual curcuminoids for the quality control of turmeric extracts. Methodology The sample was prepared by dissolving the extract in acetonitrile and subsequently diluting with 50% acetonitrile. This solution was analysed by reverse‐phase chromatography on an Alltima C 18 column with isocratic elution of acetonitrile and 2% v/v acetic acid (40:60, v/v) at a flow rate of 2.0 mL/min, a column temperature of 33°C, and UV detection at 425 nm. The method was validated and applied for quantification of individual curcuminoids in commercial turmeric extracts. Results The method allowed simultaneous determination of curcumin, desmethoxycurcumin and bisdesmethoxycurcumin in the concentration ranges of 10–60, 4–24 and 0.5–3.0 µg/mL, respectively. The limits of detection and quantification were, respectively, 0.90 and 2.73 µg/mL for curcumin, 0.84 and 2.53 µg/mL for desmethoxycurcumin and 0.08 and 0.23 µg/mL for bisdesmethoxycurcumin, and the percentage recoveries were, respectively, 99.16–101.75 (%RSD ≤ 1.11%), 99.50–101.01 (%RSD ≤ 1.74%) and 99.67–101.92 (RSD ≤ 1.31%). Conclusion The method was found to be simple, accurate and precise and is recommended for routine quality control analysis of turmeric extracts containing the three curcuminoid compounds as the main principles in the herb. Copyright © 2009 John Wiley & Sons, Ltd.