## 3 Identification of Chinese Medicinal Materials
### Species Identification  
In 2004, [PERSON] et al. [35] reported the first study of using electrochemical oscillation for TCMs identification. KBrO\({}_{3}\)-MnSO\({}_{4}\)-H\({}_{2}\)SO\({}_{4}\) and acetone have been used for construction of an oscillating system. The fingerprints of 30 species of TCMs were reported. The fingerprints of every species have significant differences, which indicated that they can be used for identification. During the following years, the fingerprints of hundreds of TCMs have been reported [36, 37, 38, 39, 40]. At the same time, the optimization of the technology system and improvement of data statistics were carried on. Factors such as temperatures, sample dosage, reaction systems and stirring speed were taken into consideration [41]. The method of similarity calculation was applied for data analysis [42].  
[PERSON] et al. [43] recorded the fingerprints of nine species of TCMs, among which some of them have similar functions. By comparing fingerprints, they found that even if the same types of herbal medicines contain the same chemical components, their fingerprints are quite different, which can be used for their identification. A similar study was reported by [PERSON] et al. [44]. They obtained the fingerprints of seven species (five families) on the basis of an oscillation behavior mechanism. Traditionally, TCMs are often taken from a certain organ of plants. [PERSON] et al. [45] investigated fingerprints of different organs of the same TCMs using H\({}^{+}\)-Mn\({}^{2+}\)CH\({}_{3}\)COOCH-BrO\({}_{3}\)\({}^{-}\) as the reaction system. The results indicated that the fingerprints of different organs had significant differences. This study demonstrates that the electrochemical oscillation technique is not only applicable to species identification but, in some cases, can also be used for the identification of different plant organs. In 2018, [PERSON] et al. [46] reported fingerprints of 30 species using KBrO\({}_{3}\)-CeSO\({}_{4}\)  
Figure 1: Schematic diagram of typical electrochemical oscillation fingerprints.  
H\({}_{2}\)SO\({}_{4}\)-malonic acid-tartaric acid as the reaction system. The results showed that not only fingerprint shapes but also induction time, maximum amplitude and oscillation period were also significantly different [47; 48; 49]. These indicators can be also used for discrimination. A similar study was reported by [PERSON] et al. [50]. They distinguished four TCMs in Zingiberaceae using KBrO\({}_{3}\)-MnSO\({}_{4}\)-H\({}_{2}\)SO\({}_{4}\)-malonic acid as the mixed oscillation system. In addition, Astragali Radix (_Astragalus membranancceus_ var. _mongholicus_ or _A. membranancceus_); Cassiae Semen (_Cassia obtusifolia_ or _Cassia tora_); Puerariae Lobatae Radix (_Pueraria lobata_); Radix Sophorae Flavescentis (_Sophora flavescens_); Glycyrrhizae Radix (_Glycyrrhizae uralensis_, _Glycyrrhiza inflata_ or _Glycyrrhiza glabra_); Coptidis Rhiza (_Coptis chinensis_, _Coptis deltoidea_ or _Coptis teeta_), Pulsatillae Radix (_Pulsatilla chinensis_) [51]; Polygoni Cuspidati Rhiza Et Radix (_Reynoutria japonica_) and Polygoni Multiflori Radix (_Polygonum multiformu_) [52]; Rhei Radix et Rhiza (_Rheum officinal_) [51]; and four species in _Fritillaria_ L. [53] were identified by different studies.