Biomolecular dual-ion-trap mass analyzer.

We developed the first dual-ion-trap mass analyzer which can detect ions with a high mass-to-charge ratio (m/z > 6000). The first ion trap is a quadrupole ion trap (QIT), which was operated by step scanning of the trapping frequency for a sample containing mixtures of biomolecules. The second ion trap, linear ion trap (LIT), was utilized to capture selected ions ejected out of the QIT so that all ions from the QIT can be examined one by one. It was found that the ions can be transferred from the QIT to the LIT with ~60% efficiency for large biomolecular ions with high m/z. This is by far the highest transfer efficiency in the dual ion trap device for high-mass ions.