Gas chromatography/mass spectrometry (GC/MS) is a method that combines the features of a gas chromatograph and a mass spectrometer. Whereas the gas chromatograph can separate volatile and semivolatile compounds with great resolution, the mass spectrometer can provide detailed structural information on them. So, many scientists consider GC/MS analysis as a tool for conclusive proof of identity. Typical uses are drug testing, environmental testing, and manufacturing quality control.