Improved resolution in the detection of oligonucleotides up to 60-mers in matrix-assisted laser desorption/ionization time-of-flight mass spectrometry using pulsed–delayed extraction with a simple high voltage transistor switch SPONSOR REFEREE: W.H. Benner, Engineering Division, Berkeley National Laboratory, Building 70A, Room 2255E, 1 Cyclotron Road, Berkeley, CA 94720, USA

Abstract

Pulsed–delayed extraction using a simple high voltage transistor switch together with various sample purification approaches were used to enhance the resolution in matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) of oligonucleotides up to 60 bases long. This switch can provide a 0–3 kV voltage pulse with a 75 ns fall time. A resolution of 500–900 was typically observed for samples from 5-mers to 60-mers using pulsed–delayed extraction (PDE) with the switch described herein. The resolution deteriorated to <100 for oligonucleotides of ≥65-mers. With the TOF acceleration region configuration used in this work, the resolution was found not to vary significantly over a delay range of 2–5 μs. As the DNA size increased to over 35-mer, HPLC purification was required to retain the enhancement in resolution provided by PDE MALDI-MS. © 1997 John Wiley &Sons, Ltd.