An analytical method to determine lactulose in ultra high temperature (UHT) sterilized milk by liquid chromatographic separation,evaporative light-scattering detection and external standard quantitation is described in this paper.After the protein was precipitated by adding hydrochloric acid,the separation was performed with satisfactory results on a NH2 column using 75％ acetonitrile in water as the mobile phase.The precision expressed as relative standard deviation (n =6) was 0.77％,and the average recovery was in the range of 98.7％-102.6％.This method was simpler and less time consuming with good repeatability than traditional enzymatic hydrolysis method.It can provide an alternative way of determining lactulose in UHT sterilized milk.%采用液相色谱法分离、蒸发光散射检测器检测,外标法定量测定超高温瞬时灭菌乳中乳果糖的含量.采用盐酸沉淀蛋白,氨基色谱柱分离,流动相为75％乙腈溶液.该方法能使乳果糖得到很好分离,精密度为0.77％(n=6),平均回收率为98.7％～102.6％.高效液相色谱-蒸发光散射检测法较酶法操作简便、省时、重复性好,可以根据实验需求选择使用.
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