Automatic Assignment of Molecular Ion Species to Elemental Formulas in Gas Chromatography/Methane Chemical Ionization Accurate Mass Spectrometry
Gas chromatography–mass spectrometry (GC-MS) usually employs hard electron ionization, leading to extensive fragmentations that are suitable to identify compounds based on library matches. However, such spectra are less useful to structurally characterize unknown compounds that are absent from libra...
| Main Authors: | , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2023-08-01
|
| Series: | Metabolites |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2218-1989/13/8/962 |
| _version_ | 1797583846212894720 |
|---|---|
| author | Shunyang Wang Luis Valdiviez Honglian Ye Oliver Fiehn |
| author_facet | Shunyang Wang Luis Valdiviez Honglian Ye Oliver Fiehn |
| author_sort | Shunyang Wang |
| collection | DOAJ |
| description | Gas chromatography–mass spectrometry (GC-MS) usually employs hard electron ionization, leading to extensive fragmentations that are suitable to identify compounds based on library matches. However, such spectra are less useful to structurally characterize unknown compounds that are absent from libraries, due to the lack of readily recognizable molecular ion species. We tested methane chemical ionization on 369 trimethylsilylated (TMS) derivatized metabolites using a quadrupole time-of-flight detector (QTOF). We developed an algorithm to automatically detect molecular ion species and tested SIRIUS software on how accurate the determination of molecular formulas was. The automatic workflow correctly recognized 289 (84%) of all 345 detected derivatized standards. Specifically, strong [M − CH<sub>3</sub>]<sup>+</sup> fragments were observed in 290 of 345 derivatized chemicals, which enabled the automatic recognition of molecular adduct patterns. Using Sirius software, correct elemental formulas were retrieved in 87% of cases within the top three hits. When investigating the cases for which the automatic pattern analysis failed, we found that several metabolites showed a previously unknown [M + TMS]<sup>+</sup> adduct formed by rearrangement. Methane chemical ionization with GC-QTOF mass spectrometry is a suitable avenue to identify molecular formulas for abundant unknown peaks. |
| first_indexed | 2024-03-10T23:44:46Z |
| format | Article |
| id | doaj.art-94c9ebf100014937b404c67408ca580a |
| institution | Directory Open Access Journal |
| issn | 2218-1989 |
| language | English |
| last_indexed | 2024-03-10T23:44:46Z |
| publishDate | 2023-08-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Metabolites |
| spelling | doaj.art-94c9ebf100014937b404c67408ca580a2023-11-19T02:09:31ZengMDPI AGMetabolites2218-19892023-08-0113896210.3390/metabo13080962Automatic Assignment of Molecular Ion Species to Elemental Formulas in Gas Chromatography/Methane Chemical Ionization Accurate Mass SpectrometryShunyang Wang0Luis Valdiviez1Honglian Ye2Oliver Fiehn3Department of Chemistry, University of California, Davis, CA 95616, USAWest Coast Metabolomics Center, University of California, Davis, CA 95616, USAWest Coast Metabolomics Center, University of California, Davis, CA 95616, USAWest Coast Metabolomics Center, University of California, Davis, CA 95616, USAGas chromatography–mass spectrometry (GC-MS) usually employs hard electron ionization, leading to extensive fragmentations that are suitable to identify compounds based on library matches. However, such spectra are less useful to structurally characterize unknown compounds that are absent from libraries, due to the lack of readily recognizable molecular ion species. We tested methane chemical ionization on 369 trimethylsilylated (TMS) derivatized metabolites using a quadrupole time-of-flight detector (QTOF). We developed an algorithm to automatically detect molecular ion species and tested SIRIUS software on how accurate the determination of molecular formulas was. The automatic workflow correctly recognized 289 (84%) of all 345 detected derivatized standards. Specifically, strong [M − CH<sub>3</sub>]<sup>+</sup> fragments were observed in 290 of 345 derivatized chemicals, which enabled the automatic recognition of molecular adduct patterns. Using Sirius software, correct elemental formulas were retrieved in 87% of cases within the top three hits. When investigating the cases for which the automatic pattern analysis failed, we found that several metabolites showed a previously unknown [M + TMS]<sup>+</sup> adduct formed by rearrangement. Methane chemical ionization with GC-QTOF mass spectrometry is a suitable avenue to identify molecular formulas for abundant unknown peaks.https://www.mdpi.com/2218-1989/13/8/962chemical ionizationquadrupole time-of-flightcompound identification |
| spellingShingle | Shunyang Wang Luis Valdiviez Honglian Ye Oliver Fiehn Automatic Assignment of Molecular Ion Species to Elemental Formulas in Gas Chromatography/Methane Chemical Ionization Accurate Mass Spectrometry Metabolites chemical ionization quadrupole time-of-flight compound identification |
| title | Automatic Assignment of Molecular Ion Species to Elemental Formulas in Gas Chromatography/Methane Chemical Ionization Accurate Mass Spectrometry |
| title_full | Automatic Assignment of Molecular Ion Species to Elemental Formulas in Gas Chromatography/Methane Chemical Ionization Accurate Mass Spectrometry |
| title_fullStr | Automatic Assignment of Molecular Ion Species to Elemental Formulas in Gas Chromatography/Methane Chemical Ionization Accurate Mass Spectrometry |
| title_full_unstemmed | Automatic Assignment of Molecular Ion Species to Elemental Formulas in Gas Chromatography/Methane Chemical Ionization Accurate Mass Spectrometry |
| title_short | Automatic Assignment of Molecular Ion Species to Elemental Formulas in Gas Chromatography/Methane Chemical Ionization Accurate Mass Spectrometry |
| title_sort | automatic assignment of molecular ion species to elemental formulas in gas chromatography methane chemical ionization accurate mass spectrometry |
| topic | chemical ionization quadrupole time-of-flight compound identification |
| url | https://www.mdpi.com/2218-1989/13/8/962 |
| work_keys_str_mv | AT shunyangwang automaticassignmentofmolecularionspeciestoelementalformulasingaschromatographymethanechemicalionizationaccuratemassspectrometry AT luisvaldiviez automaticassignmentofmolecularionspeciestoelementalformulasingaschromatographymethanechemicalionizationaccuratemassspectrometry AT honglianye automaticassignmentofmolecularionspeciestoelementalformulasingaschromatographymethanechemicalionizationaccuratemassspectrometry AT oliverfiehn automaticassignmentofmolecularionspeciestoelementalformulasingaschromatographymethanechemicalionizationaccuratemassspectrometry |