PCA of extended glog transformed 2D JRES NMR spectra of fish liver. (A) Scores plot where red circles represent the fish sampled from the River Alde and the blue squares represent fish from the River Tyne. The black line represents the decision boundary between the classes constructed using LDA. (B) Aerial view of the corresponding PC1 loadings plot presented in the format of a 2D JRES spectrum, with J-couplings along one axis to facilitate metabolite identification. (C) Side view of the same loadings plot as in B, highlighting the metabolites that are at higher concentration (red) in fish liver collected from the River Alde.