Fingerprinting of traditionally produced red wines using liquid chromatography combined with drift tube ion mobility-mass spectrometry

Abstract

The characterization of wine via MS-based metabolic fingerprinting techniques remains a challenging undertaking due to the large number of phenolic compounds that cannot be confidently annotated and identified within analytical workflows. The combination of high performance liquid chromatography with low-field drift tube ion mobility time-of-flight mass spectrometry (HPLC × IMS-TOFMS) offers potential for the confident characterization and fingerprinting of wine using a metabolomics-type workflow. In particular, the use of collision cross section values from low-field drift tube IMS using nitrogen as drift gas (DTCCSN2) in addition to retention time and a high resolution mass spectrum for putative compounds allows rugged statistical assessment and identity confirmation using CCS libraries (<0.5% error) to be performed. In the present work, an HPLC × IMS-TOFMS platform has been utilized for the fingerprinting of 42 traditionally produced red wines emanating from the Republic of Macedonia. After establishing the reliability of DTCCSN2 as an identification point for wine metabolomics in both ionization modes, fingerprinting of wines according to grape variety was undertaken and a full dataset containing retention, accurate mass and DTCCSN2 values used to derive lists of compounds found to be statistically characteristic for each variety. Putative compounds were further assessed by assignment of in-source and post-drift mass fragments aligned according to retention time, drift time, and accurate mass providing up to seven identification points for a single compound when data from both positive and negative mode measurements are combined.