The calibration curves were established from the standards rinacanthin-C, -D and -N at the concentration between 12.6 – 201.0 μg/ml for rhinacanthin-C and 3.1 – 51.0 μg/ml for rinacanthin-D and -N. The linear equations of Y=40.569X+35.263 (r2=1.0000), Y=79.615X–4.168 (r2=1.0000) and Y=112.810X+18.292 (r2=0.9999) correspond to rinacanthin-C, -D and -N, respectively.