Knowing the unknown - State of the art of LCMS in toxicology

Liquid chromatography coupled to mass spectrometry (LC-MS) is nowadays an indispensable tool in the clinical toxicology laboratory. It allows the identification of a very high number of compounds for confirmation of positive immunoassay results as well as the detection of yet unknown compounds present in an intoxicated patient. In clinical toxicological laboratories ion traps and triple stage quadrupole instruments are widely used, whereas high-resolution instruments are only used in specialized laboratories. As every analytical method also LC-MS has its limitations; the most important drawbacks are matrix effects which can lead to ionization enhancement or suppression. For the identification of a compound, 3 to 4 identification points are necessary, regardless if a high-resolution instrument is used or not.