Establishing an atmospheric pressure gas chromatography-MS (APGC-MS) based metabolomics platform

Metabolomics has become a powerful tool to study biological processes in organisms and to identify metabolites and Gas chromatography coupled with mass spectrometry (GCMS) is a well-established analytical approach in metabolomics. The most widely used ionization technique in GCMS is electron ionization (EI), which produces library searchable spectra dominated by fragments. The molecular ion in EI spectrum is often of very low abundance or absent. Many plant terpenoids have same molecular formula and shows matching fragmentation pattern when using EI, therefore any minor variation in the relative abundances of the masses in a spectrum lead to a false positive hit in NIST. Also lack of molecular ion information can give incorrect compound identification, if using spectral matching alone. Alternative approaches, such as the chemical ionization (CI), can be optimized to provide a molecular ion with reduced fragmentation, but with the serious drawback of a major loss of the sensitivity. Atmospheric pressure gas chromatography coupled with mass spectrometry (APGC-MS) is an ionization technique that generates a spectrum conserving the molecular ion species with minimal fragmentation; additionally the system offers high mass accuracy, which is extremely useful in structure elucidation of unknown volatiles. We are establishing Atmospheric Pressure Gas Chromatography-MS (APGC-MS) Based Metabolomics Platform for volatile plant metabolites; primary results using Grape as a model sample are presented