DETERMINATION OF PYRETHROID INSECTICIDES BY ION-TRAP GC-MS-MS

Selected ejection isobutane chemical ionization (SECI) of pyrethroid i nsecticides was compared to collisionally activated dissociation (CAD) of selected ions by using a benchtop quadrupole ion trap mass spectro meter. SECI-CAD was successfully demonstrated for compounds of differe nt masses which elute closely. SECI produced a characteristic cleavage at the ester bond for most compounds, while SECI-CAD of the protonate d species showed this cleavage as well, but with a reduced number of d ifferent fragment ions for the higher mass pyrethroids. The limit of d etection showed a loss of one order of magnitude during the isolation step of the ions followed by a loss of half or none of the ion intensi ty during the activation step. Typical detection limits were in the pp b range.