A DETECTOR BY-PASS VALVE

Gas chromatographic detection systems are subject to two main sources of interference: solvent elution and liquid phase bleed. Solvent elution, especially with large injection volumes, often produces undesirable tailing, over-loading or fouling of detector, and flame extinguishment. Column liquid phase bleed causes detector and combustion tube contamination which may result in lost sensitivity, anomalous behavior and catalyst poisoning. Most systems have attempted to circumvent these undesirable features by venting the solvent and discontinuing carrier flow when the detector is not in actual use. Solvent venting, while desirable, is not, as presently implemented, an entirely satisfactory answer, since discontinuing the carrier flow causes disruption of detector equilibrium or, in the case of flame detectors, discontinues ignition. In both instances, a re-equilibration period is required before detection equilibrium and response is restored. © 1968, Oxford University Press. All rights reserved.