Analysis of curcumin and piperine in biological samples by reversed-phase liquid chromatography with multi-wavelength detection

•A reversed-phase HPLC method was developed to analyze both curcumin and piperine.•Emodin was the internal standard, and multi-wavelength detection was employed.•Baseline resolution of curcumin, piperine and emodin was obtained in less than 4 min.•The detection limits were in the low ng/mL range for curcumin and piperine.•This method has been used in various samples, such as human serum and cell lysates.