Analysis Of Triacylglvcerols In Edible Oil And The Hydrolyzate Of Acetonitrile By Gas Chromatography-mass Spectrometry

Edible oil is an indispensable energy source in human life,triglycerides are the main ingredient of edible oil.Due to the diversity of fatty acids,the types of triglycerides in edible oils are also varied.At present,there are problems of the adulteration of edible oil in the world,and the problem of gutter oil in China.Because the different edible oil contains different triglyceride,the edible oils can be identified and distinguished through the analysis of the composition of triglyceride.Gas chromatography-mass spectrometry(GC-MS)technique is an effective technique for the analysis of triglycerides.The further research of the GC-MS analysis method of triglyceride in edible oil is needed.At the same time for the hydrolysis of acetonitrile commonly used in high performance liquid chromatography(HPLC)mobile phase,hydrolysis of acetonitrile in the presence of trifluoroacetic acid were studied by GC-MS,and the effect of the hydrolysis products was studied by the UV detection of HPLC.In this thesis,the fatty acids and triglycerides in edible oils were separated and analyzed by GC-MS method,and the hydrolysis of acetonitrile under acidic conditions was also studied.It includes the following three parts:(1)The fatty acids composition of common edible oil(corn oil,sesame oil,peanut oil,rapeseed oil,etc)and home-made fried and boiled oil was analyzed.The effect of weak polar column and polar column on separation results are compared,the effects of experimental conditions on the separation and detection were investigated,the polarity PA-FFAP column(30m × 0.25m× 0.25um)was selected,the injection temperature was set as 250?,the column flow rate was 0.6mL/min,the interface temperature was 220?,the total time was 41 min.Qualitative by comparing with NIST08 standard mass spectra library and WILEY mass spectrometry database,the content of fatty acids in edible oils were obtained by normalization method.Results showed that the major fatty acids in vegetable oil were oleic acid and linoleic acid(accounting for more than 80%),Animal oils contain mainly palm acid,stearic acid and oleic acid(accounting for more than 60%).The composition and content of fatty acids in home-made fried oil and boiled oil did not change.(2)High temperature gas chromatography mass spectrometry(HT-GC/MS)analysis method for the determination of triglyceride in edible oil was studied.The effects of experimental conditions on the separation and detection were investigated,The MXT(?)-65TG(15m×0.25mm×0.10?m)column was selected.The composition of triglyceride in edible oil was classified according to the fragment ions([RCO]+,[RCO+74]+,[RCO+128]+,[M-RCOO]+)in the mass spectra of triglyceride combined with the mass spectra library.The results showed that there are 9 peaks in corn oil were triglyceride,19 kinds of triglycerides were identified,including PPL?PPO?PLL,POL,PSL,POO,POS?PLLn?POLn?PSLn?LLS?SSL?SOL?OOL?LLL?OOO?SOO?SSO?OLL.Triglycerides in home-made fried oil and boiled oil did not change significantly,but the content of diacylglycerol increased gradually.The content of lard in corn oil was as low as 10%could be detected by this method,animal oil could be detected in swill oil.(3)The hydrolysis of acetonitrile in the condition of adding trifluoroacetic acid was studied,and the effect of the hydrolysis product of acetonitrile was investigated by UV detection of high performance liquid chromatography.The acetonitriles with adding different content of trifluoroacetic acid and water were placed at different temperatures.Then the samples were directly subjected to GC-MS for analyzing after different time intervals.The results show that the concentration of the acetamide was gradually increased with the increase of time.The production of acetamide could be promoted by increasing the temperature and the content of trifluoroacetic acid.With acetonitrile-water(25:75,v/v)added 0.3%TFA as mobile phase,using L-Phenylalanine,4-Chloroaniline,D-(-)-mandelic acid,Quinine as samples,using a reversed-phase C18 column,the four kinds of material was separated by HPLC after the mobile phase was placed Oh,24h,48h.The results shows that the hydrolysis product of acetonitrile can affect the detection sensitivity of the four samples.