New sample supply technique for field desorption mass spectrometry

A new sample-loading technique is described for emitters covered with microneedles as used in field desorption mass spectrometry. An increase in ion sensitivity of about two orders of magnitude over the standard syringe technique can be obtained with tne new method. It consists essentially in loading the sample only on to a small portion of the needles in front of the counter electrode opposite the field anode.