A sample plate for mass spectrometric analysis of a specimen is provided comprising
a substrate having an electrically conductive surface, a mask applied to the electrically
conductive surface. The mask is applied to the substrate with a rough surface to
form at least one sample site. The sample site comprises a central portion formed
from the electrically conductive surface and a marginal portion formed from the
mask where the marginal portion is more hydrophobic than the central portion.
