Electron-emission filament cutoff for gas chromatography + mass

Details Electron-emission filament cutoff for gas chromatography + mass Electron-emission filament cutoff for gas chromatography + mass

1987-09-23

1989-02-28

Anderson, Bruce C.

Radiant energy

Ionic separation or analysis

250282, 250423R, 250427, 250288, B01D 5944

Patent

active

048088200

ABSTRACT:
A gas chromatography plus mass spectrometer (GC/MS) system includes a gas chromatograph, a mass spectrometer, and a computer interface to both of them. The mass spectrometer includes an ion source with an electron emission filament which can be damaged if on during the time a solvent peak is eluting from the chromatography. The filament is regulated to provide a constant emission rate by feedback which causes a current source to compensate deviations from a desired emission level. When a solvent peak begins to elute, the concomitant sudden cooling of the filament is sensitively reflected in the feedback to the current source. a comparator AC-coupled to the current source input can be used in shutting off the current source when the emission current abruptly drops. A computer controller can reactivate the filament in response to a decrease in ambient pressure or elapse of a predetermined duration so that component peaks following the solvent peak can be analyzed.

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patent: 4636680 (1987-01-01), Bills
patent: 4714891 (1987-02-01), Morrison
patent: 4721858 (1988-01-01), Buchanan
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