摘要
建立了在线透析-流动注射光度法测定奶及奶制品中尿素的方法。加入三氯乙酸使样品中蛋白质沉淀,离心过滤去除沉淀的蛋白质,在线透析去除剩余的脂肪及大分子,避免干扰光度分析。在Fe3+存在时,尿素与二乙酰一肟在酸性溶液中水解生成的二乙酰反应生成红色化合物,在534 nm处测量吸光度,加入硫代氨基脲提高显色强度。实验对试剂的浓度、在线透析模块的结构、混合环的长度均进行了优化。在最佳的分析条件下,尿素浓度在0～500 mg/kg的范围内,可获得良好的线性(r≥0.999)。方法的检出限为1.3 mg/kg;相对标准偏差为0.91%～1.95%;样品测定频率分别为22样/h;牛奶及奶制品的加标回收率为94.1%～109.8%。
An in-line dialysis flow-injection-spectrophotometric method was developed to determine urea in milk and milk products.Protein was precipitated from a sample portion by the addition of trichloroacetic acid solution.The precipitated milk protein was removed by centrifuging and filtration.Remaining protein and fat which could interfere with the subsequent analysis was removed by in-line dialysis.The spectrophotometric method was based on the reaction of urea with diacetyl which was produced from diacetylmonoxime hydrolysis in acid solution when the Fe^3＋ co-existed in solution.The red compound obtained from the said reaction was measured at 534 nm.To enhance the intensity of the color,aminothiourea was added.Experimental parameters,including the reagent concentration,on-line dialysis unit structure,the length of the mixing coil,were optimized.Under optimized conditions,the linear calibration curves were obtained for the concentration range of 0-500.0 mg/kg（r≥0.999）.The proposed method had low detection limit of 1.3 mg/kg urea.The relative standard deviation was 0.9%-2.0% with the sample throughput of 22 samples/h.The urea was determined various milk products with the standard addition recovery of 94.1%-109.8%.The method was simple,rapid and has been used to determine the urea in milk and milk products with satisfactory results.
出处
《分析化学》
SCIE
EI
CAS
CSCD
北大核心
2011年第2期183-187,共5页
Chinese Journal of Analytical Chemistry
基金
科技部"十五"科技攻关项目(No.2004BA210A05)资助
