A subatmospheric, variable pressure sample delivery chamber, useful as an electrospray ionization device for introducing a sample into a mass spectrometer or as a sample delivery device for delivery of a sample to a collection device at subatmospheric pressures, is disclosed. The sample delivery chamber is configured to maintain an operating pressure between 1 and 750 Torr, preferably between 50 and 700 Torr. The chamber has an inlet port for introduction of a gas and an exit port capable of being coupled either to a sampling orifice for an analytical device, usually a mass spectrometer, or directly to a pump for removal of gas. A sample delivery device extends from outside the chamber into the interior of the chamber. The inlet end of the sample delivery device is capable of receiving a sample and the exit end of the sample delivery device is aligned with the exit port of the chamber, if the sample is to be delivered to an external analytical device, or aligned with the collection device, for direct collection of the sample.