Aim: It is challenging to develop a multiple reaction monitoring (MRM) method for some disulfide-bonded peptides with inefficient collision-induced dissociation fragmentation. This study describes a new methodology using differential mobility spectrometry (DMS) combined with multiple ion monitoring (MIM) to enhance bioanalytical sensitivity for sunflower trypsin inhibitor. Results: By combining DMS with MIM to monitor the intact precursor ion in Q1 and Q3 MS analyzers, a lower limit of quantitation at 0.125 ng/ml was achieved to quantify sunflower trypsin inhibitor in rat plasma, representing a 40-fold sensitivity improvement over MIM without DMS. Conclusion: DMS coupled with MIM method provides triple quadrupole MS users an effective means to overcome challenges in analyzing disulfide-bonded peptides or other analytes that do not have useful collision-induced dissociation fragment ions for MRM analysis.
Keywords:
- differential mobility spectrometry
- disulfide-bonded peptides
- multiple ion monitoring