Discharge ionization detector

Claim 1

A discharge ionization detector, comprising: a detector body of an electrically-conductive material defining first and second chamber wells coaxially disposed and having a common internal wall with an aperture therein; said body including an inlet to the first chamber well for admitting an emission gas, and an inlet to the second chamber well for admitting the column effluent of a chromatograph; said body having a single vent opening from the second chamber well in substantial coaxial alignment with the column effluent inlet; a first demountable electrode assembly including a flange and gasket seal to be mounted to the detector body to close the first chamber well, and having a pair of electrodes for generating an exposed glow discharge emission directed through the aperture into the second chamber well to cause ionization of species in the column effluent; a second demountable electrode assembly including a flange and gasket seal to be mounted to the detector body to close the second chamber well, and having a collector electrode, to be coupled to an electrometer providing an indication of ionized species in the column effluent, and a polarizing electrode, to be negatively charged, for generating an electric field with respect to the collector electrode to cause electrons produced by species ionization to be accelerated toward the collector electrode; the column effluent inlet to the second chamber well directing the flow of column effluent transversely to the discharge emission directed through the aperture; the polarizing electrode disposed within the second chamber to be substantially aligned with the column effluent inlet and being of an annular configuration oriented in a plane transverse to the discharge emission; the collector electrode disposed in substantially coaxial alignment with the aperture; and means for coupling said detector body to ground potential, to reduce the entry of glow discharge-produced electrons into the second chamber well.