Hazel R. Mottram

Identification of triacylglycerol positional isomers present in vegetable oils by high performance liquid chromatography/atmospheric pressure chemical ionization mass spectrometry

High performance liquid chromatography in conjunction with atmospheric pressure chemical ionization mass spectrometry (HPLC/APCI-MS) enables the positional isomers of individual triacylglycerols in mixtures to be identified. Application of HPLC/APCI-MS to the analysis of soybean oil allowed thirty nine triacylglycerols and seven diacylglycerols to be positively identified. The compounds present were quantified and the distribution of fatty acids in the ‚-position calculated. This distribution compared favourably with that obtained using a more conventional regiospecific lipase degradation of the oil. A survey of the acylglycerol components of a range of vegetable oils (blackcurrant, blue poppy seed, evening primrose, extra virgin olive, hazelnut, maize and rapeseed) carried out using HPLC/APCI-MS is reported.

Structure analysis of triacylglycerol positional isomers using atmospheric pressure chemical ionisation mass spectrometry

Abstract Fragmentation of triacylglycerols by atmospheric pressure ionisation allows identification of positional isomers. The relative intensities of the [M-RCO 2 ] + ions provide information on the position of fatty acids within an ABC type triacylglycerol and enable ABA and AAB type molecules to be distinguished.

New Criteria for the Identification of Animal Fats Preserved in Archaeological Pottery

R.P. Evershed, H.R. Mottram, S.N. Dudd, S. Charters, A.W. Stott,G.J. LawrenceOrganic Geochemistry Unit, School of Chemistry, Cantock’s Close,University of Bristol, Bristol, BS8 1TS, UKA.M. GibsonClwyd-Powys Archaeological Trust, 7a Church Street, Welshpool Powys,SY21 7DL, UKA. ConnerCambridgeshire County Council Archaeology Unit, Fulbourne CommunityCentre, Haggis Gap, Fulbourne, Cambridge, CB1 5HD, UKP.W. BlinkhornOxford Archaeological Unit, Janus House, Osney Mead, Oxford, OX2 0ES, UKV. ReevesCentral Archaeological Services, English Heritage, Fort Cumberland,Fort Cumberland Road, Eastney, Portsmouth, PO4 9LD, UK

Regiospecific characterisation of the triacylglycerols in animal fats using high performance liquid chromatography-atmospheric pressure chemical ionisation mass spectrometry

High performance liquid chromatography-atmospheric pressure chemical ionisation mass spectrometry (HPLC-APCI MS) was applied to the characterisation of triacylglycerols (TAGs) in animal fats. The major TAGs in four fats (beef, chicken, lamb and pork) were identified and positional isomers assigned according to their APCI mass spectra. Beef and lamb fat TAGs were confirmed as containing higher proportions of saturated fatty acids compared with those of chicken and pork. HPLC-APCI MS was also shown to be of value in providing regiospecific information for the fatty acids in individual TAG species. For example, beef and lamb fat were shown to contain both cis- and trans-isomers of the 18:1 fatty acid, whilst chicken and pork contained only the cis-isomer. When the position of fatty acid substitution was determined from the APCI spectra, whilst the cis- 18:1 was predominantly found in the 2-position of the TAG, the trans-18:1 showed a preference for the 1/3-position. Similarly, it was confirmed that although the 2-position of beef, chicken and lamb fat TAGs was dominated by unsaturated fatty acids, in pork fat, a characteristically high proportion of palmitic acid was seen in this position. The TAGs identified compared well with those reported previously. The distributions of 2-position fatty acids seen in lamb and pork fat compared favourably with those obtained by the more traditional method of lipase degradation. Although the distributions for chicken and beef showed some discrepancies, these can be attributed to weaknesses in the quantification procedure or the specificity of the lipase. Overall, the technique of HPLC-APCI MS has been shown to be very powerful for the regiospecific analysis of animal fats.

Elucidation of the composition of bovine milk fat triacylglycerols using high-performance liquid chromatography-atmospheric pressure chemical ionisation mass spectrometry

Bovine milk fat triacylglycerols (TAGs) have been characterised using high-performance liquid chromatography-atmospheric pressure chemical ionisation mass spectrometry (HPLC-APCI-MS) and high-temperature gas chromatography-mass spectrometry (GC-MS). The complex nature of the fat meant that prefractionation was necessary to provide simpler fractions for more detailed molecular analyses. Silica thin-layer chromatography gave rise to two fractions, one of which contained predominantly butyric acid containing TAGs. Gel permeation chromatography (GPC) gave rise to 16 fractions, which were subsequently analysed using HPLC-APCI-MS. Twelve of the GPC fractions were also analysed by high-temperature GC-MS using a capillary column coated with a polarisable stationary phase. TAGs present in the fractions were correlated with those in the chromatogram of the whole milk fat through retention time comparison and the use of mass chromatograms. In total, 120 TAGs were identified.

A NEW MASS SPECTROMETRIC METHOD FOR THE REGIOSPECIFIC ANALYSIS OF TRIACYLGLYCEROLS IN EDIBLE OILS AND FATS

Edible fats and oils are mainly composed of complex mixtures of triacylglycerols (TAG). The position of fatty acid substitution on the glycerol backbone of a triacylglycerol (TAG) molecule is of considerable importance from a physiological1 and nutritional’ point of view. Consequently, in order to fully characterize a TAG molecule, it is necessary to know the constituent fatty acids and their position within the molecule. However, the ability to unambiguously identify positional isomers of individual TAGs, especially when they are components of complex natural mixtures, is a long standing problem in lipid chemistry.