ACD Labs Logo

Accelerated Deformulation of LC/MS and GC/MS Data Through Database Searching

Published online at Chromatography Today.

Authors: Matthew J Binnington, Anne Marie Smith, Richard Lee


As the technical capabilities of mass spectrometers advance - for example, greater mass accuracy and resolution - the demand for efficient analysis of increasingly complex mass spectrometry (MS) samples has grown accordingly. Liquid and gas chromatography (LC, GC) represent effective tools for reducing sample complexity, however co-elution of experimental components remains nearly unavoidable.

Though such mass spectrometer enhancements have led to greater accuracy in determining the elemental composition of sample components, their outputs lack structural information. Chemical structure data is necessary to identify sample constituents, and critical to the process of distinguishing 'known unknowns'—components that have been previously identified—from true unknowns in MS analyses. This process, termed deformulation, typically represents a major analytical bottleneck. This is due to the significant time required to confirm the presence of all known unknowns, before moving on to isolation of any true unknowns for further characterisation.

This technical article presents a two-step deformulation approach designed to efficiently identify known unknowns by 1) utilising LC/MS/MS data to perform mass spectral searching of available libraries, and then 2) performing follow-up screening of any poorly resolved components against structural databases using predicted chemical formula and accurate mass information. This workflow utilises ACD/MS Workbook Suite, paired with the ACD/MS Structure ID add-on, to expedite deformulation and ensure that full elucidation activities are limited to only those components that have not been previously identified.

Read the complete article online here.

Chromatography Today, November 2018, Volume 11 Issue 4, Buyers' Guide 2019