毛细管气相色谱测定食品中二十碳五烯酸和二十二碳六烯酸含量

Determination of EPA,DHA in food by capillary gas chromatography

目的建立毛细管气相色谱法测定油脂类食品、液体乳制品、粉末及固体状食品中二十碳五烯酸(EPA)和二十二碳六烯酸(DHA)的检测方法。方法样品经脂肪提取,氢氧化钾-甲醇溶液或三氟化硼乙醚甲醇溶液甲酯化,用色谱柱(DB-1701,30 m×0.32 mm,0.25μm;DB-88,100 m×0.25 mm,0.25μm)分离EPA和DHA,气相色谱氢火焰检测器分析,外标法定量。结果 EPA和DHA标准溶液在20μg/ml^400μg/ml浓度内呈良好的线性关系,相关系数>0.999,样品分别加入低、中、高3个浓度水平的EPA和DHA标准,加标回收率分别为86.8%~99.6%和87.9%~105.1%,6次重复测定RSD <10%,本方法 EPA和DHA的检出限分别为0.000 75 g/100 g^0.001 5 g/100 g和0.001 g/100 g^0.002 g/100 g,定量限分别为0.002 2 g/100 g^0.004 5 g/100 g和0.003 g/100 g^0.006 g/100 g。结论该方法可用于油脂类食品、液体乳制品、粉末及固体状食品中EPA和DHA的检测,操作简单、快速、准确。

A method was established for the determination of contents of EPA and DHA in grease food,liquid dairy product,and powder and solid food by capillary gas chromatography. Methods The samples were conducted for fat extraction and methylation of KOH-methanol solution or ethyl boron trifluoride-methanol solution. EPA and DHA were separated on chromatographic column ( DB-1701,30 m × 0. 32 mm,0. 25 μm;DB-88,100 m × 0.25 mm,0.25 μm),and then analyzed by gas chromatography with flame ionization detector ( FID),and quantified with external standard method. Results The linearity for EPA and DHA was good at concentration of 20 μg /ml-400 μg /ml ( r > 0. 999). The samples were added with EPA and DHA standards at low,medium and high concentration levels,respectively. The average spiked recovery were within 86. 8%-99. 6% and 87. 9%-105. 1%,with RSD < 10%( n = 6). The limits of detection ( LODs) of EPA and DHA were within 0. 000 75 g /100 g-0. 001 5 g /100 g and 0. 001 g /100 g-0. 002 g /100 g,and the limits of quantification ( LOQs) of EPA and DHA were within 0. 002 2 g /100 g-0. 004 5 g /100 g and 0. 003 g /100 g-0. 006 g /100 g. Conclusion It is suitable for the determination of EPA and DHA in grease food,liquid dairy product,and powder and solid food,and the procedure is simple,rapid and precise.