Possible False Positive Identifications in Gas Chromatography/Mass Spectrometry (GC/MS) Analysis in Chemical Weapons Convention (CWC) Inspections. Part I Comparison to NIST Library Spectra

Published

October 16, 2008

Author(s)

William G. Mallard

Abstract

The possibility of making false positive identifications during on-site analysis because of similarity between the mass spectra of scheduled and unscheduled chemicals has been of concern for some time. However, until an official Organization for the Prohibition of Chemical Weapons (OPCW) analytical database, the instrument and the analysis software were in place, it was not possible to evaluate the risk of false positives. A preliminary evaluation of the mass spectral database accepted by the OPCW has been performed. False positive identification involving Schedule 1 chemicals are the most numerous and the most serious in terms of CWC violations. Most of the Schedule 1 false positives arise from spectra of phosphonofluoridates (Schedule 1.A.01). The use of measured retention indices (already approved by the OPCW) or even estimated retention indices will eliminate all of the Schedule 1.A.01 false positive identifications found in this work. The dialkylaminoethyl alkylphosphonothiolates (Schedule 1.A.03) are the second most common class for which the spectra are likely to give false positives. The chance of false positives within this class is lower, but there is not enough retention data to insure the elimination of the Schedule 1.A.03 false positives.

Citation

Possible False Positive Identifications in Gas Chromatography/Mass Spectrometry (GC/MS) Analysis in Chemical Weapons Convention (CWC) Inspections. Part I Comparison to NIST Library Spectra

Pub Type

Others

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Keywords

chemical weapons, mass spectra, retention index

Citation

Mallard, W. (2008), Possible False Positive Identifications in Gas Chromatography/Mass Spectrometry (GC/MS) Analysis in Chemical Weapons Convention (CWC) Inspections. Part I Comparison to NIST Library Spectra, Possible False Positive Identifications in Gas Chromatography/Mass Spectrometry (GC/MS) Analysis in Chemical Weapons Convention (CWC) Inspections. Part I Comparison to NIST Library Spectra, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=831501 (Accessed April 23, 2024)