Free NIST GC-MS Software Lab for Universities: Part 9: 58,456 Additional Reference Spectra for NIST Demo Search

Significance of the Topic

Mass spectrometry identification relies on comprehensive reference libraries. Expanding free libraries enables teaching labs and researchers to tackle real-world samples with broader compound coverage.

Objectives and Study Overview

This work integrates five public GC–MS libraries into the NIST Demo Search software for educational use. It provides open access to 58 456 additional electron ionization spectra and 34 933 chemical structures. Study steps include library origin review, format conversion, quality assessment, software installation, and search configuration.

Methodology and Instrumentation

The study employs the Lib2NIST utility to convert SDF-based libraries into NIST MS formats. Libraries are placed in the Demo Search "MSSEARCH" directory, followed by index file generation for spectrum, structure, hybrid, and InChIKey searches. Although GC–MS hardware is not specified, the NIST Demo Search software mimics standard EI-GC-MS data processing workflows.

Main Results and Discussion

Integration yields in total approximately 60 829 EI spectra and 37 306 structures across six libraries:

• Mainlib: 2 373 spectra (very high quality, NIST standard)
• SWGDrug: 3 598 spectra (drug-related, good quality)
• Cayman: 2 262 spectra (novel psychoactive substances, good quality)
• Misc_lib: 20 049 spectra (Kodak collection and internet sources, ~95% quality for Kodak subset)
• MONA: 18 914 spectra (crowd-sourced metabolome entries, variable derivative annotations)
• Black Book (BB): 13 633 six-peak indices (ASTM and Eastman data, useful for low-molecular-weight compounds)

Quality ranking (highest to lowest): mainlib > BB > SWGDrug/Cayman > Misc_lib > MONA. MONA exhibits derivative annotation issues affecting structure searches. Detailed installation ensured visibility of index files and library selection for both spectrum and structure searches.

Benefits and Practical Applications

By expanding the Demo Search database, users gain improved compound coverage for forensic, environmental, food safety, and metabolomic studies. Teaching laboratories can simulate diverse analytical scenarios. Hybrid search and structural search capabilities support confident identification and verification of unknowns.

Future Trends and Potential Applications

Future developments may include cloud-based library sharing, automated quality scoring, integration of tandem mass spectra, and AI-driven spectral interpretation. Community-driven updates will keep public repositories current and broaden analytical scope.

Conclusion

The addition of free public libraries into NIST Demo Search enhances educational and research workflows by providing extensive spectral coverage. Proper conversion, indexing, and quality awareness are crucial for reliable GC–MS identification results.