Patent ID: 8796616

Claim:
A miniature mass spectrometer system comprising a plurality of vacuum chambers, the system further comprising: a. an ion source operating substantially at atmospheric pressure and employing electrospray ionisation, microspray ionisation, nanospray ionisation, chemical ionisation, or derivatives thereof; b. an rf ion guide provided within an ion guide vacuum chamber of the system, the ion guide defining a ion path between an entrance and exit to the ion guide vacuum chamber, the dimensions and geometry of the ion guide being such that apertures through which gas may escape from the ion guide have a total area less than 10 cm 2 ; and c. a mass analyser provided within a mass analyser vacuum chamber of the system; wherein the vacuum chambers containing the rf ion guide and the mass analyser are operably pumped at a pressure lower than about 5×10 −2 Torr, other vacuum chambers of the system, where provided, being operably pumped at a pressure higher than about 50 Torr.