Figure 2
Results of measurements of the amino acids methionine (left) and histidine (right). (A) Measured signal intensities of mass 56 and 61 of methionine and 109 and 110 of histidine, at each of the forty positions per scan. Empty positions have signals below a signal-to-noise ratio of six, which are omitted. (B) Ratios between the corresponding mass fragments at each of the forty positions. The solid line indicates the mean ratio from the co-added data of all positions. The dashed lines give the 1σ standard deviation of the mean of the measured data. (C) Intensities measured as a function of average surface concentration for concentrations in the range of 0.14–14 pmol mm−2 (1–100 µM solution concentration), including linear regression coefficients. (D) Synthetic mass spectra (blue) compared to the measured data (black).
