Fatty acid composition: Hydrogenated soybean oil mainly contains palmitic acid and stearic acid, and the remaining 6 fatty acids are impurities that need to be controlled to a limit. Among them, stearic acid and oleic acid are fatty acids with 18 carbon atoms. The retention time is relatively close, and it is not easy to separate. The detection method of the European Pharmacopoeia is extraction after saponification of potassium hydroxide and methanol, and reflux of 14% boron trifluoride methanol solution is not used. During the test, the test product is foamy after saponification of potassium hydroxide and methanol. and extraction difficulties. At present, the detection method adopted by the Chinese Pharmacopoeia is to use boron trifluoride as the esterification agent to determine the composition of fatty acids in hydrogenated soybean oil by gas chromatography and temperature programming. Results Eight kinds of fatty acids could be baseline separated within 20 minutes, with good linearity, precision and reproducibility. This method is simple and quick, and can be used for the determination of fatty acid composition in hydrogenated soybean oil.
Trans-fatty acid refined soybean oil is dominated by polyunsaturated fatty acids, the content of trans fatty acids is less, and most of them are trans octadecyl soybean oil polyene fatty acids; the content of polyunsaturated fatty acids in hydrogenated soybean oil is significantly reduced, and the content of trans fatty acids The content increased significantly, which was about 10 times of the trans fatty acid content in refined soybean oil, and most of them were trans-octadecene fatty acid. CP-Sil88 strong polar capillary column gas chromatography can be used for qualitative and quantitative analysis of cis, trans isomerism and position isomerism fatty acids in refined and hydrogenated soybean oil, and the baseline separation of the main cis and trans fatty acids has been achieved , and achieved good separation of fatty acids with various positional isomerisms
No preservatives and antioxidants were added to nickel-hydrogenated soybean oil, and nickel was used as a catalyst in the hydrogenation process. Therefore, the residual nickel should be controlled in the quality standard. Refer to the second method of the Chinese Pharmacopoeia Appendix IVD atomic absorption spectrophotometry standard addition method. Preparation of the test solution: Take 5.0 g of hydrogenated soybean oil, put it into a crucible, heat it slowly until it is charred, burn it at 600°C until it becomes white ash, cool it, wash the residue twice with dilute hydrochloric acid, 2 mL each time, to a volume of 25 mL. 241 measuring bottle, add 0.3mL nitric acid to dissolve, dilute with water to the mark. Preparation of control solution (main standard solution): Accurately measure standard nickel solution and dilute with water to 100 μg/L. Take 0.0, 1.0, 2.0, 3.0mL each and add 2.0mL of the test solution, and dilute with water to 10.0mL. The determination method can be determined by graphite furnace atomic absorption spectrometry, Zeeman background correction, and standard addition method. The drying time and ashing temperature are optimized. The operation is simple, the result is stable and accurate, and the sensitivity is high. It can effectively control the quality of the pharmaceutical excipient .