The GC/PID is a form of organic chemical analysis in which a gas chromatograph is equipped with a photionization detector. The PID is a highly sensitive and uniquely selective detector. Using UV lamps with different energies, it selectively detects aromatics, polyaromatic hydrocarbons, phenols, aliphatic hydrocarbons, unsaturated halocarbons like ketones and aldehydes, and sulfur gases. As a non-destructive detector, the PID can be connected in series with an ELCD or any other detector in order to provide for more complete coverage of both halogenated and non halogenated compounds in the same chromatographic analysis.