Sequence verification of oligonucleotides by electrospray quadrupole time-of flight mass spectrometry.

The combination of electrospray ionization (ESI) and quadrupole time-of-flight (Q-Tof) mass spectrometry presents a powerful tool to verify/determine the sequence of oligonucleotides. An ESI-Q-Tof instrument provides better sensitivity and much higher resolution compared with either ESI-triple quadrupole or ESI-ion trap devices. With high-resolution capability, the quadrupole time-of-flight instrument can provide an isotope pattern to support the charge state assignment. This will improve the reliability of the assignments of sequence-related w or a-Base series ions and lead to accurate determination of the oligonucleotide sequence.