Combining electrospray ionization and the flowing afterglow method.

The design and implementation of a simple electrospray ionization source for a flowing afterglow/triple quadrupole device are described. Ions can be electrosprayed directly into the room temperature flow tube through a heated capillary without the need for differential pumping or ion focusing. Detected ion currents at the detector sampling orifice as high as 3 pA have been achieved, and the mass spectra indicate little or no re-clustering of the desolvated ions with the background solvent vapor in the flow tube. Spatially and temporally resolved ion/molecule reactions of electrosprayed ions can be carried out in the flow reactor under thermal energy conditions. Sufficient ion densities can be achieved for tandem mass spectrometric experiments in the triple quadrupole analyzer, including energy-resolved collision-induced dissociation. Selected chemical applications illustrating these features are described, including proton transfer reactions with aromatic polysulfonate dianions and multiply protonated polypeptides and threshold CID of a doubly charged transition metal coordination complex.