System for measuring and recording gas chromatograms and mass spectra by a direct combination of a gas chromatograph and a quadrupole mass spectrometer

Claim 3

A system as described in claim 1, wherein the said third means controls said generator means to provide said radio-frequency voltage components of increasing absolute peak values and D.C. voltage components of increasing absolute values during each said short period, and maintains said constant ratio of the D.C. to peak A.C. values.

Claim 4

A system as described in claim 2 including an oscilloscope for observing the output of the quadrupole spectrometer, and relay means effective at one setting, for producing a chromatogram to actuate said first means to reduce the D.C. voltage components to null and to activate the said second means to supply the quadrupole with radio-frequency voltage of said constant peak value, and at a second setting, for actuating said third means for changing the voltages applied to the quadrupole for carrying out a single scan of a mass spectrum, push-button activated timer means actuating said relay means from said first setting to said second setting for a preselected short duration, whereby said second setting may be accomplished by push button operation upon the occurrence of a gas chromatogram peak.

Claim 5

A system as described in claim 1 comprising: a radio-frequency A.C. generator and a D.C. generator as said voltage generator means, said radio-frequency A.C. generator generating a fixed frequency and including two self-oscillators in push-pull arrangement jointly controlled, driven by a first D.C. amplifier establishing the r.f. amplitude proportional to voltage of the D.C. amplifier input, and having respective outputs applied as said A.C. components to the respective pairs of opposed poles of the said quadrupole and also to a radio-frequency rectifier with output providing feedback to said D.C. amplifier for stabilizing the amplitude of the radio-frequency generator and also providing the hereinafter-named common D.C. input, said D.C. generator comprising two D.C. amplifiers providing equal D.C. outputs of opposite polarities as said D.C. components fed through radio-frequency filter means to respective pairs of said poles, said D.C. outputs proportional to said common D.C. input applied to said two D.C. amplifiers, thereby to establish said constant ratio of D.C. to peak A.C. values, a saw tooth generator, a comparator for applying a differential voltage, derived from a D.C. reference voltage and the output of the saw tooth generator as the input of the first D.C. amplifier, whereby the A.C. generator is driven to produce, in the course of each saw tooth cycle, outputs of increasing peak value of amplitude, grounding means actuatable for grounding the outputs of said two D.C. amplifiers as said means to reduce the said D.C. components to null, first and second D.C. reference voltage sources, and relay means effective on a first relay setting and ineffective at a second setting to deactivate the saw tooth generator, to apply the first D.C. reference voltage source to said comparator thereby to cause said A.C. generator to produce said voltages of a constant peak value, and to actuate said grounding means to ground the D.C. outputs, whereby at the first setting the system is enabled for gas chromatogram production, on said second setting is effective to apply said second reference voltage source to said comparator in conjunction with said saw tooth output thereby to cause said A.C. generator to produce r.f. outputs with increasing peak voltages, and to deactivate said grounding means, whereby at said second setting the system is enabled for a mass spectrum scan.

Claim 6

A system as described in claim 4, including first potentiometer Means through which said common D.C. input is applied from said rectifier to said two D.C. amplifiers thereby to select said constant ratio of D.C. to peak A.C. values; and second potentiometer means included in the first said reference voltage source to establish the reference voltage applied to said comparator during the said first setting of the relay means, whereby said constant absolute peak value of said radio-frequency voltages is selectable.

Claim 7

A system as described in claim 4, wherein said mass spectrometer includes means producing a spectrometer output signal proportional to gas ions passing through said quadrupoles, said system further comprising a gas chromatogram recording pen recorder and a signal holding circuit therefor, and a mass spectrum recording photochart recorder; said relay means further effective on said first setting, to apply said spectrometer output signal through the signal holding circuit to said pen recorder, and on said second setting to apply said spectrometer output signal to said photochart recorder and simultaneously to activate a chart drive thereof.

Claim 8

A system as described in claim 6 including pushbutton activated timer means actuating said relay means from said first setting to said second setting for a pre-selected said short duration and thereafter restoring said first setting whereby said second setting may be attained by push button operation upon observed occurrence of a gas chromatogram peak.

Claim 9

A system as described in claim 7, further including an oscilloscope to which the said spectrometer output signal is applied as the vertical input and the output of said saw tooth generator is also applied, as the horizontal input, whereby mass spectra may be displayed on the oscilloscope.

Claim 10

A system as described in claim 7, wherein said means producing the spectrometer output signal includes an adjustable gain electrometer providing said output signal, an electron multiplier for enhancing the ion current arising in an ion collector for the quadrupole and providing an input to the electrometer, and means rendered effective upon said first setting of said relay means to decrease the gain of said electrometer.

Claim 11

A system as described in claim 8, including third potentiometer means included in the second said reference voltage source to establish the reference voltage applied to said comparator during said second setting of the relay means, whereby the mass number of the center of a scanned mass spectrum may be selected.