Fig. 2.

Examples of the UPLC chromatograms. A, Chromatograms showing separation of the INT-PYD, PYD, DPD, and PEN standards (first three panels) and detection of PYD, DPD, and PEN in the HCl-hydrolyzed random laser-microdissected bone tissue (Sample). The identified cross-links are described directly in the figure. B, Chromatograms demonstrating separation of the derivatized hydroxyproline (ProOH) and internal standard (INT-Std) from ProOH solutions, BioRad calibrator and LCM dissected bone tissue using the same column as for the separation of the three collagen crosslinks but different separation conditions.