Headspace sampling for gas chromatographic analysis, which in its truest
sense implies the direct injection of the mixture of vapors in equilibrium with
a sample held within a confined space, possesses a desirable and appealing
simplicity. It also offers a distinct advantage in that sample work-up
procedures have been avoided. These latter usually involve distillation,
extraction, and/or adsorption processes, and almost invariably engender
quantitative and, frequently lead to, qualitative changes in the composition
of the sample, which are certainly good reasons to favor simple headspace
injections.