2.5. Metabolomic Data Analysis
Chroma TOF version 4.72 (LECO Corp.) was used for peak extraction, peak alignment, peak deconvolution, and peak identification. Data processing and multivariate analysis were performed using MetaboAnalyst 4.0. Detected metabolic features with missing values greater than 50% were removed, and the remaining missing values were replaced with a limit of detection of 1/5 of the minimum positive value of each variable. Metabolic features were filtered out according to a relative standard deviation of greater than 30% in the QC samples. Filtered metabolic features were normalized by sum, and Pareto scaling was applied for multivariate analysis. Metabolic markers were selected using a 