脱脂乳粉中硝酸盐、亚硝酸盐标准物质制备技术研究与评估  

Research on Preparation and Characterization of Nitrate and Nitrite Reference Material in Skim Milk Powder

作　　者：李筱翠[1] 卢晓华[2] 扈蓉[3] 阚莹[2] 郭敬[2] 史乃捷[2] 

机构地区：[1]北京化工大学理学院,北京100029 [2]中国计量科学研究院,北京100013 [3]深圳市计量质量检测研究院,广东深圳518055

出　　处：《分析测试学报》2015年第6期749-754,共6页Journal of Instrumental Analysis

基　　金：公益性行业科研专项经费资助(201204001)

摘　　要：对脱脂乳粉中硝酸盐、亚硝酸盐标准物质样品制备技术进行了研究与评估。采用基体添加-真空冷冻干燥法制备标准物质候选物。选择乙酸沉淀蛋白-固相萃取/离子色谱紫外检测法对所制备样品进行评估。与国家标准中推荐的离子色谱电导检测器相比,采用紫外检测器可有效避免乳粉基质中存在的共洗脱组分对亚硝酸盐测定的干扰,且测量精密度得到改善,更有利于满足样品制备回收率、均匀性与稳定性评估的技术要求。经考察,样品中亚硝酸盐、硝酸盐目标制备值与测得值吻合,制备回收率分别为91%,101%;经方差分析,最小取样量1.0 g时,由样品中亚硝酸盐与硝酸盐均匀性引入的相对不确定度分别为2.9%和0.3%;-70,-20,4,20,35,45℃下同步、加速稳定性实验与线性回归趋势分析结果表明,样品短期稳定性及-20℃干燥、真空、避光保存条件下的长期稳定性预期良好。本研究确立了乳粉中亚硝酸盐与硝酸盐标准物质研究的可行性,所建立的制备技术可以确保标准物质定值结果的准确性。The sample preparation technique for nitrate and nitrite reference material in skim milk powder was studied and evaluated. A candidate reference material was prepared by matrix spiking and vacuum freeze drying method. The method of acetic acid protein precipitation- solid extraction /ion chromatography with ultra violet detector was used for the assessment of the prepared sample.Compared with the conductivity detector suggested by the national standard method, UV detector could be more efficient in avoiding the co-eluted constituent interference in milk matrix and enhancing detection precision,to meet the requirement for evaluation of preparation recovery,homogeneity and stability of the milk powder sample. The measured values of nitrite and nitrate in sample agreed with the target values of preparation,with recoveries of 91% and 101%,respectively. The assessed relative uncertainties obtained from the in-homogeneity of nitrite and nitrate by analysis of variance were2. 9% and 0. 3%, respectively, with the minimum sample intake of 1. 0 g. The short-term and long-term stabilities in- 20 ℃,dry,vacuum and light-proof packaging conditions were predicted to be satisfactory by isochronous and accelerated stability study at- 70,- 20,4,20,35,45 ℃,and linear regression trend analysis. The research demonstrated that it was feasible to develop the milk powder reference material containing nitrate and nitrite. The established sample preparationmethod could ensure the accuracy of reference material＇s characterization results.

关 键 词：标准物质 离子色谱 硝酸盐 亚硝酸盐 乳粉 

分 类 号：O657[理学—分析化学] P578.5[理学—化学]