Signal losses in pesticide analysis using the broadband isolation waveform in a commercial quadrupole ion trap to accomplish precursor ion isolation in tandem mass spectrometry

Signal losses due to precursor ion isolation in a quadrupole-ion-trap mass spectrometer were studied using selected pesticides as model compounds. These signal losses originate from isolations of ion populations employing the broadband isolation (bbiso) waveform used in the Varian quadrupole ion-trap precursor ion isolation protocol. Signal losses were found to be ‘precursor ion structure’ dependent upon isolation using the bbiso. The effect of the bbiso waveform on the ionic structure and nature of substituents on the precursor ion was investigated. Isolation of old electron radical molecular ions of the type [M^+?] showed remarkable signal losses compared with isolation of fragment ions derived from the same compounds. The impact of the bbiso waveform on the response of the instrument using mass spectrometry/mass spectrometry and the bbiso waveform was also examined. The response of the instrument as related to the calculated Instrument Detection Limits was observed to parallel ion population losses.