Forensic chemistry is that the application of chemistry and its subfield, forensic toxicology, during a legal setting. A forensic chemist can assist within the identification of unknown materials found at a criminal offense scene. Specialists during this field have a good array of methods and instruments to assist identify unknown substances. These include high-performance liquid chromatography, gas chromatography-mass spectrometry, atomic absorption spectroscopy, Fourier transform infrared spectroscopy, and thin layer chromatography.