2.4 Advanced GC Systems
Most commercial GC systems come with ports for at least two injectors, and therefore two columns and two detectors. This allows for versatility and some inventive operational designs. With a special ferrule, two columns with different stationary phases can be inserted into one injection port allowing two analyses per injection and confirmatory analysis.
Confirmatory analysis, with respect to chromatography, is usually restricted to mass spectrometry detection, but when a sample is analyzed on two columns with different stationary phases, the likelihood of two different compounds yielding the same retention time on both columns and the same response on identical detectors is highly unlikely. Thus, dual column analysis usually produces confirmatory identification.
More enhanced arrangements include detectors aligned in series where the effluent of one detector is passed into another detector. This arrangement does not necessarily provide confirmatory analysis, but does allow considerably more information to be collected about the analyte. Note that the first detector cannot be a destructive detector since the chemical integrity of the analyte must be intact for the operation of the second detector.
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