Create a workflow for untargeted LC-MS/MS metabolomics: (1) biological sample collection (plasma/tissue) with snap freezing, (2) metabolite extraction (80% methanol, -80°C), (3) sample reconstitution and QC pool preparation, (4) UHPLC separation (C18 reverse phase and HILIC), (5) ESI-QTOF mass spectrometry (positive and negative ionization), (6) raw data conversion (MSConvert), (7) peak detection and alignment (XCMS/MZmine), (8) feature filtering and normalization, (9) multivariate statistics (PCA, OPLS-DA, VIP scores), (10) metabolite identification (MS/MS spectral matching against HMDB/METLIN, molecular networking). Show data dimensionality reduction.