| Long-chain polyunsaturated fatty acids(LC-PUFAs) play a central role in the normal development and functioning of the brain and human immunity system, such as arachidonic acid, eicosapentaenoic acid and docosahexaenoic acid. They have a significant effect on preventing of heart disease, hypertension, inflammation, and even some cancers. Fatty acids can be classified as sn-1, sn-2 and sn-3 according to their positions on the glycerol backbone, which are divided into two types, one is α(sn-1, 3) position, It has been reported that the distribution position of FA on the glycerol backbone(sn-1, 2 or 3) have a significant impact on the property of TAG on digestion and absorption. However, the position is closely related to the varieties and the sources of fats and oils.Because of the longer carbon chain, the more number of double bonds and complex structure, the retention behaviors of LC-PUFAs TAGs on the liquid chromatography column are different compared with TAGs consist of low-medium chain FAs with relatively low DB number. Thus, the conventional analysis method of TAGs with low-medium chain FAs with relatively low DB number isn’t suitable for separating and identifing LC-PUFAs TAGs.This project focus on the development of the new method for the efficient separation and analysis of LC-PUFAs TAGs complex compounds. Firstly, florisil extraction cartridge and NH2 extraction cartridge were selected to purification the hydrolysis products of five different kinds of oils. Qualitative and quantitative analysis of sn-2 position fatty acid were realized by GC with a FFAP capillary column to research the distribution characteristics of sn-2 fatty acids in five kinds of oils. In order to further study the species of long chain polyunsaturated triglyceride in oils, We developed a technology platform using liquid chromatography coupled with tandem mass spectrometry with a PAH column. The PAH packing is a polymeric C18 bonding with 14% of carbon loading. The polymeric C18 stationary phase in PAH column could provide hydrophobic interactions. In addition, it has an ability to recognize the structural differences between TAG positional isomers pairs. This method was successfully applied for the profiling of LC-PUFA TAGs in seal oils. The major results are as follows:1. Total fatty acids and the sn-2 position fatty acids in plant oil, microbialing oil, marine animals oil and fish oil were investigated. The results showed that the sn-2 position fatty acids in plant oil are mainly medium- and long-chaingunsaturated fatty acids, in microbial oil, Algal Oil and Marine animals oil are mainly saturated fatty acids, and in fish oils are mainly long chain polyunsaturated fatty acids.2. Chromatographic behaviors of PAH column were investigated. PAH column has a “slot model” and could provide hydrophobic interactions. In PAH-HPLC, TAGs are commonly resolved according to the numbe of double bonds, with retention increasing as the number of double bonds decreases. PAH column exhibited much higher selectivity for the separation of LC-PUFA TAGs by comparing with the traditional C18 column. What’s more, the polymeric C18 stationary phase in PAH column has an ability to recognize the structural differences between triacylglycerol positional isomers pairs.3. A method for profiling LC-PUFA TAGs in oils using silver ion solid-phase extraction(Ag-SPE) methods coupled with atmospheric pressure chemical ionization(APCI) mass spectrometry with a PAH column was developed. This system was applied for the profiling of polyunsaturated TAGs in seal oils. In total, a number of 113 polyunsaturated triacylglycerols with 4–9 double bonds, consisting of 8 pairs of ABA/AAB type and 21 pairs of ABC/BCA type of polyunsaturated triacylglycerol positional isomer pairs, were recognized. This method provides a time consuming analytical technique and a significantly potential application on polyunsaturated TAGs profiling of marine lipids or any oils enriched in long chain polyunsaturated acids. |
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