| 摘要 |
The present invention concerns an improved method and apparatus for analyzing and detecting a charge-neutral sample, which method comprises: (A) conveying a charge-neutral sample as a gas optionally in an inert carrier gas into a radio frequency-only quadrupole wherein said gas sample within said quadrupole is ionized into multiple ions which are focused and dampened by multiple collisions with the carrier gas or a damping gas toward the z-axis of said quadrupole at a pressure of between about 10-1 and about 10-4 torr; and (B) conveying the ionized focussed gas sample through a focusing element into a mass analyzing quadrupole mass spectrometer which is controlled by both radio frequency and DC; and (C) detecting and measuring the level of the multiple ions produced to create a mass spectrum. The present invention also relates to an improved method and apparatus for analyzing a charge-neutral sample, which method comprises: (a) obtaining a charge-neutral sample; (b) evaporating the sample in a gas chromatograph; (c) conveying the evaporated gas sample in an inert carrier gas into a radio-frequency-only quadrupole wherein said gas sample within said quadrupole is ionized into multiple ions which are focused by multiple collisions with the carrier gas at a pressure of between about 10-1 torr and 10-4 torr; (d) conveying the ionized focused gas sample of step (c) through a focusing element into a mass analyzing quadrupole mass spectrometer which is controlled by both radio frequency and DC; and (e) detecting and measuring the level of the multiple ions produced to create a conventional mass spectrum. The present invention produces improved resolution and sensitivity as compared to conventional MS/MS systems. The improved method is less time consuming and costs less than conventional MS/MS systems.
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