Identification of new, very long-chain polyunsaturated fatty acids in fish by gas chromatography coupled to quadrupole/time-of-flight mass spectrometry with atmospheric pressure chemical ionization

• Published in: Analytical and bioanalytical chemistry 2021-02, Vol.413 (4), p.1039-1046
• Main Authors: Serrano, Roque, Navarro, Juan Carlos, Portolés, Tania, Sales, Carlos, Beltrán, Joaquín, Monroig, Óscar, Hernández, Félix
• Format: Article
• Language: English
• Subjects: Analysis; Analytical Chemistry; Atmospheric pressure; Biochemistry; Bream; Characterization and Evaluation of Materials; Chemical properties; Chemistry; Chemistry and Materials Science; Chromatography; Eye (anatomy); Fatty acids; Fish; Fish farms; Food Science; Gas chromatography; Gonads; Identification and classification; Ionic mobility; Ionization; Ions; Laboratory Medicine; Lipids; Low concentrations; Mass spectrometry; Mass spectroscopy; Methods; Molecular chains; Monitoring/Environmental Analysis; Perciformes; Physiological aspects; Polyunsaturated fatty acids; Quadrupoles; Research Paper; Scientific imaging; Spectroscopy; Time-of-flight mass spectrometry; Unsaturated fatty acids; Vertebrates
• ISSN: 1618-2642; 1618-2650
• DOI: 10.1007/s00216-020-03062-0

The characterization of very long-chain (>C24) polyunsaturated fatty acids (VLC-PUFAs), which are essential in the vision, neural function, and reproduction of vertebrates, is challenging because of the lack of reference standards and their very low concentrations in certain lipid classes. In this research, we have developed a new methodology for VLC-PUFA identification based on gas chromatography coupled to quadrupole/time-of-flight mass spectrometry with an atmospheric pressure chemical ionization source (GC-APCI-QTOF MS). The mass accuracy attainable with the innovative QTOF instrument, together with the soft ionization of the APCI source, provides valuable information on the intact molecule, traditionally lost with electron ionization sources due to the extensive fragmentation suffered. We have identified, for the first time, VLC-PUFAs with chains up to 44 carbons in eyes, brain, and gonads of gilthead sea bream, a commercially important fish in the Mediterranean. The added value of ion mobility-mass spectrometry (IMS), recently developed in combination with GC-QTOF MS, and the contribution of the collisional cross section (CCS) parameter in the characterization of novel VLC-PUFAs (for which reference standards are not available) have been also evaluated. The methodology developed has allowed assessing qualitative differences between farmed and wild fish, and opens new perspectives in a still scarcely known field of research.