An apparatus for multiple nano-spray delivery of a sample to FAIMS analyzer includes a micro-machined ionization source having a plurality of discrete nozzles. At least some of the discrete nozzles of the plurality are aligned one each with an ion inlet of a plurality of discrete ion inlets of the FAIMS, so that ions produced at different discrete nozzles are introduced into different portions of the FAIMS analyzer region. The ions that are introduced via each ion inlet are at least partly separated prior to adding/mixing with the ions introduced via other ion inlets. This reduces the problems of ion-ion electric repulsions that occur when ion density is high.