text: The PFT can be released in a variety of ways, depending on the application, and may be as simple as spraying into the air. Samples are then collected at set times and locations, and either taken to a laboratory for analysis, or analysed in the field.
  Analysis of the samples typically involves three parts; preparation, chromatography and detection. Preparation involves removal of other impuries, for example, mixing with hydrogen then passing over a catalyst to convert oxygen to water, which is then removed with silica gel. The sample is then admitted to a gas chromatograph. This splits up the different PFTs, so a concentration value can be determined for each one.
  There are two ways PFTs are then detected; using an electron capture detector or negative ion mass spectrometry. Both techniques involve bombarding the sample with electrons, and measuring the negative ions produced. Perfluorocarbons have a particularly high affinity for electrons, so are detected in low concentrations.
  An alternative set up; the chromatograph can be omitted, and the different PFTs determined from their different masses in the mass spectrum.
  PFTs can be detected in concentrations as low a 1 part in 10 by volume (1 femtolitre in a litre).