荧光光谱技术的交趾黄檀和奥氏黄檀树种识别新方法

New Method for Identification of Dalbergia Cochinchinensis Pierre and Dalbergia Oliveri Prain by Fluorescence Spectroscopy

自然界植物物种中存在小分子有机化合物的荧光特征信息用于识别其身份具有潜在的应用价值。目前,基于木材解剖学特征的交趾黄檀和奥氏黄檀木材树种鉴定存在一定的局限性。该研究从荧光特征出发探索两个红木树种的识别新方法。分别对5组交趾黄檀和5组奥氏黄檀木材样品中的荧光物质进行完整提取,通过荧光照片、二维荧光谱图、三维荧光谱图对两个红木样品存在的荧光物质种类和数量进行了确认。荧光照片结果显示交趾黄檀和奥氏黄檀均呈现明显的荧光特征且随着存贮时间的变化荧光物质能够稳定存在;二维荧光谱图和三维荧光谱图更加详细地展示了两个树种各自的荧光特征,结果显示交趾黄檀提取液含有一种荧光物质,该物质的最大激发波长为297nm,最大荧光发射波长为327nm;奥氏黄檀提取液的荧光谱图呈现两个最大激发和两个最大发射,最大激发波长分别为317和333nm,最大荧光发射波长分别为342和358nm,表明奥氏黄檀提取液中包含两种荧光物质或者存在一种含两种荧光团的荧光物质。另外,不同来源的两个红木试样存在的荧光物质数量和特征各自具有明显的一致性,且两种树种之间存在明显的区别,表明荧光特征能够用于它们身份的识别。此外,该研究构建了交趾黄檀和奥氏黄檀两个红木树种的荧光物质提取方法,交趾黄檀荧光物质的最佳提取试剂为乙腈,体积比为10∶1的乙酸乙酯和乙腈混合试剂更加适用于奥氏黄檀,且两种荧光物质的提取均在12h内达到稳定。研究结果表明荧光光谱技术能够用于交趾黄檀和奥氏黄檀的识别与鉴定,该方法在红木树种的鉴定具有十分重要的应用价值。

The fluorescence characteristic of small molecular organic compound in nature has potential application value for plant species identification. At present, the identification of two species about Dalbergia cochinchinensis Pierre and Dalbergia oliveri Prain based on the anatomical characteristics of wood has its limitation. So, we explored a new method for identification of Dalbergia cochinchinensis Pierre and Dalbergia oliveri Prain by fluorescence spectroscopy in the paper. The fluorescent substances were completely extracted in five different wood samples of Dalbergia cochinchinensis Pierre and Dalbergia oliveri Prain. Fluorescence photos, two-dimensional and three-dimensional fluorescence spectrum were used to confirm the species and quantity of fluorescent substances in wood samples of the two species. The results of fluorescence photograph shown that the extract solutions of Dalbergia cochinchinensis Pierre and Dalbergia oliveri Prain both present obvious fluorescence characteristics and the fluorescence substances are stable in two years of storage. Two-dimensional and three-dimensional fluorescence spectrum exhibit the fluorescence characteristics of the two species in more detail. The results indicate that there is a fluorescent substance in the extract solution of Dalbergia cochinchinensis Pierre, and the maximum excitation and emission wavelength of the fluorescence substance are 297 and 327 nm, respectively. However, the fluorescence spectrum of extract solution from Dalbergia oliveri Prain present two maximal excitation and emission wavelengths respectively, the maximum excitation is 317 and 333 nm, and the maximum emission is 342 and 358 nm, which indicates that there are two kinds of fluorescent substances or one kind of fluorescence substance containing two groups of fluorescence. The respective quantity and characteristics of fluorescent substances of the two species are obviously accordant, and there are obvious differences between the two species, which can be used to confirm their identities. Moreover, the extracting methods of fluorescent substances from the wood sample of the two species are built in this paper. Acetonitrile is an optimal reagent for the extraction of fluorescent substance in the wood sample of Dalbergia cochinchinensis Pierre, and the mixed reagent prepared according to the volume ratio of ethyl acetate and acetonitrile equals 10∶1 is more suitable for that of fluorescent substance in Dalbergia oliveri Prain. The extraction of fluorescent substance is beginning to level off within 12 hours for the wood samples of Dalbergia cochinchinensis Pierre and Dalbergia oliveri Prain. The results indicate that the fluorescence spectroscopy technique can be used to identify Dalbergia cochinchinensis Pierre and Dalbergia oliveri Prain. The method will be of very important value to the identification of rosewood species.