A Pascal Program for Mass Spectral Isotope Cluster Identification

Abstract

Abstract : A new isotope cluster identification program, named Reverse Cluster Search (RCS) is presented in full to assist the mass spectrometrist in the identification of unknowns. Given a clean, complete isotope cluster from a mass spectrum, its empirical formula can be found through the calculations of RCS. RCS was tested on known spectra which fit certain parameters of composition and spectral quality. Correlation between the matches given by RCS and the actual formula was excellent. RCS was written to run on both a DEC VAXStation 3500 and IBM PC compatibles. A companion program is also included which is called Forward Cluster Search (FCS). FCS will calculate theoretical mass spectral isotope clusters from empirical formula data. The purpose of this report is to provide the complete code for a Pascal program which is called Reverse Cluster Search (RCS). Our goal was to develop a computer program to rapidly identify chemical formulas from mass spectral isotope cluster data requiring minimal disk storage and memory. Relying entirely upon low resolution mass spectral cluster data to predict or confirm empirical formulas is not recommended. High resolution, exact mass data is always preferred when complete confidence is required in the formula assignment; however, the presence of certain isotropic elements must be supported by the cluster data.