Fragmentation of toxicologically relevant drugs in negative-ion liquid chromatography-tandem mass spectrometry.

Negative-ion LC-MS analysis of drugs is applied far less frequently than positive-ion LC-MS. Data on the interpretation of negative-ion MS-MS spectra are even more scarce. Therefore, following the recent review on the class-specific fragmentation of toxicologically relevant compounds in positive-ion MS-MS, it was decided to perform a similar study in negative-ion MS-MS. To this end, a set of over 500 negative-ion MS-MS spectra was collected from three libraries applied in toxicological general unknown screening and systematic toxicological analysis. The compounds involved were classified by chemical and therapeutic class. The MS-MS spectra were manually interpreted and relevant interpretation data were searched for in the scientific literature. The emphasis in the discussion is on class-specific fragmentation, because discussing fragmentation of all individual compounds would take far too much space. Negative-ion MS-MS fragmentation is discussed for a wide variety of toxicologically relevant compounds, including dihydropyridine calcium channel blockers, diuretics, barbiturates, anti-inflammatory drugs, anti-diabetics, sulfonamide and betalactam antibiotics, and a number of classes of pesticides.