A robust RP-HPLC method for determination of turmeric adulteration

Abstract

A gradient reverse phase high pressure liquid chromatographic method has been proposed for simultaneous determination and separation of curcumin (CUR), bisdemethoxycurcumin (BMC), demethoxycurcumin (DMC), and metanil yellow (MET). The separation was achieved on an Agilent Eclipse XDB-C18 (4.6 mm × 150 mm, 3.5 µm) analytical column using photodiode array (PDA) detection at 425 nm. Gradient elution of solvent A (mixture of 0.1% trifluoro acetic acid and 0.1% formic acid 50:50 v/v) and solvent B (acetonitrile) at a flow rate of 0.8 mL/min was used to accomplish adequate separation of the analytes. The developed method was extensively validated with respect to linearity, detection and quantitation limits, precision, recovery, and robustness testing. Method variables, viz., mobile phase flow rate (0.90 ± 0.05 mL/min), percentage of B at start of gradient (40 ± 2%) and detection wavelength (425 ± 5 nm) were studied by a Box–Behnken Design (BBD) for testing the robustness of the proposed method. The method was found robust, with no significant variations in the method performance, linear in the range of 10–80 µg/mL (r2 = 0.999) and precise (RSD ˂ 2%) satisfying regulatory criteria. The method is selective for rapid determination of turmeric adulteration with a detection limit of 0.37–2.48 µg/mL.