Confirming Peak Identification in Bioanalytical Studies Utilising Xevo TQ MS Product Ion Confirmation

INTRODUCTION
The accurate quantification of candidate pharmaceuticals in bioanalysis relies on the use of sensitive, specific methodology. The advent of atmospheric pressure ionisation sources, in the late 1980s, allowed the simple interfacing of liquid chromatography with tandem quadrupole mass spectrometry. The selectivity and sensitivity provided by LC/MS/MS has made it the technique of choice for bioanalytical studies.

Bioanalytical scientists have relied on the specificity and sensitivity of the multiple reaction monitoring (MRM) MS acquisition mode to ensure that the correct analyte is quantified. However, even with the specificity of MRM analysis and modern sample preparation techniques, such as solid phase extraction, extraneous peaks can interfere during sample analysis. The appearance of an extra peak during MRM analysis could be due to chromatographic peak splitting, associated drug metabolites, or matrix interferences.

The occurrence of extra peaks during analysis would require additional experiments to correctly identify the analyte of interest. With a conventional tandem quadrupole mass spectrometer, this would require separate analysis to acquire full scan MS or full scan MS/MS spectra to confirm the identity of the peaks in question. With the introduction of the Waters® Xevo™ TQ MS, both MRM and full scan MS or product scanMS/MS can now be acquired during a single injection.