Detection of Oligonucleotides by External Injection into an Ion Trap Storage/Reflectron Time-of-flight Device

✍ Scribed by Ling He; Yan-Hui Liu; Yongdong Zhu; David M. Lubman

• Book ID: 101238507
• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 218 KB
• Volume: 11
• Category: Article
• ISSN: 0951-4198
• DOI: 10.1002/(sici)1097-0231(19970830)11:13<1440::aid-rcm25>3.0.co;2-9

✦ Synopsis

The detection of oligonucleotides has been studied using external injection of Matrix-assisted laser desorption/ionization (MALDI) produced ions into a quadrupole ion trap storage device. The ions stored in the trap are then detected by pulsed DC ejection into a reflectron time-of-flight mass spectrometer. It is shown that by using a low acceleration voltage from the probe tip and external injection into the trap that 3-mers to 9-mers can be stored for 20-50 ms and detected as intact ions. In comparison, direct MALDI inside the trap resulted in extensive fragmentation as a function of storage time. Using the external injection method with a He buffer gas in the trap yields a resolution of 250-400 in the ion trap storage/reflectron time-of-flight mass spectrometer.

The resolution can be further enhanced to 400-800 using a bipolar extraction method. In addition, the trapping efficiency for the injection of externally produced ions into the trap can be enhanced using a dynamic trapping method. The MALDI mass spectra produced by this methodology result in excellent signal-to-noise ratio due to the capabilities of the trap for eliminating low mass matrix background from the spectra.