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 ionisa tion mass spectrometry (HPLC-APCI MS) was applied to the characterisation o f triacylglycerols (TAGs) in animal fats. The major TAGs in four fats (beef , chicken, lamb and pork) were identified and positional isomers assigned a ccording to their APCI mass spectra. Beef and lamb fat TAGs were confirmed as containing higher proportions of saturated fatty acids compared with tho se of chicken and pork. HPLC-APCI MS was also shown to be of value in provi ding regiospecific information for the fatty acids in individual TAG specie s. 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 fr om the APCI spectra, whilst the cis-18:1 was predominantly found in the 2-p osition 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 posit ion. 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 deg radation. Although the distributions for chicken and beef showed some discr epancies, these can be attributed to weaknesses in the quantification proce dure 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 ani mal fats.