Triglyceride fats, HPLC analysis

Some methods which do not involve separation of the FFAs from the milk fat or the whole product have considerable appeal because of their simplicity. Sharma and Bindal (1987) exploited the property of methyl urea to complex triglycerides in producing methyl esters with BF3-methanol without first separating the FFAs from the fat, while Spangelo et al. (1986) were able to methylate FFAs in an acetonitrile extract of milk with methyl iodide in the presence of an anion exchange resin as catalyst. Miwa and Yamamoto (1990) derivatised the FFAs in milk and milk products for HPLC analysis by direct reaction with 2-nitrophenylhydrazine hydrochloride. 

Sample cleanup with an NP-HPLC column has been shown to be an efficient, robust way to separate triglycerides from organochlorine compounds for analysis in a wide range of fatty samples, such as milk, pork fat, animal feed, and cod liver (67). Complete fat-OCP separation is obtained in a small fraction volume. The method showed average recoveries of 80-110% in the concentration range of 1-510 /zg/kg, with relative standard deviations of less than 10%. The limits of detection ranged from 0.5 to 50 /ug/kg. The process can be monitored online with a UV detector. 

Sterol analysis, fatty acid analysis of the whole fat and of the acids at the 2-position, and triglycerides by GC, can be very useful in determining adulteration of and by animal fats. In the future HPLC of triglycerides is likely to provide an even better method for some purposes, but much more data need to be collected before this can be evaluated. 

Barron, L.J.R., Hierro, M.T.G., Santa-Maria, G. 1990. HPLC and GC analysis of the triglyceride composition of bovine, ovine and caprine milk fat. J. Dairy Res., 57, 517-526. 

HPLC has been used for measuring various compounds, for example, carbohydrates, vitamins, additives, mycotoxins, amino acids, proteins, triglycerides in fats and oils, lipids, chiral compounds, and pigments. Several sensitive and selective detectors such as ultraviolet-visible, FL, electrochemical, and diffractometric are available to utilize with HPLC depending on the compound to be analyzed. Various HPLC methods based on these detectors have been published for the measurement of vitamin E in biological and pharmaceutical samples and food products. Excellent literature reviews of HPLC based on various detectors in the analysis of vitamin E content in various matrices have been reported (Abidi, 2000 Aust et al., 2001 Ruperez et al., 2001 Lai and Franke, 2013). Table 19.5 reports several recent HPLC methods for the analysis of vitamin E and similar compounds in various matrices. 

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