Optimization of the conditions for the analysis of curcumin and a related compound in curcuma longa with mobile-phase composition and column temperature via RP-HPLC

Abstract

To efficiently extract the curcuminoids from turmeric, the extracted samples were simultaneously separated and analyzed via commercial C18 reverse-phase high-performance liquid chromatography using combined water and acetonitrile as the mobile phase in the isocratic elution mode. The experiment results showed that the optimum mobile-phase composition of the water/acetonitrile was 60/40 vol % using the Knauer RP-column. The effect of the solvent composition (methanol in water) on the extraction yield, flow rate (1.0 mL/min), injection volume (10 μL) and column oven temperature (40 C) at a 425 nm wavelength was studied. It was evident that the amount of the curcuminoids that were extracted (extraction time: 4 h) with 100 % MeOH was higher than any aqueous MeOH composition. The correlation coefficients were greater than curcumin (1) 0.9985, demethoxycurcumin (2) 0.9982 and bisdemethoxycurcumin (3) 0.9990 in the regression analyses. The LC-MS data provided molecular weight information for the components in the curcumin standard (purity: 80 %). Thus, the optimum operating conditions were experimentally determined.