[Fast and nondestructive discrimination of donkeyhide glue by near-infrared spectroscopy]

Near-infrared (NIR) diffuse reflectance spectroscopy and pattern recognition techniques were applied to develop a fast identification method of a Chinese patent medicine-donkeyhide glue. Samples from different manufactures (eight genuine samples and six counterfeits) were collected, and their NIR spectra were obtained. NIR spectra were pretreated with multiplicative signal correction (MSC) and wavelet transformation to diminish baseline offset. Similarity and Mahalanobis distance methods were separatemy used to qualify donkeyhide glue. For the similarity calculation, spectra of the two real ones were selected as standards, and then others were compared with the standards to obtain the match value. All the samples were rescanned once for the Mahalanobis distance methods, and totally twenty eight spectra were separated into three sets for cross-validation. The two methods can both distinguish the counterfeits of donkeyhide glue successfully. The proposed method is accurate and robust, and could be used in the discrimination of other traditional Chinese medicines.