Diquat  Terpyridine isomers
Content Handbook M
Outline of method
Terpyridine isomers are extracted from the sample with ethyl acetate. The impurities are selectively removed from the ethyl acetate extractant using a solid phase extraction (SPE) procedure prior to determination by liquid chromatography coupled to a tandem quadrupole mass spectrometer. Multiple reaction monitoring (MRM) of four different ion transitions is performed. Using the response from one ion transition channel, the amount of terpyridine is quantified using single point calibration. Confirmation of identity of terpyridine isomers is obtained via peak area ratio matching of the four monitored ion transition channels.
The method is usable for TC and SL-formulations.