Principal component and cluster analysis of trace elements in Chinese herb Salvia miltiorrhiza and its relative species

The contents of trace elements, including copper, zinc, iron, magnesium, calcium, chromium, lead, molybdenum, manganese, and cadmium in Chinese traditional herb S. miltiorrhiza and its relative species such as S. miltiorrhiza f. alba, S. evansiana, S. yunnanensis, S. przewalskii, S. cavaleriei, S. cavaleriei var. simplicifolia, S. roborowskii, S. omeiana, S. tricuspis, S. brevilabra and S. cynica were determined by atomic absorption spectroscopy. The principal components analysis of SPSS was applied to the study of characteristic elements in S. miltiorrhiza and its relative species. Three principal components which accounted for 79.3% of total variance were extracted from the original data. The first factor accounted for 49.6% of the total variance, which means that iron, manganese, copper, zinc, cadmium and lead are the characteristic elements in S. miltiorrhiza and its relative species. The results of cluster analysis show that the samples could cluster reasonably into two groups. The samples of S. miltiorrhiza from different regions were classified into one group except S. miltiorrhiza from Zhejiang and S. miltiorrhiza f. alba. The other Salvia species were classified into another group except S. cavaleriei. The S. miltiorrhiza and other Salvia species can be distinguished by this method, whose accuracy of classification is 90%. The cluster analysis based on the contents of trace element in S. miltiorrhiza and its relative species provided a quick, accurate and simple method for authentication of herb Salvia miltiorrhiza.