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. Author manuscript; available in PMC: 2013 Dec 1.
Published in final edited form as: J Am Soc Mass Spectrom. 2012 Sep 25;23(12):2075–2082. doi: 10.1007/s13361-012-0482-z

Figure 4. De novo calibration is robust to a reduction in signal.

Figure 4

Mass measurement error heatmaps were generated using all 6,628 significant peptide spectrum matches in the LTQ-Orbitrap-Velos data as described in Figure 3 and Materials & Methods. A), C), and E) depict the systematic mass measurement error detected by FineTune using 25%, 10%, and 1% of the (44,944) MS/MS spectra from the original file, respectively; B), D), and F) depict the mass measurement error after correcting for the systematic mass measurement error detected in figures A), C), and E) respectively. G) shows the median mass measurement error from the 6,628 PSMs with no calibration and after calibration by FineTune with varying percentages of the original spectra as input. The whiskers are 1.5 times the inner quartile.