Ion gate sample gas inlet control for gas chromatograph analyzer

Abstract

A gas tight cell receives an unmetered stream of sample gas. The cell is divided into a reaction chamber, as drift chamber and an ion collector chamber by transverse shutter grids normally carrying an ion repellent charge. The inlet of a chromatograph analytical column is connected to the outlet of the cell ion collector chamber. Inert gas admitted to the ion collector chamber is divided into a drift gas stream and into an oppositely directed carrier gas stream. The drift gas flows from the collector chamber through the drift chamber and out the reaction chamber. The carrier gas flows from the collector chamber through a deionizer into the chromatograph column. An electrostatic field urges sample gas ions from the reaction chamber toward the ion collection chamber. The ions are blocked from entering or exiting from the intervening drift chamber by the charge on the shutter grids. At selected times the repellent charges are removed from the shutter grids to allow a group of sample gas ions to traverse the drift chamber and enter the ion collection chamber. Such ions become entrained in the carrier gas stream and are transported thereby through the deionizer into the chromatograph column. The waveform of the current induced in the deionizer by sample gas ions passing therethrough provides information on the time, volume and shape of the gas sample admitted to the chromatograph column.