The present invention is a device to restrict the sampling of analyte ions
and neutral molecules from surfaces with mass spectrometry and thereby
sample from a defined area or volume. In various embodiments of the
present invention, a tube is used to sample ions formed with a defined
spatial resolution from desorption ionization at or near atmospheric
pressures. In an embodiment of the present invention, electrostatic
fields are used to direct ions to either individual tubes or a plurality
of tubes positioned in close proximity to the surface of the sample being
analyzed. In an embodiment of the present invention, wide diameter
sampling tubes can be used in combination with a vacuum inlet to draw
ions and neutrals into the spectrometer for analysis. In an embodiment of
the present invention, wide diameter sampling tubes in combination with
electrostatic fields improve the efficiency of ion collection.