Selective detection triglycerides

The technical difficulties of making films which, both work and stay in place are immense. But now the breakthrough has happened, many other and more complex chemistries have been fixed on film. Film is available for urea, triglycerides and anylase in blood sera, and even ion selective electrodes have been adapted for the detection of metal ions such as Na +, K +, etc. in a single step. 

Although dietary lipids are mainly constituted of triglycerides (TG), long-chain fatty acids (LCFA more than 16 carbons) seem to be responsible for oral lipid perception. In a free-choice situation, rats have a weaker preference for TG and medium-chain fatty acids (8 to 14 carbons) than for LCFA (Tsuruta et al. 1999 Fukuwatari et al. 2003). This chemical selectivity is very tight, as LCFA derivatives, such as methyl LCFA, are not recognized (Tsuruta et al. 1999). The ability of rodents to detect LCFA specifically has also been confirmed with the conditioned taste aversion paradigm. It is noteworthy that both rats and mice can be conditioned to avoid specific LCFA (McCormack et al. 2006 Gaillard et al. 2008), with a submicromolar detection threshold (McCormack et al. 2006 Yoneda et al. 2007). 

The basic analytical requirement is to determine the level of a particular fatty acid in a complex mixture of fatty acids combined as triglycerides in an oil or fat. Hence the method must be based on a chromatographic separation of the fatty acids derived from the triglycerides, followed by a suitable detection system. In practical terms, therefore, the only analytical approaches are those based on the separation of the methyl esters of the fatty acids by variants of gas-liquid chromatography (GLC) and thin-layer chromatography (TLC). The degree of selectivity and sophistication of the chosen method will depend on the complexity of the sample. 

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