Abstract: A method for the determination of lactose in low-lactose milk and lactose-free milk by using ion chromatography was developed. Lactose from samples was extracted with 3% acetic acid as a protein precipitator. The method was performed on a CarboPacTM PA20 column by gradient elution. The analyte was detected with an electrochemical detector and quantified by an external standard method. The limit of quantification was 100 mg/kg and the limit of detection was 50 mg/kg for lactose in milk. The recoveries at spiked concentration levels of 100–500 mg/kg were 92.3%–103.4%, with relative standard deviations between 1.44% and 4.43%. This method proved to be rapid, accurate, repeatable, sensitive and simple.

Key words: low-lactose milk; lactose-free milk; ion chromatography; lactose

摘要： 建立低乳糖和无乳糖牛乳中乳糖含量的离子色谱测定法。用3%冰乙酸作为牛乳蛋白沉淀剂，CarboPacTM PA20 分析柱分离乳糖，采用梯度洗脱程序进行洗脱，电化学检测器检测，外标法定量。结果表明：乳糖的检出限为 50 mg/kg，定量限为100 mg/kg；当牛乳中乳糖添加量为100～500 mg/kg时，回收率为92.3%～103.4%，相对标准偏 差为1.44%～4.43%。该方法具有快速、准确、重复性好、灵敏度高及操作简便的特点。

关键词: 低乳糖牛乳；无乳糖牛乳；离子色谱法；乳糖