本文开发了固相萃取-HPLC柱后氧化衍生荧光法测定运动营养食品中叶酸含量的方法。分别考察了沉淀蛋白法、酶解蛋白法及固相萃取法的样品前处理方式及流动相的优化条件,最终选择反相弱阴离子交换Strata-X-AW固相萃取小柱纯化,Venusil MP C18色谱柱分离,柱后衍生仪氧化衍生(5%过二硫酸钾溶液),以50 mmol磷酸二氢钾(pH3.5):乙腈=90:10(V/V)为流动相,再经荧光检测器进行检测。结果表明,在0.232~2.318 μg/mL范围内方法线性良好,R2=0.9971,进样量为10 μL,方法的仪器定量限为0.0774 μg/mL,灵敏度足以满足运动营养食品中叶酸的检测需要,方法回收率在96.98%~100.50%之间,标准品、样品溶液在8 h内稳定。本方法很好地解决复杂基质运动营养食品中叶酸的提取、净化除杂等问题。操作方便快捷,结果准确,线性范围广,灵敏度高,重现性、专属性、回收率及稳定性较为满意,能够满足日常运动营养食品中叶酸含量检测的需求。
A method for the determination of folic acid in sports nutrition food by solid phase extraction and HPLC post column oxidation derivative fluorescence was developed. The pretreatment methods of precipitated protein method,enzymolysis protein method and solid phase extraction columns were investigated respectively,and the optimized conditions of mobile phase were obtained. Weak reversed-phase anion-exchange Strata-X-AW solid-phase extraction columns were used for purification,and Venusil MP C18 columns were used for separation. Post-column derivatization instrument for oxidative derivatization(5% potassium persulfate solution),and 50 mmol potassium dihydrogen phosphate(pH3.5):acetonitrile=90:10 (V/V)was the final choice of mobile phase,and then the content of folic acid was detected by fluorescence detector. The results showed that the linearity of the method was suitable in the range of 0.232~2.318 μg/mL,R2=0.9971,the injection volume was 10 μL,the limit of quantitative of the instrument was 0.0774 μg/mL. The sensitivity was enough to meet the needs of folic acid detection in sports nutrition food,the recovery of the method was between 96.98% and 100.50%,and the standard and sample solutions were stable in 8 h. This newly developed method could not only solve the problems of extraction,purification,but also have advantages of convenience,accuracy,wide linear range,high sensitivity. Never the less,it was reproducible,specific,and robust with high recovery rate,which could meet the needs of the quantification of folic acid in sports nutrition foods.