torr pressure when the droplets are large the gas flow is sufficient to transport the droplets away from the orifice against the attractive force of an electric field existing between the source 10 and the entrance orifice 12 droplets that are very small are evaporated by heated gas to produce charged sample ions that are easily attracted by the electric field to the entrance orifice and through capillary 16 to vacuum chamber 14 ions move through a skimmer 18 into a hexapole ion guide 20 within a second chamber 17 at 8 mtorr ion guide 20 directs the ions to an ion guide exit 22 and to an ion guide focus lens 24 and deflector lens 26 to an aperture in end cap 28 of the ion trap 30 ions from ion trap 30 are subsequently detected by a detector 32 which along with vacuum chamber 33 is maintained at 30 u03bctorr pressure a hyperbolic ring 34 of the ion trap is energized by a 760 khz rf source 36 and the vacuum within the mass spectrometer is maintained by pumps 38 and a foreline pump not shown as is conventional an inert gas atmosphere such as helium is provided in the ion trap 30 by helium flow controller 40 fig2 is a view of hexapole ion guide 20 which receives ion beam 44 through skimmer 18 and directs the ion beam through ion guide exit 22 and ion guide focus lens 24 to deflector lens.