The present invention provides an apparatus and method for use with a mass spectrometry system. The invention provides an ion source for providing radiative heating to an ionization region. The ion source includes a nanospray ionization device for producing ions and a conduit adjacent to the ionization device for receiving ions from the ionization device. The conduit includes a conductive material for providing indirect radiative heating to the ionization region. Direct radiative heating may also be provided using a heater in the conduit. The ion source may be used separately or in conjunction with the mass spectrometry system. When used in conjunction with a mass spectrometry system a detector may also be employed down stream from the device. A method for desolvating an analyte using the device is also disclosed.