Analytical Instrument Documents

MSTips No. 538

Oysters are known for their rich umami taste and distinctive aroma.Their flavor profiles are important factors in quality evaluation. Various volatile compounds contribute to oyster aroma. Among them, (Z)-1,5-octadien-3-ol, also known as oyster alcohol, is one of the main compounds responsible for the distinctive aroma of oysters (Fig. 1). This compound is not registered in the NIST database (DB).

In 2021, JEOL released msFineAnalysis iQ, integrated qualitative analysis software compatible with gas chromatograph quadrupole mass spectrometer (GC-QMS) data. This software enables more reliable qualitative analysis by combining NIST DB search results obtained from electron ionization (EI) data with molecular mass information obtained from soft ionization (SI) data.

However, because conventional integrated qualitative analysis relies on NIST DB searches, it has been difficult to estimate the structures of compounds not registered in the DB. As a solution for the structural analysis of such compounds, JEOL developed msFineAnalysis IQ Ver.3. In addition to integrated qualitative analysis combining EI and SI data, this software includes an AI Structure Analysis function based on deep learning. By utilizing an AI library containing predicted EI mass spectra, it is possible to estimate the structures of compounds not registered in the NIST DB more efficiently (MSTips No. 535).

Furthermore, a newly developed EI/ chemical ionization (CI) combination ion source eliminates the need to replace the ion source or vent the system, enabling continuous acquisition of both EI and CI data. In this MSTips, we report a case study of AI Structure Analysis of oyster aroma compounds using HS-SPME-GC-QMS and msFineAnalysis IQ Ver.3. Molecular mass information obtained from the CI data was used to evaluate whether the structure reported for oyster alcohol, 1,5-octadien-3-ol, could be proposed as a candidate structure by AI Structure Analysis.