ABSTRACT
There are two types of gas sample: samples that comprise a limited number of major gas components and samples that contain trace components of gases or vapors of relatively low boiling materials. The two types of sample are usually collected in quite different ways. Gas samples are usually collected in glass vessels with taps at either end, but stainless steel and Teflon vessels have also been used. Although solid particles in the sample are unlikely to affect the accuracy or precision of the analysis when determining major components, they can contaminate the chromatograph. Care should be taken to ensure that any drying agent that is used will not disproportionately adsorb any one or group of components of the mixture, otherwise the analytical results will be in error. The technique of displacing the sample into the sample valve with mercury is sometimes employed, which, although a little less convenient, allows the sample loop to be well purged with sample before analysis.
