| 摘要 |
A preconcentrator for analyzing trace constituents in gases wherein a sample gas is introduced to a confined sorbent which thereafter is evacuated by a vacuum pump and a low-pressure carrier gas passes through the sorbent while it is desorbing, wherein the desorbed trace constituents are carried by the carrier gas to a detector that operates at low pressure such as a mass spectrometer. Because the mass of the carrier gas which carries the desorbed trace consituents to the detector is at a lower pressure and therefore has less density than the sample gas, the relative mass of trace constituents in the carrier gas is much greater than in the sample gas. The sample gas can be hot to assist desorption or a gas which reacts with trace constituents of interest to improve their detection. Valves located in the system between the sample gas intake, the carrier gas supply, the vacuum pump for the system and the detector operate to admit the sample gas, isolate the system, create a vacuum in the system, establish the sample gas flow, and to carry the trace consituents to the detector. Preconcentrators can be placed in parallel, whereby when one is desorbing and analyzing trace elements, the other is receiving the sample gas.
|
