Barringer Research Limited

Robert H Prince

The present invention relates to an atmospheric pressure quadrupole mobility spectrometer for detecting and identifying trace amounts of various molecular species present in a gas. The invention includes an outer housing comprising forward and rear sections which define forward and rear chambers. The gas under analysis is caused to flow into the inlet part of the forward section where ionizers mounted around the circumference of the forward chamber convert a portion of the molecular species present in the gas into stable molecular ions suitable for analysis. Towards the center portion of the forward chamber a carrier gas is mixed with gas and ions so formed. Four parallel, cylindrical electrodes symmetrically positioned about the longitudinal axis of the rear chamber are connected in opposing pairs to a bipolar power supply which supplies a predetermined repetitive voltage waveform to the electrodes thereby creating a generally hyperbolic electric field between the electrodes. The gas under analysis containing the molecular ions and the carrier gas flow between the electrodes where the molecular ions interact with the electric field. The electric field is such that only molecular ions of the predetermined 'mobility' will undergo stable trajectories through the electric field and emerge to strike a detector located adjacent to the outlet side of the rear chamber. All other molecular ions undergo unstable trajectories as they pass through the electric field and eventually strike one or other of the electrodes and are discharged before reaching the detector.

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Unionville, Canada

Robert H Prince