These compounds are frequently trapped in the soil-gas spaces and are difficult to analyze because of the physical problems of obtaining and preserving the sample as well as the challenges inherent in the subsequent analysis. Here's how it works. The ions enter a drift region where they move through an applied field toward a collector electrode. The electrode current is monitored continuously, allowing a mobility spectrum to be measured. The specificity is imparted by the ionization preferences of analytes and the mobility differences of the ion clusters.
Separations are a function of ion size.
Analytes with higher proton or electron affinities than other constituents of the ambient environment are differentiated and detected easily. Analytes with low affinities can be measured when competing chemicals with higher affinities are not present.