PHOTOIONIZATION DETECTOR FOR GAS CHROMATOGRAPHY Russian patent published in 1995 - IPC

FIELD: chromatographic instrument engineering. SUBSTANCE: photoionization detector has UV radiation source 1, which has to be a gas-discharge lamp with window made of material, which is transparent for UV radiation. Detector also has ionization chamber, which has case, entrance window for UV radiation, inlet and outlet channel 6 and 8. Tubular polarizing electrode 7 and annular collecting electrode 3 are mounted inside the chamber coaxially. Diameter of electrode 3 is larger than diameter of entrance window of ionization chamber. Screen 4, made in form of body of rotation, is mounted onto polarizing electrode at lamp side. Screen 4 is made of electro-insulating material, which is non-transparent for UV radiation. Screen 4 has channels for output of gas under test into ionization zone. Total cross-section of the channels is no less than cross-section of internal channel of tubular electrode. Diameter of the screen is larger than diameter of entrance window of UV radiation chamber, but is lesser than internal diameter of ionization chamber. EFFECT: improved quality of operation. 1 dwg