Bilirubin determination in endothelial cells.
Endogenous bilirubin in endothelial cells (Ea.hy926) was identified by HPLC-TLS, HPLC-DAD or UPLC-ESI-MS-MS system. (a) HPLC-TLS chromatogram of bilirubin standard solution containing the three bilirubin isomers (III, IX, XIII - red line) and the endothelial cellular fraction (blue line). (b) HPLC-DAD chromatograms of bilirubin standard (10 nM, red line) and endothelial cellular fraction (blue line). (c) UPLC-ESI-MS chromatogram of analysed endothelial cellular fraction with peaks representing ions with m/z value of 583.3 [M−H+]−. (d) MS spectrum containing ion with m/z value of 583.3 [M−H+]− obtained after UPLC-ESI-MS analyses at retention time of bilirubin standard elution. (e) MS-MS spectrum containing ion with m/z value of 285.1 after UPLC-ESI-MS-MS of bilirubin standard and the sample of endothelial cellular fraction.