Considerations in Developing a GCMS Accurate Mass Screening Workflow for Environmental PollutantsEmerging Environmental Applications for High Resolution Mass Spectrometry
Poster Presentation
Presented by T. Anumol
Prepared by B. White1, R. Davis2, S. Nieto3
1 - Agilent Technologies, Spectrum Building, Becquerel Ave, Didcot, Oxfordshire, OX11 0RA, United Kingdom
2 - Agilent Technologies, Lakeside 5500, Cheadle Royal Bus Park, Cheadle, Cheadle, SK8 3GR, United Kingdom
3 - Agilent Technologies, 5301 Stevens Creek Blvd, Santa Clara, CA, 95051, United States
Contact Information: [email protected]; 302-636-3969
ABSTRACT
The Evolution of screening workflows has been to make them more intelligent requiring less human interaction in the evaluation of the data. In order to be able to minimize the human evaluation it is key to include all aspects of the data such as Accurate Mass of the Quan Ion as well as Qualifiers, Retention time of analyte, use of the Library Match score as a key to minimize false positives, and no of qualifying ions. The goal here is that a component that satisfies all four of the above criteria can be deemed as statistically being present with no human evaluation being required. In this poster presentation, we will discuss untargeted screening and the benefits of traditional EI spectra to enable this.
The key to the targeted screening workflow in this work was a true accurate mass library, which is curated with empirical m/z have been converted to the theoretical based on accurate mass as well as isotope ratios using Fragment Formula Annotation tool. The database included full EI spectra, retention times, molecular formula, and CAS number for its over with over 1000 entries. The GC/HR MS solution utilized mid column backflush to ensure consistent retention times and instrument robustness. The employed retention time locking technology allows user to ensure that all components elute at the specified time.
In addition to the targeted screening workflow, untargeted screening of deconvoluted spectra against the NIST spectral library was performed. The software tool verifies if the accurate mass ions of the fragments fit with the assignment giving far more confidence in the spectral hit.
The combination of these tools results in a comprehensive approach to a thorough targeted screening workflow for environmental pollutants in addition to untargeted accurate mass screening vs a nominal mass library.
