to the quantity of ions which can be introduced into the vacuum it can therefore be expedient to use other types of ion introduction for example as shown in fig8 it is possible to use an inlet plate 34 also produced by microsystem engineering which has precisely one small inlet channel for each spray nozzle and guides the ion currents 37 with their sheath gas flows into a first stage of the vacuum system with 36 spray nozzles and hence 36 inlet capillaries with a diameter of around 30 micrometers and a length of 100 micrometers no more gas is introduced into the vacuum than with a conventional inlet capillary the channels can be drilled with laser beams or electron beams or conventional semiconductor machining techniques for example the drilling technique determines the minimum diameter and maximum length the inlet plate 34 here can again be permanently connected to the multi nozzle spray chip via an intermediate insulator 33 so as to be well aligned the low pressure in the first vacuum stage draws in the flows of sheath gas and ions if the total gas flow into this first stage of the vacuum system is small enough a conventional rf ion funnel in this vacuum stage can separate the ions from the gas and transport them to the mass analyzer it.