气相色谱法测定肠外营养用海豹油脂肪乳中主要脂肪酸的含量

目的：建立气相色谱法测定肠外营养用海豹油脂肪乳（20％）中各主要脂肪酸（fattyacid，FA），包括肉豆蔻酸、棕榈酸、棕榈油酸、油酸、花生酸、二十碳五烯酸（eicosapentaenoicacid，EPA）、二十二碳五烯酸（docosapentaenoicacid。DPA）、二十二碳六烯酸（docosahexaenoicacid，DHA）含量的方法。方法：比较三种甲酯衍生化方法的优劣，包括三氟化硼酯化法、甲醇－氢氧化钾室温酯化法和甲醇－氢氧化钠加热回流酯化法。气相色谱柱为HP—InnoWax柱（30m×0．320mm，0．25μm），采用FID检测器，标准曲线法定量。进样量1μl，分流比1：10。进样口温度220℃，检测器温度280℃，采用程序升温，起始温度155℃，保持1min，以25℃／min升到205℃，再以1℃／min升到235℃，最后以3℃／min升至250℃，保持5min。流速2．0ml／min。结果：从酯化操作过程和酯化效果来看，室温酯化法的效果较优。八种主要脂肪酸中，油酸含量最高（7．2％）、EPA含量最低（0．9％），其他6种脂肪酸含量介乎1．3％～5．8％之间。线性范围在0．009973-10．322mg／ml之间，平均回收率为98．4％～101．2％，RSD均小于2．0％（n=3）。结论：本法方便、准确、重现性好，可作为本制剂的质量控制方法。

Content determination of main fatty acid in Seal Oil Based Lipid Emulsion for parenteral nutrition by GC

Objective： To establish a GC method for determining the content of main fatty acid （FA） in seal oil based lipid emulsion （20%） for parenteral nutrition, including myristic acid, palmitic acid, palmitoleic acid, oleic acid, arachic acid, EPA, DPA, DHA. Methods： Find out the best method among three esterification methods, comprising boron trifluoride es- terification, methanol-potassium hydroxide esterification under room temperature and methanolsodium hydroxide under heated condition. HP-InnoWax column （30 m×0.320 mm, 0.25 μm） and FID were used, calibration curve method was employed to quantify. The injector and detector temperature were 220℃ and 280℃ respectively. The initial temperature was kept at 155℃ for 1 rain, then raised to 205℃ at the rate of 25℃/min, again to 235℃ at the rate of l%/min, finally to 250℃ at the rate of 3℃/min and maintained the temperature for 5 min. Flow rate was set at 2 ml/min. Results： Esterification under room temperature was considered to be the best method. Among the eight main FA, this emulsion had a highest content of oleic acid （7.2%） and the lowest content of EPA （0.9%）, the contents of the other six FA were between 1.3%- 5.8%, The linear range of all the main FA was between 0.009 973-10.322 mg/ml. The average recovery were all between 98.4%-101.2%, and RSD were all less than 2.0%（n=3）. Conclusion： The method is simple, accurate and reproducible. It may be adopted for the quality control of seal oil based lipid emulsion （20%） for parenteral nutrition.