Ionization detector for the gas chromatography and analytical methods for this purpose.

摘要

The anode and cathode of an ionization detector are constituted respectively by a stainless steel tube 32 and a copper foil electrode 30 which lines a passage 12 in a housing 10 of inert material and is in electrical contact with a fitting 26 which is connected to the end of a chromatographic column 24 and is fitted at its inner end with a frit disc 28. The space between the electrodes forms a detection chamber which, in operation, is filled with a cloud of electrons produced by bombarding a photoemissive foil 38 with ultra-violet radiation from a lamp 44 inserted in a well 20 in the housing 10. The photoemissive foil 38 is secured to a holder 36 carried by a threaded plug 34 screwed into a tapped opening 22 in the housing 10. The foil is connected to the cathode by way of a connector 40 and conductor 42. In operation, the atoms of a carrier gas such as argon which is used to elute samples from the chromatographic column 24 are raised to their metastable state by electron collisions and then ionize the sample molecules. This causes a current flow between the electrodes as a result of potential applied by a power supply 46, this current flow being amplified by an amplifier 48 and recorded by a recorder 50.