Utility of peak shape analyses in determining unresolved interferences in exact mass measurements at low resolution

Low resolution methods can provide exact mass data comparable to that obtained with high resolution instrumentation and offer potential advantages in throughput and robustness. However, low resolution exact mass techniques have realized limit-ed use largely because of the possibility of errors caused by unresolved interferences. Here the utility of statistical peak shape analysis for determining unresolved interferences at low resolution is considered. Equations describing the effect of unresolved interferences on statistical peak shape parameters are developed and used to investigate the extent to which evaluations of peak shape can be used to reduce the likelihood of mass measurement errors. Peak shape analysis is shown to be a highly effective and sensitive method of determining unresolved interferences. Mass measurement errors resulting from undetermined interferences a-e found to increase with increasing relative abundance of the interfering peak, to increase with decreasing resolution, and to increase with decreasing precision in the intensity measurement. At low resolution, undetermined interferences as small as a few percent relative abundance can produce mass measurement errors in excess of 5 ppm. Peak shape analyses alone do not appear adequate to eliminate the risk of significant mass measurement errors resulting from unresolved interferences at low resolution. (C) 1998 American Society for Mass Spectrometry.