ABSTRACT
This chapter deals with the elution method of chromatography using a gaseous mobile phase and a liquid or solid stationary phase. The basic instrumentation necessary to accomplish the chromatography is extremely simple. The analyzer section contains all of the basic elements of the chromatograph, namely, columns, sample valves, column switching valves, and detectors, all enclosed in a precisely thermostatted oven. Very small sample and detector volumes are required as well as critical attention to plumbing details to avoid unswept volumes that degrade the chromatographic peaks by creating long tails on the trailing edges. One of the most severe limitations of chromatography for process control is that of "analysis cycle time". The peak processor section of the programmable-controller has as its primary functions the detection of chromatographic peaks produced by the sample constituents of interest and the determination of the appropriate peak areas or peak heights.
