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,).