Charge reduction in electrospray mass spectrometry

摘要

The charge state of ions produced by electrospray ionization is reduced in a controlled manner to yield predominantly singly charged ions through reactions with bipolar ions generated using a <210>Po alpha particle source or equivalent. The multiply charged ions generated by the electrospray undergo charge reduction in a charge reduction chamber. The charge-reduced ions are then detected using a commercial orthogonal electrospray TOF mass spectrometer, although the charge reduction chamber can be adapted to virtually any mass analyzer. The results obtained exhibit a signal intensity drop-off with increased oligonucleotide size similar to that observed with MALDI mass spectrometry, yet with the softness of ESI and without the off-line sample purification and pre-separation required by MALDI.