Product category:
Mass spectrometers
News Release from: ChemSW | Subject: Best practices in mass spectral library usage
Edited by the Laboratorytalk Editorial
Team on 19 January 2007
Best practices in mass spectral library
usage
ChemSW releases detailed white paper which explains best practices for accurate GC/MS structural identification and spectra interpretation of unknown compounds
ChemSW has announced the release of its latest in-depth white paper, this one detailing best practices in mass spectral library usage for accurate GC/MS structural identification and spectra interpretation of unknown compounds Companies that must analyse unknown compounds for their R+D and manufacturing processes must ensure that their final determinations are valid
This article was originally published on Laboratorytalk on 3 Sep 2001 at 8.00am (UK)
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Sometimes millions of dollars are at stake.
At a minimum, to ensure that this is accomplished, mass spectral libraries (databases) of validated chemical compounds are used to compare spectra and compound identification information against the unknowns to achieve accurate results.
Unfortunately, compound comparison is not a straightforward process analysts often overlook all the criteria they must compare in the rush to provide a quick answer.
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Best practices take the minimum comparison that all analysts must perform and leverage the use of and capabilities provided by these databases by leveraging the abilities of the analysts, processes, and technology involved to best effect.
This white paper delves into the best practices involved in using mass spectral libraries to ensure accurate analyses.
"Do you want the quick answer or the right one?," asks Brian Stafford, president of ChemSW.
"Analysts often spend extra time performing analyses of unknown compounds to ensure that their identification is correct.
"Sometimes that means telling management that more time is needed to focus on their investigation in the middle of a hectic schedule and pressing deadlines.
"Sometimes mistakes are made.
"Sometimes those mistakes don't amount to much and can be quickly corrected, but sometimes those mistakes can result in significant financial loss.
"The key to getting it right is to implement best practices so that identifying compounds accurately becomes standard operating procedure.
"Our white paper provides the details on how to do this".
Entitled 'Best practices in mass spectral library usage for accurate structural identification and spectra interpretation of unknown compounds', the white paper examines the different data management phases of a mass spectral analyses, the features and functions of mass spectral search programs and libraries, and how to utilise those resources most effectively.
Because no software can yet be relied upon to identify compounds with complete accuracy, access to comparison data is just the start when determining accurate compound analyses; the analyst's brain is still the most important tool they have.
This white paper therefore goes beyond a description of the common problems and software solutions available by providing a in-depth interview of industry expert Professor David Sparkman on how to perform accurate compound identification using industry tools.
Sparkman provides insights into how to leverage the Nist05 Database using the nist MS search program.
"In a GC/MS dataset, the first step is to look for a reconstructed total ion current [RTIC] chromatographic peak that represents an analyte," Sparkman explains.
Unfortunately, identifying the unknown is seldom a straightforward comparison to the spectra in the mass spectral database.
"Often, a spectrum of the unknown compound is not in the library.
"The best match in this case may only be a library spectrum that is similar.
"This similar spectrum may or may not be of a similar compound.
"The validity of the results is always at the discretion of the analyst.
"Chemists identify unknown compounds, not library search programs".
Best practices in mass spectral library utilisation require using the right tools correctly for the right task and knowing how to get the most out of those tools.
Thus, not only is the quality of the search results dependent on the quality of the spectra in the database, the performance of the library search program, and the spectrum of the unknown, success is also dependant upon the analyst's knowledge of how to use these to best effect.
This 25-page white paper details best practices in using the Nist MS Search program, a close look at the underlying algorithms, a number of screen shots illustrating Prof Sparkman's points, and numerous tips on how to perform accurate identifications.
The white paper is free and available on request from ChemSW.
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