Submitted to: Rapid Communications in Mass Spectrometry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/6/2001
Publication Date: N/A
Citation: Interpretive Summary: Amounts and types of the components called triglycerides of the fat portion of food products are important. The triglycerides of the fat portion have an important effect on melting range, oxidative stability and texture of the finished food product. Also, the triglycerides are important for nutritional and health value. Secondly, when the fat portion begins to degrade during shelf storage or during frying of foods, potentially harmful products can be produced. It is important to identify the degradation products so that modifications can be made in the fat portion to reduce or eliminate the degradation. We presented in this work a technique to learn about the amounts and types of these triglycerides and their degradation products. This technique is called high-performance liquid chromatography, which separates the different triglycerides based on the length and unsaturation of the fatty acids and any functional groups they contain. After separation, the amounts and identities of the triglycerides and their degradation products can be determined as they are passed simultaneously through a detector called a quadrupole mass spectrometer equipped with a device called an atmospheric chemical ionization source and through a detector called an ion trap mass spectrometer equipped with a device called an electrospray source. This is a new method, which determines accurately the triglyceride and triglyceride degradation product composition of edible fats. This work should assist formulation of improved food products for the consumer.
Technical Abstract: Two mass spectrometers, in parallel, were employed simultaneously for analysis of triacylglycerols in canola oil, for analysis of triolein and trilinolein oxidation products, and for analysis of triacylglycerol position isomers separated using reversed-phase high performance liquid chromatography. A triple quadrupole mass spectrometer operated in Q3 mode was interfaced via an atmospheric pressure chemical ionization (APC) interface to two reversed-phase liquid chromatographic columns in series. An ion trap mass spectrometer was coupled to the same two columns using an electrospray ionization (ESI) interface, with ammonium formate added as electrolytee. Electrospray ionization mass spectrometry (MS) under these conditions produced abundant ammonium adduct ions from triacylglycerols, which were then fragmented to produce MS/MS mass spectra and then fragmented further to produce MS/MS/MS mass spectra. MS/MS of the ammoniated molecular ions produced diacylglycerol fragment ions, and additional fragmentation (MS/MS/MS) produced [RCO]+ (acylium) ions, [RCOO+58]+ ions, and other related ions which allowed assignment of individual acyl chain identities. APCI-MS of triacylglycerol oxidation products produced spectra nearly identical to those reported before using APCI-MS. ESI-MS of triacylglycerol oxidation products produced abundant ammoniated molecular ions, even for those molecules which previously produced little or no molecular ion under APCI-MS condictions (such as hydroperoxides). Fragmentation (MS/MS) of the ammoniated molecular ions produced results similar to those obtained by APCI-MS.