煤中氯含量测定结果不确定度的评定

对用GB／T3558-1996《煤中氯的测定方法》中高温燃烧水解-电位滴定法测定煤中氯含量测定结果的不确定度进行了评定。通过对影响测定结果的不确定度分量的分析和量化,求得煤中氯含量测定结果的扩展不确定度为0．003％。     

顶空气相色谱法测定医用透明质酸钠凝胶中乙醇残留量的不确定度

按YY 0308-2004要求,采用顶空气相色谱法测定了医用透明质酸钠凝胶中的乙醇残留量,依据JJF l059-1999,CNAS-GL 06,对测量结果的不确定度来源进行了系统分析,并对各不确定度分量进行了评定和量化,计算了合成标准不确定度和扩展不确定度,测定结果为(344.10±37.51)μg/g,k=2。结果表明,影响测量结果的主要因素为标准曲线拟合引入的不确定度。     

石墨炉原子吸收光谱测定加热不燃烧烟烟草材料中铅含量的不确定度评定

为评价石墨炉原子吸收光谱法(GF-AAS)测定加热不燃烧烟(HNB)烟草材料中铅含量检测方法的可靠性和检测结果的准确性,采用自下而上法(bottom-up)评定铅含量检测结果的不确定度,分析了测量不确定度的来源及各不确定度分量的影响程度.结果表明,加热不燃烧烟烟草材料中铅含量为2.02 mg/kg,扩展不确定度为0.26 mg/kg(k=2).测量不确定度主要来源于标准曲线拟合和仪器稳定性.故选择适宜的试验方案及试剂,设置合适的仪器参数,确保良好的仪器状态及性能,是获得准确检测结果的前提条件.     

芥子气纯度测定不确定度分析与评定

采用酸碱滴定法测定芥子气纯度,对测量结果的不确定度进行评定。分析了测定过程中不确定度来源,包括滴定剂的标定、消耗滴定剂体积、样品称量等引入的不确定度及其计算方法,最后合成得到标准不确定度。当芥子气纯度测定结果为94.78%时,扩展不确定度为0.34%(k=2)。实验结果表明,样品称量引入的不确定度对测量结果的影响最大。     

分光光度法测定空气中甲醛不确定度评定

采用分光光度法测定空气中甲醛,对测定结果的不确定度进行评定。采用酚试剂分光光度法测定空气中甲醛,分析测定过程中的各项不确定度来源,包括样品采集、标准工作溶液配制、标准工作曲线拟合、测定仪器以及重复测定等引入的不确定度,计算合成不确定度,最后获得相对扩展不确定度。当空气中甲醛质量浓度为0.0244~0.2218 mg/m^3时,测定结果在95%置信区间时的相对扩展不确定度为0.1172(k=2)。不确定度主要来源于A类不确定度和系列标准工作溶液制备、标准工作曲线拟合、水中甲醛溶液标准物质的稀释引入的不确定度。     

气相色谱法测定果汁饮料中甜蜜素含量的不确定度评定

采用气相色谱法测定果汁饮料中甜蜜素的含量,对测定结果的不确定度进行了分析,对各不确定度分量进行了评定和量化,计算了合成标准不确定度和扩展不确定度。不确定度主要来自量器校准和标准曲线引入的不确定度。果汁饮料中甜蜜素的含量结果表示为（0．350±0．023）g／kg,k=2。     

超高效液相色谱法测定化妆品中孕激素的不确定度

采用分层建模方法建立了超高效液相色谱法测定化妆品中黄体酮结果不确定度评定的数学模型,对测量过程中的不确定度来源进行逐层分析和合成,运用最小二乘法对外标曲线拟合的不确定度进行了评定.超高效液相色谱法测定化妆品中孕激素含量的相对合成标准不确定度为0.022,相对扩展不确定度为0.044.该评定对采用外标法定量的高效液相色谱、气相色谱等测定结果的不确定度评定具有参考作用.     

纺织品中五氯苯酚残留量测量不确定度评定

采用气相色谱法测定纺织品中残留的五氯苯酚含量,对整个测量过程的不确定度来源进行了分析,并对不确定度各个分量进行了评定与合成。当五氯苯酚测定结果为0.570mg/kg时,扩展不确定度为0.054mg/kg,并给出了检测结果不确定度表达式。     

离子色谱法测定地下水中硝酸盐氮含量的不确定度评定

采用不确定度连续传递模式,讨论了不同回归方式对离子色谱法测定岩溶地下水中硝酸根分析结果不确定度评定的差异.结果表明：（1）测定结果的不确定度主要来源于标准溶液配制过程引入的不确定度、校准曲线拟合及回归过程产生的不确定度和仪器测定过程引入的不确定度三部分;（2）不同校准曲线回归方式对测定结果的不确定度评定在不同测量水平上有不同的影响,当地下水中硝酸根含量越低,差异越大.此外,对不确定度评定过程中的各个分量进行量化,通过合成得到硝酸根测定结果的不确定度评定模型.     

粘油类产品中钠快速测定方法测量不确定度的评定

对粘油类产品中钠的快速测定方法的不确定度进行了评定,并建立了数学模型,对各不确定度分量进行了分析和量化。测量结果的扩展不确定度为0.40mg/kg。     

Bump-hunting for the proficiency tester--searching for multimodality

Kernel density estimation is a method for producing a smooth density approximation to a dataset and avoiding some of the problems associated with histograms. If it is used with a degree of smoothing determined by a fitness for purpose criterion, it can be applied to proficiency test data in order to test for multimodality in the z-scores. The bootstrap is an essential additional technique to determine how rugged the initially estimated kernel density is: the random resampling of the data in the bootstrap simulates a complete blind repeat of the proficiency test. In addition, useful estimates of the standard error of a mode can be thus obtained. It is suggested that a mode and its standard error can be used as an assigned value and its standard uncertainty.     

溶剂化的热力学集团展开理论

把二元溶液的过剩内能（excess energy）分成溶剂-溶剂、溶剂-溶质及溶质-溶质相互作用部分。利用集团展开方法给出了二元溶液在正则系综的配分函数的表达式,利用该表达式得到了溶质的偏摩尔内能(partial molar energy)和偏摩尔熵(partial molar entropy)的表达式。在无限稀溶液情形,过剩偏摩尔内能的溶剂-溶剂部分又称重组织内能（reorganization energy）,它反映了溶质存在时对其周围溶剂分子之间的相互作用能的影响。研究表明,在溶质的粒子数密度相对较大时,溶质分子之间的相互作用将影响过剩偏摩尔内能的溶剂-溶剂部分,对于稀溶液,过剩偏摩尔内能的溶剂-溶剂部分与溶质的摩尔分数成线性关系。对低密度二元溶液,溶质的过剩偏摩尔内能和过剩偏摩尔熵也与溶质的摩尔分数成线性关系。     

Call for nominations for the Heinrich-Emanuel-Merck Award

News and Announcements

Call for nominations for the Heinrich-Emanuel-Merck Award     

A methodology for choosing parameters for ESR readout of alanine dosimeters for radiotherapy

Spectrometer settings for ESR readout of alanine dosimeters for radiotherapy have been investigated. Several ESR parameters were studied and determined. The main reason for this work is to choose the suitable parameters to increase signal-to-noise ratio and to reduce the uncertainty on ESR readout, which is one of the main components of uncertainty of alanine/ESR dosimetry system for radiotherapy. The new spectrometer settings have been applied for ESR readout of alanine dosimeters irradiated from 1 to 10 Gy. A higher signal-to-noise ratio has been achieved compared to our old spectrometer settings. The extended uncertainty (k=2) has been evaluated in the dose range 2–10 Gy (maximum uncertainty of 4.9% for 2 Gy, while minimum uncertainty of 1.4% for 10 Gy), which implies that the alanine/ESR dosimetry system can be applied to radiotherapy dose level that needs a global accuracy of 5%.     

Protecting Groups for Thiols Suitable for Suzuki Conditions

The thiol group is one of the few groups NOT tolerated by the Suzuki reaction. Therefore, a new protective group, the 2-methoxyisobutyryl group, was developed by tuning the electronic/steric properties of the acyl residue. Other thioesters, such as thioacetate, result in a more or less dominant side reaction, which to date has not been described: sulfur-assisted acylation of boronic acids. The reaction pathway for this new reaction is discussed.     

Polymeric Lids for Microcontainers for Oral Protein Delivery

Oral delivery of proteins and peptides is one of the main challenges in pharmaceutical drug development. Microdevices have the possibility to protect the therapeutics until release is desired, avoiding losses by degradation. One type of microdevice is polymeric microcontainers. In this study, lysozyme is chosen as model protein and loaded into microcontainers with the permeation enhancer sodium decanoate (C10). The loaded microcontainers are sealed and functionalized by applying polymeric lids onto the cavity of the devices. The first lid is poly(lactic‐co‐glycolic) acid (PLGA) and on top of this either polyethylene glycol (PEG) or chitosan is applied (PLGA+PEG or PLGA+chitosan, respectively). The functionalization is evaluated in vitro for morphology, drug release, and mucoadhesive properties. These are coupled with in vitro and ex vivo studies using Caco‐2 cells, Caco‐2/HT29‐MTX‐E12 co‐cultures, and porcine intestinal tissue. PLGA+chitosan shows slower release compared to PLGA+PEG or only PLGA in buffer and the transport of lysozyme across cell cultures is not enhanced compared to the bulk powder. Microcontainers coated with chitosan or PEG demonstrate a three times stronger adhesion during ex vivo mucoadhesion studies compared to samples without coatings. Altogether, functionalized microcontainers with mucoadhesive properties and tunable release for oral protein delivery are developed and characterized.