聚乙二醇法测定超滤膜截留率的不确定度评定

摘要

Molecular weight cut off and retention are two technical parameters of ultrafiltration membrane performance.Choosing PEG-20000 as a standard substance,establishing evaluation mathematical model of uncertainty of retention test results to analyze the sources of uncertainty,the retention test results were evaluated.The results indicates that the polydispersity coefficient(Mw/Mn)of PEG-20000 is 1.005,which is better than the standard test for molecular weight cut-off standard material distribution coefficient less than the requirements of 1.8 and GPC spectrum showed a single peak form,in line with PEG clear structure,molecular weight distribution narrow features,which fully meet the testing needs.There is a good linear relation between ABS and concentration in the standard curve and the correlation coefficient R2 is over 0.999.The retention ratio of the ultrafiltration membrane by PEG-20000 is 93.04％,through repeated experiment.The results were evaluated type A and type B uncertainty.It showed that expanded uncertainty is 2.90％ when coverage factor is k =2 and level of confidence is 95％.%截留率和切割分子量是表征超滤膜截留性能的主要技术参数.以聚乙二醇-20000为标准物质,建立截留率测试结果的不确定度评定数学模型,分析不确定度来源,评定超滤膜截留率测试结果的不确定度.结果表明,PEG-20000的多分散系数(Mw／Mn)为1.005,优于标准中对截留测试标准物质的分子量分布系数小于1.8的要求,GPC谱图呈现单峰形式,符合PEG结构明确、分子量分布窄的特点,完全满足测试需要,标准测试曲线线性好、相关系数R2大于0.999;通过重复性实验,测定了超滤膜对PEG-20000的截留率为93.04％,对该结果进行了A类和B类不确定度评定,当包含因子k=2、置信水平为95％时,扩展不确定度为2.90％.