By using different analytical column stationary phases, a large variety of compounds can be analyzed. The FID is responds with nearly uniform response to most organic compounds and is quite linear over several orders of magnitude (has a large useful dynamic range). The FID is not damaged by overloading, and maintenance is generally limited to periodic changing of the flame jet(s). The FID requires hydrogen gas to operate, so suitable safety measures should be followed for the storage and use of compressed hydrogen gas. Further, the FID destroys the sample.
Another general purpose detector is the Thermal Conductivity Detector, or TCD. A TCD is actually a bit more fragile than an FID, typically has a lower sensitivity and often has a baseline that wanders more than the FID. However, the TCD can be used for some materials that give no FID response: the rare gases. In addition, a TCD is non-destructive; this makes the TCD suitable to preparative analysis in which the GC is used to purify components. Another interesting feature of the TCD is that it can be configured with two columns; though only one column is used at a time (the other provides the carrier gas reference); switching between analytical columns involves little more than flipping a switch.
Other general purpose and medium selectivity detectors include the Electron Capture Detector (ECD), the Nitrogen Phosphorus Detector (NPD), Photoionization Detector (PID), Flame Photometric Detector (FPD) and others. The ECD is used when picogram sensitivities are needed for compounds with very large electron capture cross sections, such as halogenated pesticides (endrin, DDT, etc). The ECD shows little to no response for other compounds. The NPD is, of course, sensitive to compounds containing nitrogen or phosphorus atoms. The PID and FPD would be considered class-specific detectors, offering high sensitivity to compounds with radiation absorption characteristics appropriate for the photon source used.
High selectivity can be gained by coupling a GC to either a mass spectrometer or an infrared spectrometer.