Artemisia argyi samples were collected from different areas in Hubei Qichun and medicinal botanical garden of Hubei University of Traditional Chinese Medicine, and samples were purchased from different areas in Qichun medicinal market. The same method was used to prepare A. argyi samples from different areas into moxa floss of different leaf velvet ratio. The nitrogen content of A. argyi was determined by Kjeldahl method. The results show that there was an inverse relationship between the content of nitrogen and the level of the leaf velvet ratio grades of moxa floss and nitrogen content. Therefore, six functional models were established to illustrate the relationship between the grades of leaf velvet ratio and nitrogen content. The accuracy of the functional models was evaluated by ■. The cubic function model and exponential function model are selected as the best models and the formula is: Y_(grades)=-4.26 N~3+26.09 N~2-61.09 N+55.84, Y_(grades)=63.68×10~(-1.374N), with R~2 values of 0.976 5 and 0.969 6, respectively. The accuracy reached above 95% of the two function models when verified by laboratory-made moxa floss, while the accuracy of the models was 85.44% when verifed by commercial moxa floss. These results indicate that the model could be applied to the identification of the grades of moxa floss.
Keywords: accuracy; functional model; grade appraisal; leaf velvet ratio; moxa floss; nitrogen.