Identification of Agarwood and Agarwood Imitations by Three-Dimensional Fluorescence Spectra and Electronic Nose

Agarwood is a natural combination of resin and plant wood. Since its unique fragrance and gentle-feeling appearance, it is often made into jewelry crafts such as bracelets or carvings. The production of agarwood is scarce and the price is high.The market is flooded with imitations of agarwood made from wood soaked in the essence, whose appearance and smell are hardly distinguishable from natural agarwood. Therefore, it is very important to identify the natural and imitated agarwood. The components and contents of organic matter in the oil of agarwood and its imitations are different, so they have different fluorescence characteristics.In this paper, 14 batches (45 pieces) of natural agarwood and 9 batches (6 bead bracelets and 3 pieces) of agarwood imitations were collected from domestic and foreign markets, and their three-dimensional fluorescence spectra were measured, and 14 batches of natural agarwood and 4 batches of agarwood imitation products were analyzed by electronic nose test. The results showed that natural agarwood had the same three-dimensional fluorescence spectrum characteristics, with a drum shaped fluorescence peak, and the fluorescence peak areas were in the same region λ_Em=390-600 nm/ λ_Ex = 300-500 nm, the strongest area was near λ_Em=470 nm, λ _Ex = 385 nm.According to the characteristics of fluorescence, the agarwood imitation can be divided into three types: the first type of imitation had no characteristic fluorescence; The second type had multiple fluorescence peaks, except the strongest peak λ_Em=470, λ_Ex=400 nm, there were other fluorescence peaks; The third type had a similar fluorescence with agarwood, with a fluorescence peak, and the peak area was in the range of λ_Em=380-600 nm/ λ_Ex = 300-550 nm, the strongest area was near λ _Em=470 nm, λ _Ex = 400 nm. Electronic nose test data was analyzed by SPSS for Fisher discriminant analysis(FDA), it could accurately distinguish between natural and imitated agarwood. Using 3D fluorescence features to identify the first and second types fluorescent imitations, and using electronic nose to identify the third type fluorescent imitation, can quickly identify the authenticity of agarwood.