Tentative identification and quantification of TAG core aldehydes as dinitrophenylhydrazones in autoxidized sunflowerseed oil using reversed-phase HPLC with electrospray ionization MS.
The molecular species of TAG core aldehydes (aldehydes still esterified to parent molecules) were detected and quantified in dietary-quality sunflowerseed oil autoxidized for 0-18 d at 60 degrees C in the dark. The analyses were performed by reversed-phase HPLC with UV (358 nm) absorption or light scattering and electrospray ionization-MS (ESI/MS) detection following preparation of the dinitrophenylhydrazone derivatives. Aldehyde production, as estimated by UV and ESI/MS, increased gradually over the 18-d period following a rapid initial destruction of the core aldehydes accumulated during storage of the commercial oil at 10 degrees C for 3 mon. The contents of hydroperoxides and hydroperoxide core aldehyde combinations were estimated to account for about 5% of total TAG, quantified as area in the chromatographic trace, after 18 d of autoxidation as estimated by an evaporative light scattering detector (ELSD). The major species of core aldehydes were tentatively identified as 9-oxononanoyl (70%)-, 12-oxo-9,10-epoxydodecenoyl (10%)-, and 13-oxo-9,11-tridecadienoyl (5%)-containing acylglycerols, plus smaller amounts of simple and mixed chain-length dialdehydes, and hydroxy and epoxy monoaldehyde-containing acylglycerols (15% of total). Quantitatively, the core aldehydes made up 2-12 g/kg of oil by UV detection and 2-9 g/kg of oil by ESI/MS detection, whereas the hydroperoxides measured in the unreduced state by HPLC with ELSD were estimated at 200 g/kg after 18 d of autoxidation. The major hydroperoxides of sunflowerseed oil were as previously identified.
Sjövall
Olli
O
Banting and Best Department of Medical Research, University of Toronto, Canada M5G 1L6.
Kuksis
Arnis
A
Kallio
Heikki
H
D000447:Aldehydes / Q000032:analysis / Q000302:isolation & purification* / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D008054:Lipid Peroxides / Q000378:metabolism; D021241:Spectrometry, Mass, Electrospray Ionization; D014280:Triglycerides / Q000032:analysis / Q000302:isolation & purification* / Q000378:metabolism
D000447:Aldehydes; D008054:Lipid Peroxides; D014280:Triglycerides