Examples of UPLC chromatograms.

<p><b>A</b>. Identification of PEN (shown by red arrow) in the glucosylated human cortical bone samples. <b>B</b>. Identification of PEN (shown by red arrow) in the ribosylated human cortical bone samples. <b>C</b>. The UPLC chromatogram with the peak of ProOH (shown by red arrow) used for determination of collagen contents. Similar amounts of the samples were injected to the column. Notably, the chromatogram obtained from the analysis of the ribosylated sample contains several peaks that are not present in the glucosylated sample.