Fig. 11 The reduced quality of the ion map with increasing
number of matrix layers without and with normalization (TIC – total ion
current and RMS - root mean squared) – negative ionization mode (9AA 7
mg/ml 70% EtOH).
Norharmane (6 mg/ml matrix
(chloroform:MeOH:H2O)) – negative ionization mode
In the case of norharmane (6 mg/ml in
chloroform:MeOH:H2O, 1:1:1, v/v/v solution) the
intensity of the peaks on the spectrum increased with the number of the
matrix layers but starting from the 12 layers, further increase was
minor. Conversely, the s/n ratio decreases starting from the twelfth
layer. Thus, up to 12 matrix layers seem to be optimal. For the spraying
nozzle position, 15 mm is performing the best since the intensity, and
s/n ratio is relatively high. Lower nozzle position does not change the
intensity but might be responsible for the molecule’s delocalization
(see: Fig 12, 13).