Fig. 2 Blurring effect after tissue washing - the difference between white and gray matter has vanished. Washing: 50 mM ammonium acetate for 10 s, matrix: 25 mg/ml DHB (MetOH:H2O 1:1, 0,2% TFA), m/z 718.
The number of matrix layers and the height of the spraying nozzle during matrix application – positive ionization mode (DHB, norharmane, and DAN matrices)
To compare the influence of the different matrix layers and the position of the spraying nozzle on the spectra quality, we decided to select two parameters: the peak intensity (int.) and the signal-to-noise ratio (s/n). Peak intensity alone could be misleading since the increase of the overall spectra intensity may occur simultaneously with the background signal increase, which could, in turn, decrease the s/n value and, in effect, worsen the analysis quality.
25 mg/ml DHB matrix (MeOH:H2O 1:1, 0.2% TFA) – positive ionization mode
25 mg/ml DHB matrix (50% MeOH, 0.2% TFA) could be treated as a reference matrix in the positive ionization mode. To check the influence of the parameters of matrix application by the SunCollect® system, we have chosen four different numbers of matrix layers (L= 8, 10, 12, 14) and four different heights of the spraying nozzle (Z=25, 15, 5, 1,).