Study On Analysis Of Fatty Acid Composition In Food And Drug By Gas Chromatography/mass Spectrometry With On-line Pyrolytic Methylation Technique

On-line pyrolytic methylation-gas chromatography is particularly suitable for the analysis of complex samples containing fatty acids,polyhydric alcohols and esters.Samples mixed with methylation reagent such as tetramethylammonium hydroxide(TMAH)were injected into the pyrolyzer at a high temperature,followed by gas chromatography analysis.The fatty acids and esters were converted into their corresponding methyl esters.In this work,the on-line pyrolytic methylation-gas chromatography technique was applied in the analysis of fatty acid composition in food and drug.In the first chapter,the history,the chemical mechanism,the devices and the advantages and shortages of on-line pyrolytic methylation technique were briefly described.The applications of this method to analysis of lipids,natural products,biomacromolecules and synthetic polymers were discussed.In the second chapter,a method of on-line pyrolytic methylation-gas chromatography was developed for the analysis of fatty acid composition in cottonseed.On-line pyrolytic methylation of cottonseed samples at 350 ? in the presence of trimethylsulfonium hydroxide(TMSH)allowed analysis of fatty acids as their corresponding methylation esters.The main fatty acids were myristic acid(C14:0),palmitoleic acid(C16:1),palmitic acid(C16:0),linoleic acid(C18:2),oleic acid(C18:1),stearic acid(C18:0),arachidic acid(C20:0)and docosanoic acid(C22:0).The content of unsaturated fatty acid varied from 66.30-72.54 %,and the content of linoleic acid varied from 43.20-53.61 %.The relative standard deviations of the fatty acids were less than 10 %(n=5).The fatty acid composition in the cottonseed samples from different growing places and different edible oil samples were compared by statistical analysis.The results showed that the fatty acid composition in cottonseed samples from different regions was similar.It was closest to the corn oil,and the similarity was between 0.960-0.992.Cottonseed oil had a high nutritional value as edible oil.The fatty acids can serve as raw industrial material if separated from cottonseed oil.The on-line pyrolytic methylation-gas chromatography was a simple,rapid and accurate method for the analysis of fatty acid composition in cottonseed.In the third chapter,a method of on-line pyrolytic methylation-gas chromatography was developed for the analysis of fatty acid composition in polysorbate 80.Fatty acids in polysorbate 80 were converted into their corresponding methyl esters in the presence of trimethylsulfonium hydroxide(TMSH)with a vertical microfurnace pyrolyzer at 300 ?.The polysorbate 80 samples and methylation reagent were mixed before injection.Three samples of pharmaceutical grade and three samples of non-pharmaceutical grade were analyzed.The results showed that the fatty acid composition in the samples of pharmaceutical grade met the Chinese Pharmacopoeia requirements with the amount of oleic acid(18:1)varying from 74.4 to 89.3 %,and the fatty acid composition in the samples of non-pharmaceutical grade did not meet the Chinese Pharmacopoeia requirements with the amount of oleic acid varying from 62.0 to 63.5 %.The results obtained by this method were consistent with those obtained by off-line methylation.The on-line pyrolytic methylation-gas chromatography was a simple,rapid and accurate method for the analysis of fatty acid composition in polysorbate 80.In the last chapter,the main results obtained from this work were summarized.The problems found in this work and the possible future trends in this field were also discussed.