Strategy to improve the quantitative LC-MS analysis of molecular ions resistant to gas-phase collision induced dissociation: application to disulfide-rich cyclic peptides

Anal Chem. 2014 Dec 2;86(23):11523-7. doi: 10.1021/ac502678y. Epub 2014 Nov 18.

Abstract

Due to observed collision induced dissociation (CID) fragmentation inefficiency, developing sensitive liquid chromatography tandem mass spectrometry (LC-MS/MS) assays for CID resistant compounds is especially challenging. As an alternative to traditional LC-MS/MS, we present here a methodology that preserves the intact analyte ion for quantification by selectively filtering ions while reducing chemical noise. Utilizing a quadrupole-Orbitrap MS, the target ion is selectively isolated while interfering matrix components undergo MS/MS fragmentation by CID, allowing noise-free detection of the analyte's surviving molecular ion. In this manner, CID affords additional selectivity during high resolution accurate mass analysis by elimination of isobaric interferences, a fundamentally different concept than the traditional approach of monitoring a target analyte's unique fragment following CID. This survivor-selected ion monitoring (survivor-SIM) approach has allowed sensitive and specific detection of disulfide-rich cyclic peptides extracted from plasma.

MeSH terms

  • Chromatography, Liquid
  • Disulfides / chemistry*
  • Humans
  • Ions / analysis
  • Ions / chemistry
  • Peptides, Cyclic / blood*
  • Peptides, Cyclic / chemistry*
  • Tandem Mass Spectrometry

Substances

  • Disulfides
  • Ions
  • Peptides, Cyclic