Differential mobility spectrometry/mass spectrometry: The design of a new mass spectrometer for real-time chemical analysis in the field

Abstract The design of a prototype, field-portable mass spectrometer (MS) is described. The MS has been designed with an atmospheric interface in order to couple the system to a commercially available differential mobility spectrometer. The differential mobility spectrometer provides selective injection of trace-level analytes of interest into the inlet of the MS for real-time chemical detection. To accomplish this task, the MS design incorporates the use of an electrodynamic ion funnel to transport the ion beam, generated at atmospheric pressure, to the high-vacuum chamber that houses the mass analyzer. This leads to a design that utilizes two stages of differential pumping to achieve an overall pressure drop from atmosphere (760 Torr) to approximately 1 × 10 −5  Torr. A mass resolution of 140 ( m / z  = 84) and a limit of detection of approximately 1 ppb v have been measured for the system.