Identification of Polymethylene-Interrupted Polyunsaturated Fatty Acids (PMI-PUFA) by Solvent-Mediated Covalent Adduct Chemical Ionization Triple Quadrupole Tandem Mass Spectrometry.
Anal Chem
; 92(12): 8209-8217, 2020 06 16.
Article
em En
| MEDLINE
| ID: mdl-32463662
ABSTRACT
Pine nuts and other edible gymnosperm seeds contain unusual, bioactive polymethylene-interrupted polyunsaturated fatty acids (PMI-PUFAs), a subset of nonmethylene-interrupted PUFA with (-CH2-)n≥2 intervening between double bonds. Conventional methods for structure elucidation of PMI-PUFAs require special derivatization risking rearrangement artifacts. Here we introduce a facile solvent-mediated (SM) covalent adduct chemical ionization (CACI) system modified with a triple quadrupole MS, which distinguishes PMI-PUFAs from their analogues in direct methyl ester form. The prominent Δ5 desaturated PMI-PUFAs exhibit characteristic fragmentation at C6-7 to yield ω diagnostic ions and share their fragmentation pattern with normal methylene interrupted PUFAs for the α diagnostic ion. H⢠transfer upon CID dissociation of PMI-PUFAs was found to be dependent on the relative position of isolated lone double bonds and cleavage points. Ginkgo and five species of pine nuts were characterized for their unique Δ5 fatty acid profile, without the need for chemical standards.
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Ácidos Graxos Insaturados
Tipo de estudo:
Diagnostic_studies
/
Guideline
/
Prognostic_studies
Idioma:
En
Ano de publicação:
2020
Tipo de documento:
Article