Abstract：The trade of elephant ivory (from now on referred to as ivory) and its products has been completely banned in China, but the smuggling has not stopped. The identification of ivory is an important part of the fight against smuggling. The ivory objects can be identified visually if characteristic features, such as the Schreger pattern, on the cross-sections can be observed. However, if it does not have the features or disappears after carving, the sample is difficult to identify by morphology. When the morphological method is not adequate, molecular biology-based method is an alternative. However, since the extremely low DNA content, extracting DNA from ivory is not easy. Some scholars have distinguished ivory and the analogues (teeth of other animals) by using the Raman spectrum and the short wave region（780~1 100 nm）of the near-infrared (NIR) spectrum. In this study, an identification method of ivory was established by establishing a NIR spectroscopy identification model, based on the spectrum region from 1 000 to 1 800 nm. Taking African elephant (Loxodonta spp.) ivory, Asian elephant (Elephas maximus) ivory and mammoth (Mammuthus spp.) ivory as the calibration set and other non-ivory products, including sperm whale (Physeter macrocephalus) teeth, hippopotamus (Hippopotamus amphibius) teeth, taguanut (phyelephas macrocarpa), ivory plastic imitation, etc. as the verification set, a total of 383 NIR spectra of 230 samples were collected. By comparing the spectral data of ivory products with different colors and thicknesses, it was found that the color and thickness of the ivory will affect the analysis results. Scanning the parts with typical color of the substance and the parts with the thickness greater than 1 mm is recommended. Based on the spectra in the regions of 1 160~1 200, 1 430~1 500, 1 680~1 710 and 1 720~1 750 nm, and the SIMCA (soft independent modeling by class analogy) qualitative analysis method, a calibration model for predicting ivory or non-ivory by NIR spectroscopy was developed. After balancing the false positive rate and false negative rate, it was deduced that the best principal factor of this model was 2 and the F value was 0.21. When applying the model, the recognition accuracy of ivory was 100%; all the animal horn, plastic and ivory fruit products could be accurately identified as non-ivory with 100% accuracy. However, the teeth of other animals with similar ivory textures, such as boar teeth and sperm whale teeth, tended to be mistaken for ivory by the model; consequently, further testing by other methods was required for these substances. The spectral model method is simple, nondestructive, and more objective and efficient than manual interpretation of spectrograms. Therefore, it is suitable to be used as a preliminary screening method for on-site law enforcement by regulators.
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