Figure 1. Examples of base-peak chromatograms of the clinical groups.

Peptide separation was achieved using a nano-flow reverse-phase HPLC column, with gradient elution ranging from 5 to 55% solvent B in 100 min. P: sites with probing depth >4 mm; G: sites with probing depth ≤3 mm and bleeding on probing; H: sites with probing depth ≤3 mm without bleeding on probing in periodontitis subjects; HH: sites with probing depth ≤3 mm without bleeding on probing in healthy subjects.