Although a number of methods based on spectrophotometry, gas chromatography (GC) and ion chromatography (IC) have been used for the analysis of inorganic toxic anions, gas chromatography/mass spectrometry (GC/MS) after derivatization is considered to be most reliable to determine such anions in biological samples due to its high selectivity.
  We here review the analytical methods to prove inorganic toxic anion poisoning using GC/MS. The causative substances of poisoning include hydrogen sulfide, polysulfides, cyanide, azide, nitrogen oxide, formalin, methanol, ethanol, methyl bromide and hydrofluoric acid.
  The key points for efficient derivatization of each anion and possibility of establishing simultaneous screening method for these anionic compounds are also discussed.