Fig. 6From: Quartet metabolite reference materials for inter-laboratory proficiency test and data integration of metabolomics profilingConstruction of ratio-based Quartet metabolite reference datasets. a The workflow of integration of ratio-based metabolite reference datasets. b The number of metabolites in high-confidence reference datasets annotated into 10 classes according to the HMDB database. c The distribution histogram of fold changes of the high-confidence reference metabolites for three sample pairsBack to article page