On-Site Analysis and Rapid Authentication of Valuable Agarwood Samples by Paper Capillary Spray Miniature Mass Spectrometry

Agarwood is a resinous wood produced by plants of the genus Aquilaria in the Thymelaeaceae family after being injured. The wide distribution of origins and the complexity of formation have led to various species of agarwood. The preciousness, universality of application and scarcity of resources bring difficulties to the quality control of agarwood, the in-situ ionization technique shows great potential in the rapid and accurate identification of valuable herbal medicines. In this paper, base on the combination of paper capillary spray and miniature mass spectrometry, different kinds of agarwood and counterfeits were directly added onto the chromatography paper, the active ingredients were extracted by solvent and then carried out by the portable miniature mass spectrometry, which could be implemented to perform an effective and on-site analysis, and the whole process only took about 1 min. Characteristic highly oxidized 2-(2-phenylethyl)chromones and flindersia-type 2-(2-phenylethyl)chromones were detected in authentic agarwood, and other characteristic flindersia-type 2-(2-phenylethyl) chromones were detected in authentic Kynam agarwood (special variety of agarwood), while the above characteristic components were not detected in counterfeits. Furthermore, an artificial intelligence model based on random forest algorithm was established for automatic identification. This approach is versatile, unfettered by location or environmental constraints, making it particularly valuable in the identification of precious Chinese herbal medicines.

This study introduces a streamlined agarwood identification method utilizing PCS-mini MS, which merges ambient ionization with miniature mass spectrometry. This method boasts rapid, efficient, and environmentally friendly characteristics. It requires only a small sample quantity and straightforward sample handling to facilitate real-time detection of agarwood’s characteristic components. PCS-mini MS can effectively identify characteristic 2-(2-phenylethyl)chromones in agarwood, distinguishing authentic agarwood and Kynam agarwood samples from counterfeit products by their specific chromone profiles. Furthermore, the application of a machine learning method based on random forest algorithm enables quick and accurate differentiation of various agarwood types. In summary, this study provides a reliable tool for the authentication of agarwood and expands the applicability of PCS-mini MS, showing promising potential for on-site and rapid testing of natural samples.