| The main ingredient in edible oil is triacylglycerol(TAG),which is an important part of the diet.It can also be used as an auxiliary material in the preparation of medicines and is closely related to human health.Various combinations of fatty acids on the glycerol backbone and different TAG positional isomers make it many different structural changes.Therefore,the analysis of TAG components in edible oil is a challenging task.A high performance liquid chromatography(HPLC)method based on a porous graphite carbon column and n-octane-isopropanol mobile phase was established for the analysis of TAGs in edible oils,and the characteristic components of animal and vegetable oils were searched for adulteration identification.It is mainly divided into the following two parts:(1)Under the condition of ultraviolet detection,a high performance liquid chromatography analysis method with porous graphite carbon column(PGC)and a n-octane-isopropanol mobile phase was studied to separate TAGs in edible oils.The samples were separated by using a Hypercarb column(2.1 mm × 100 mm,5 μm)with n-octane-isopropanol(70:30,V/V)as mobile phase at a flow rate of 0.25 m L/min and at column temperature of 60oC,and detected at 215 nm.The experimental conditions on separation and detection were investigated.Then,TAGs in 7 vegetable oils and 5 animal fats were separated using selected experimental conditions.14 TAGs in corn oil,9 TAGs in olive oil,and 14 TAGs in sunflower oil,14 TAGs in soybean oil,15 TAGs in sesame oil,18 TAGs in peanut oil,17 TAGs in rapeseed oil,16 TAGs in chicken fat,17 TAGs in lard,12 TAGs in sheep fat,14 TAGs in beef tallow and 16 TAGs in goose fat were identified by combining with mass spectrometry detection.When analyzing chicken fat and tallow,the separation of 1-Stearin-2-Linolein-3-Palmitin(SLP)and 1-Stearin-2-Olein-3-Palmitin(SOP)from their respective positional isomers was achieved,showing that the method has the ability to separate TAG positional isomers.The established method was verified,and the LLL content in corn oil,rapeseed oil,sunflower oil,soybean oil,peanut oil,sesame oil and olive oil was separated and determined by the method.The method uses less-polluting mobile phase and better practicability to provide a valuable method for the analysis of TAGs and their isomers in edible oil.(2)A high performance liquid chromatography-mass spectrometry analysis method with porous graphite carbon columns(PGC)and a n-octane-isopropanol isocratic mobile phase was used to separate TAGs in edible oils.The samples we separated by using a Hypercarb column(2.1 mm × 100 mm,5 μm)with n-octane-isopropanol(70:30,V/V)as mobile phase at a flow rate of 0.25 m L/min and at column temperature of 60oC,and detected by APCI ionization-mass spectrometry.The characteristic component 1-Stearin-2-Palmitin-3-Olein(SPO)was found in lard as its characteristic component by using principal components analysis(PCA)and orthogonal partial least squares discriminant analysis(OPLS-DA)chemometrics method.The SPO was then applied for identification of adulteration of lard in soybean oil,corn oil and sunflower seed oil,and a minimum of 0.1% lard adulteration can be detected.In particular,SPO is prepared by high performance liquid chromatography and then quantified by 1H-NMR,which can be used as a standard sample for quantification.In order to compare the differenct kinds of edible oils,the similarity of high performance liquid chromatograms of soybean oil,corn oil and lard from their respective origins was also calculated through the similarity evaluation methodology of fingerprint for traditional Chinese medicine.The results show that the similarity of the three oil samples was greater than 97.2%,which shows that the same kind oil is high similarity,and above method is wide applicability for identifying adulteration of edible oils.The method provides an accurate and effective way for adulteration identification of adulterated lard(and waste cooking oils)in soybean oil,corn oil and sunflower oil. |
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