“…The MS data of each sample consisted of a matrix (ion counts versus mass-to-charge ratio over a range of 120-1500). The massive MS data obtained were handled with PCA (10,(20)(21)(22), placing the classification results on a sound statistical ground. Data of all samples were exported to Excel (Version 2013, 64-bit, Microsoft Corporation, USA) for pre-processing, and were then analyzed by statistical software SIMCA (Version 14.1.0.2047, 64-bit, MKS Umetrics, Umea, Sweden) for PCA and OPLS-DA.…”