Gas Chromatography/Mass Spectrometry (GC/MS) is a combination of two instrumental techniques, gas chromatography and mass spectrometry. The gas chromatograph is used to separate a mixture into component parts and deliver them to the mass spectrometer. The mass spectrometer breaks the molecules into ions and records the resulting spectrum. This spectrum conclusively identifies the compound.
Fourier Transform-Infrared Spectroscopy (FT-IR) is an instrumental technique used to identify compounds based on their infrared absorption characteristics. The spectra produced from this technique are used to conclusively identify compounds.