Ultra high resolution SFC–MS as a high throughput platform for metabolic phenotyping: Application to metabolic profiling of rat and dog bile

Ultra high resolution SFC–MS (on sub-2 μm particles) coupled to mass spectrometry has been evaluated for the metabolic profiling of rat and dog bile. The selectivity of the SFC separation differed from that seen in previous reversed-phase UPLC–MS studies on bile, with the order of elution for analytes such as e.g., the bile acids showing many differences. The chromatography system showed excellent stability, reproducibility and robustness with relative standard deviation of less than 1% for retention time obtained over the course of the analysis. SFC showed excellent chromatographic performance with chromatographic peak widths in the order of 3 s at the base of the peak. The use of supercritical fluid carbon dioxide as a mobile phase solvent also reduced the overall consumption of organic solvent by a factor of 3 and also reduced the overall analysis time by a factor of 30% compared to reversed-phase gradient LC. SFC–MS appear complementary to RPLC for the metabolic profiling of complex samples such as bile.