Abstract: A rapid and nondestructive method using nearinfrared diffuse reflectance spectroscopy was presented to determine the principal components (osthol and imperatorin) of Cnidium monieri  extracted by supercritical carbon dioxide. Partial least squares (PLS) method was utilized to establish the calibration models for describing the relationship between the nearinfrared spectral information and each component with high performance liquid chromatography (HPLC) as a reference method. The effects of the region sele ction of wavelength and the numbers of principal components on the prediction ab ility of PLS were discussed and the concentrations of the samples of the prediction set were predicted, the predicted results were reliable.

Key words: nearinfrared diffuse reflectance spectrum, partial least squares, C nidium monieri, extraction of supercritical carbon dioxide 