Photo ionization detector

Abstract

The invention discloses a photo ionization detector, comprising a vacuum ultraviolet lamp and an ionization chamber, wherein the ionization chamber comprises two electrodes with minor arc radial cross sections, wherein the electrodes are arranged symmetrically, and comprise a polarized electrode and a collecting electrode. The two electrodes insert into the interior of polytetrafluoroethylene tank in the ionization chamber, such that base current and noise of the electrodes caused by irradiation of the vacuum ultraviolet lamp are avoided. The detector contains an automatically cleaning system to prevent decreasing of sensitivity of the detector caused by pollution of light window and electrodes when the detector is in a continuous operation for a long time. The photo ionization detector suits as a detector of a portable gas chromatograph and a rapid gas chromatograph.

Description

technical field

[0001] The invention relates to a gas chromatography analysis instrument, in particular to a photoionization detector. Background technique

[0002] The photoionization detector (PID) uses vacuum ultraviolet radiation to ionize the measured components to generate signals, which can be used alone as a chromatographic detector or used in series with flame ionization detectors, mass spectrometers and other detectors.

[0003] The working principle of the photoionization detector is: the effluent of the chromatographic column is brought into the ionization chamber by the carrier gas, the gas to be measured is ionized under the irradiation of vacuum ultraviolet light, and the generated electrons and positive ions are respectively charged to the ionization chamber under the electric field of the polarized plate. The migration of the two poles causes changes in the induced charge of the collecting electrode plate, and the weak current passes through the amplifier to...

Images