DNA sequencing with blackbody infrared radiative dissociation of electrosprayed ions

As shown by Williams for positive multiply-charged ions, negative electrosprayed ions trapped in a Fourier-transform ion cyclotron resonance mass spectrometer can be dissociated efficiently with BIRD. For a 50-mer DNA, an ion cell wall temperature of 90°C gives no dissociation and 120°C gives only uninformative base loss. However, 150°C gives extensive dissociation producing ionic products qualitatively similar to those from laser IR, collisionally activated, and nozzle-skimmer dissociation. Under the conditions used, BIRD produces more fragment ions that have lost an additional base (AH). Structurally informative BIRD spectra are also observed for a 100-mer DNA and a double-strand 64-mer DNA. For both samples, BIRD successfully ‘boiled off’ non-covalent adducts that produced an uninterpretable spectrum, while laser IR was only successful in this for the ds 64-mer.