Application of ultra performance liquid chromatography-mass spectrometry to profiling rat and dog bile

Reversed-phase gradient UPLC-ESI-MS, in both positive and negative ionization modes, has been applied to the analysis of untreated bile obtained from bile-cannulated rats and dogs. The use of UPLC provided a high-resolution system that enabled global metabolite profiles of bile from the two species to be obtained that were suitable for metabolomic and metabonomic applications. When these metabolite profiles were analyzed using unsupervised multivariate statistical methods, based on principle components analysis (PCA), they were correctly classified by species of origin. Conventional approaches to characterizing sample components via, for example, mass and retention time compared to authentic standards resulted in the identification of a range of bile acids. In addition, the value of using an "MSE" approach to simplify the problem of classifying and identifying the metabolites present in the sample (as e.g., sulfates or taurine conjugates) was demonstrated.