Transformed and filtered metabolite abundances

Metabolites with RSD < 30% in pooled QCs were removed, yielding 365 metabolites in positive mode and 414 in negative mode. Metabolite intensities were normalized by sample weight and total ion count, and signal drift corrected with QC-RSC. Missing values were imputed with half-minimum values, and intensities were log2-transformed and auto-scaled before merging positive and negative datasets. Duplicate metabolites were removed using a workflow described in the publication.