The use of low-energy (7 eV Elab) reactive collisions with ammonia provides a highly specific method for the characterization of trichothecenes since the collisions between the protonated molecule and ammonia not only produce ions formed by collisionally activated dissociation but ammonium adduct ions and ions formed by substitution reactions. The good detection limits (20-300 pg) and good quantitative reproducibility (relative standard deviations are 5-10%) mean that the use of reactive collisions with ammonia is also very suitable for monitoring and quantitative analyses.