This is a research project supported by the R&D of Applied Biosystems / Sciex (Concord, Canada; Dr. Tom Covey) and University of Groningen (Dr. Andries Bruins, Netherlands), whihc aims at developing novel LC-MS/MS instrumentaiton and experimental approaches to reduce chemical bakcground noise for sensitive trace analysis.
The interference of chemical background ions (chemical noise) has been a problem since the inception of mass spectrometry. With the advancement of ionization and transmission efficiency in LC-MS, reduction of chemical backgrounds becomes an acute challenge for trace analysis. In this project using a custom-designed collision cell by Sciex (a LC-MS manufacturer), a novel method of reducing chemcial background noise has been developed (Guo et al. World Patent WO 2007/092873; Anal. Chem. 2007, 79, 4013-4021). This is based on exclusive reactions of chosen neutral reagents with background ions (not with analytes!). When this is combined with the mass filtering function of a quadrupole mass spectrometer, chemical noise are selectively removed and, as a result, a significant improvement of signal-to-noise ratio up to 5-20 times has been achieved. The technique has also been implemented and tested on a commercial quadrupole LC-MS system. Although still preliminary, this approach has shown great promise of developing novel MS instrumetnation by manufacturers and fundamental researches.