COLLISION-INDUCED SIGNAL ENHANCEMENT - A METHOD TO INCREASE PRODUCT ION INTENSITIES IN MS MS AND MSN EXPERIMENTS/

Collision-induced signal enhancement (CISE), a new technique to enhanc e the MSn capabilities of the quadrupole ion trap, is demonstrated, CI SE is based on the chemistry, i.e., the dissociation pathways, of the analyte examined. Polysaccharides up to hexamers are used to demonstra te the capabilities of CISE to enhance signal in two distinct function al modes. Mode 1 CISE is designed to enhance the signal of an ion desi red for MSn analysis. Mode 2 CISE is designed to enhance structurally significant product ions in an MS/MS spectrum. Two different approache s can be utilized to effect the two functional modes of CISE, Both app roaches use conventional resonant excitation techniques to effect diss ociation, which is performed nonanalytically, i.e., without isolation of the ions to be dissociated. The two approaches are (1) single frequ ency resonance excitation, and (2) broad-band wave form resonant excit ation. Experimental results for Mode 1 CISE analysis demonstrate up to a 17.3-fold signal increase for the single frequency approach and 5.3 -fold using broad-band excitation. Mode 2 CISE analysis shows up to a 16.3-fold increase in signal strength with single-frequency excitation and 3.3-fold using broad-band excitation.