Fatty Acid Profiles Of Chinese Human Milk In Different Lactation Period By GC-MS

Human Lipidomics focuses on comprehensive analysis of lipids in human milk, mainly through improvement of extraction of human milk samples, separation methods and the development of new analytical identification techniques, with special emphasis on preparation technology of human milk lipid sample and advanced equipment, such as a mass spectrometer in combination, in order to achieve quick and high throughput analysis. Currently, it is common to report about human milk fatty acid analysis, but research about human milk lipidomics has not yet been found. Since the composition of human milk lipids is complex, the present study focus on the glycerides of fatty acids in human milk, and provide a comprehensive understanding of fatty acid glyceride as well as important data for further comprehensive study of Chinese human milk lipidomics.In this study, Chinese human colostrum, transitional milk and mature milk are used, through chloroform-methanol ultrasonic assisted extraction, total lipids in human milk was extracted. The glycerides are separated from extracted human lipids by solid phase extraction. By improving and optimizing the way to derivate fatty acids, as well as fully derivate the fatty acid glyceride, GC-MS was used in human milk samples in order to analyze the composition and content changes of glycerides of fatty acids in Chinese human colostrum, transitional milk and mature milk.The main research work and conclusions are as followed:(1) Comparing the three extraction methods, chloroform-methanol ultrasonic assisted extraction method was selected and by optimizing the ultrasonic output power and ultrasonic time parameters, the results showed that:when the ultrasonic output power is150W, ultrasonic extraction time is10min, the extraction rate of human milk lipids reaches the highest.(2) The fatty acid derivative methods has been improved and conditions are optimized. The optimal reaction time is22min and the reaction temperature is81.5℃, KOH-methanol was added in an amount of2.3mL, BF3-methanol is1mL. Under such conditions, fatty acids from human milk can be fully derivatized.(3) GC-MS method for the study, in a certain concentration range, a linear relationship of the method, recovery and precision for analysis study found that within5～600μg/mL range, concentration and formed by GC-MS molecular ion peak response showed good linearity and recoveries and good precision. Show that the method is suitable for the analysis of fatty acids.(4) GC-MS was used to analyze fatty acid methyl ester glycerides in human colostrum, transitional milk, and mature milk. Through scanning the characteristic ions of fatty acid methyl ester and comparing with ion mass spectrometry database to obtain a comprehensive analysis of glycerides of fatty acids in human milk, in order to get mass spectrum of glyceride methyl ester fatty acids composition. Compared with foreign studies, it is found that the optimal method is capable of providing a more comprehensive way to analyze fatty acids, which indicates GC-MS studies of human milk can be more accurate.