Abstract: Objective: The dual-index sequence analysis method and cluster analysis method were used to compare and analyze the
infrared fingerprints of Periplaneta americana of different manufacturers, and the consistency of the quality of the medicinal materials
was evaluated. Methods: The sample were detected by Fourier infrared spectrometer, and data were analyzed by clustering. At the
same time, two indexes, the common peak ratio and the variation peak ratio, were used to establish different dual-index sequence
analysis methods according to the order of the common peak ratio. Results: The main components of the 20 batches of Periplaneta
americana were not significantly different. The main differences were from the harvest time of the medicinal materials and the breeding
conditions of the plants; and the results of infrared clustering were consistent with the results of the dual-index sequence analysis.
Conclusion: The method has good precision, repeatability and stability. The infrared spectral fingerprint combined with cluster
analysis or dual-index sequence method can quickly and non-destructively evaluate the quality of the Periplaneta americana materials
in different places.

Key words: Periplaneta americana, infrared spectroscopy, cluster analysis, dual-index sequence analysis method