Extracted ion chromatograms and MRM transitions ratio monitored for ospA in the serum from Lyme disease patients, collected at the time of 1st visit. Data are presented for the YDLIATVDK (A), EGTVTLSK (B), and GYVLEGTLTAEK (C) peptides. Heavy and light versions of peptides represent QconCAT and endogenous ospA, respectively. Overlaid extracted ion chromatograms and bars for transitions ratio are color-coordinated. For transitions ratio, the most intensive transition was taken as a 100 and intensities of other transitions were plotted as a portion of a 100. Measurements were performed in duplicate for 3 Lyme disease patients with three analytical replicates.