High sensitivity method for determination of trace curcumin in the aqueous phase

Abstract

A new ionic liquid (IL) based micro-extraction method was developed for the spectrophotometry and spectrofluorometry determination of curcumin in curry products. ILs can effectively extract curcumin from aqueous solution which were used instead of large-scale organic solvents to reduce environmental pollution and production cost. Results show that the fluorescence of curcumin is considerably enhanced in 1-hexyl-3-methylimidazolium hexafluorophosphate ([Hmim][PF6]). Under optimized conditions, the absorbance of curcumin is proportional to the concentration of curcumin in the range of 18.4 ng/mL to 494 ng/mL, and the detection limit is 6.1 ng/mL. In addition, the fluorescence intensity of curcumin is proportional to the concentration of curcumin in the range of 0.050 ng/mL to 120.1 ng/mL, and the detection limit is 0.002 ng/mL. Therefore, an efficient spectrophotometry and spectrofluorometry method for the determination of curcumin was established, and the actual concentration in curry products was satisfactorily determined. The content of curcumin in curry sauce were 14.10±0.40 and 14.32±0.37 mg/g when using the spectrophotometry and spectrofluorometry, the content of curcumin in curry powder were 2.50±1.73 and 2.75±1.40 mg/g when using the spectrophotometry and spectrofluorometry.