植醇对牧草中脂肪酸测定的干扰及其消除

Elimination of Phytol Interference to the Determination of Fatty Acids in Herbage

通过对牧草脂肪酸的测定,分析气相色谱法直接碱催化甲酯化、碱皂化三氟化硼催化甲酯化2种前处理方法中植醇的干扰情况,优化碱皂化三氟化硼催化的试验条件.实验结果表明,在2种前处理方法中,植醇对牧草脂肪酸的测定均产生干扰,其中直接碱催化甲酯化法干扰较重.80℃是碱皂化三氟化硼催化甲酯化处理牧草的最优水浴温度,能完全去除植醇,且80℃时,脂肪酸的甲酯化效率最高.在添加量为100、500 mg/kg 2种水平中,5种脂肪酸甲酯的平均回收率在87.5%～94.1%之间,相对标准偏差(RSD)在2.0%～5.1%之间.改进的方法能消除植醇的干扰,其准确度和精密度能满足牧草脂肪酸测定要求.

The investigation of phytol interference was carried out by determining fatty acids in herbage using gas chromatography with methyl ester method by catalyzed potassium hydroxide and by saponification Boron trifluoridee,respectively.In order to eliminate the interference of phytol,the method catalyzed by saponification Boron trifluoridee was improved.The results indicated that the phytol interference to the determination of fatty acids in herbage by either of two methods all exist.The interference of phytol in the potassium hydroxide method was more serious than the other.Phytol can be eliminated by Boron trifluoridee-catalyzed after saponification at 80 ℃.And the esterification efficiency of fatty acid attained the highest value at 80 ℃ among five classes of temperatures.The spiked recoveries were in the range of 87.5%~94.1% at 100 mg/kg and 500 mg/kg levels;the relative standard deviations（RSD） were in the range of 2.0%~5.1%.The improved method is suitable for the determination of fatty acid in herbage and can eliminate the interference of phytol.