English Abstract This report describes the manufacturing, the working
and results of preliminary applications of a home-built electrospray
ionisation source. The source was constructed for a quadrupole
mass-spectrometer (MS) (Finnigan 4000). The elements of the source and
interface are: a micro needle at high potential to the capillary, a
capillary for transport of the ions and a sampling orifice (skimmer) to the
mass analyser and detector. That interface enables the transport of ions
from atmospheric pressure to the required high vacuum in the mass analyser
as well as an appropriate focussing of ions corresponding. The design
concerns the physical dimensions of the different parts and the electrical
potentials. The results show that the electrospray process, the transport
and the focussing operate satisfactorely. The highest sensitivity was
measured for Gramicidin S (polypeptide, MW 1141 Dalton) of about 10
femtomol. For substances with a lower molecular weight the sensitivity was
much lower and ranged from about 100 fmol for the polysaccharide
streptomycin (MW 581 Da) to 50 pmol for polar low MW herbicides glyfosate
and glufosinate. It seems useful to construct an extra focussing device
between the skinner and the analyser to enhance the transmission efficiency
for the low molecular weight species (<400 Da).
