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    柱切换-液相色谱法测定婴儿配方奶粉中4种雌激素

    LC Determination of 4 Estrogens in Infant Formula with Column Switching

    • 摘要: 婴儿配方奶粉样品用水超声溶解后,用乙腈超声提取30 min,以15 000 r·min-1转速在5℃下离心10 min,残渣用乙酸乙酯提取,合并两次提取液。上层有机相于40℃下用氮气吹至近干,加入50%(体积分数)甲醇溶液溶解,溶解液过0.22 μm滤膜,采用柱切换-液相色谱法测定滤液中4种雌激素的含量。以Thermo BioBasic SEC-120色谱柱为净化柱,Waters XBridge BEH C18色谱柱为分析柱,用水和甲醇以不同比例混合的溶液为流动相进行梯度洗脱,用紫外检测器测定。4种雌激素的质量浓度均在1.0~20 μg·L-1内与其对应的峰面积呈线性关系,测定下限(10S/N)为0.1~0.3 μg·kg-1。以空白样品为基体进行加标回收试验,所得回收率为90.0%~105%,测定值的日内相对标准偏差(n=6)为1.6%~5.4%,日间相对标准偏差(n=11)为3.5%~6.2%。

       

      Abstract: After ultrasonic dissolution with water, the sample of infant formula was extracted ultrasonically for 30 min with acetonitrile. At the speed of 15 000 r·min-1, the solution was centrifugated for 10 min at 5℃. The residue was extracted with ethyl acetate and then the two extracts were combined. The upper organic phase was evaporated to near dryness by N2 blowing at 40℃. The residue was dissolved with 50% ( φ) methanol solution. The solution was filtered on 0.22 μm filtering membrane. LC was applied to the determination of 4 estrogens in the filtrate with column switching. Thermo BioBasic SEC-120 chromatographic column and Waters XBridge BEH C18 chromatographic column were used as purification column and analytical column respectively with mixtures of water and methanol with different mixing ratios as mobile phase in the gradient elution, and UV detector was adopted in the determination. Linear relationships between values of peak area and mass concentration of the 4 estrogens were kept in the same range of 1.0-20 μg·L-1, with lower limits of determination (10S/N) in the range of 0.1-0.3 μg·kg-1. On the base of blank sample, test for recovery was made by standard addition method; values of recovery found were in the range of 90.0%-105%, with intra-day RSDs (n=6) and inter-day RSDs (n=11) of determined values in the ranges of 1.6%-5.4% and 3.5%-6.2% respectively.

       

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