Combining Fragment-Ion and Neutral-Loss Matching during Mass Spectral Library Searching: A New General Purpose Algorithm Applicable to Illicit Drug Identification

A mass spectral library search algorithm that identifies compounds that differ from library compounds by a single “inert” structural component is described. This algorithm, the Hybrid Similarity Search, generates a similarity score based on matching both fragment ions and neutral losses. It employs...

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Published inAnalytical chemistry (Washington) Vol. 89; no. 24; pp. 13261 - 13268
Main Authors Moorthy, Arun S, Wallace, William E, Kearsley, Anthony J, Tchekhovskoi, Dmitrii V, Stein, Stephen E
Format Journal Article
LanguageEnglish
Published United States American Chemical Society 19.12.2017
Subjects
Algorithms
Chemical compounds
chemical derivatives
Chemistry
designer drugs
Drugs
Fragmentation
illicit drugs
Illicit Drugs - analysis
Ions
Ions - chemistry
Libraries
Mass spectrometry
Matching
moieties
Molecular Structure
Molecular Weight
Nearest-neighbor
Organic chemistry
Queries
Search algorithms
Search Engine
Similarity
Spectra
Tandem Mass Spectrometry
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ISSN0003-2700
1520-6882
1520-6882
DOI10.1021/acs.analchem.7b03320

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Summary:A mass spectral library search algorithm that identifies compounds that differ from library compounds by a single “inert” structural component is described. This algorithm, the Hybrid Similarity Search, generates a similarity score based on matching both fragment ions and neutral losses. It employs the parameter DeltaMass, defined as the mass difference between query and library compounds, to shift neutral loss peaks in the library spectrum to match corresponding neutral loss peaks in the query spectrum. When the spectra being compared differ by a single structural feature, these matching neutral loss peaks should contain that structural feature. This method extends the scope of the library to include spectra of “nearest-neighbor” compounds that differ from library compounds by a single chemical moiety. Additionally, determination of the structural origin of the shifted peaks can aid in the determination of the chemical structure and fragmentation mechanism of the query compound. A variety of examples are presented, including the identification of designer drugs and chemical derivatives not present in the library.
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ISSN:0003-2700
1520-6882
1520-6882
DOI:10.1021/acs.analchem.7b03320