ACCUMULATION AND STORAGE OF IONIZED DUPLEX DNA-MOLECULES IN A QUADRUPOLE ION-TRAP

Evidence for the accumulation and storage of ionized duplex DNA molecu les in a quadrupole ion trap is presented. Aqueous solutions of comple mentary single-strand molecules of DNA were annealed to form duplexes in solution and subjected to electrospray ionization. The ions liberat ed in this process were transported through an atmosphere/vacuum inter face and injected into a quadrupole ion trap operated with a bath gas present at a pressure of 1 mTorr. Despite the roughly 2 order of magni tude poorer signal levels noted for electrospray of aqueous solutions relative to those observed for single-strand oligonucleotides in metha nol solutions, aqueous solutions were used to avoid denaturing the dup lexes. Ion trap mass spectra are reported here for duplexes consisting of two complementary 20-mer single strands and two complementary 10-m ers. Tandem mass spectrometry results are also reported for the 10-mer duplex. These results are significant in that they indicate that the ions are kinetically stable under the ion injection, storage, and mass analysis conditions of the quadrupole ion trap operated with a relati vely high pressure of bath gas. The tools of ion trap mass spectrometr y can therefore be applied to this important class of compounds.