红外分光光度法测定污泥中矿物油的不确定度评定

分析探讨了红外红外分光光度法测定污泥中矿物油含量不确定度的影响因素,并对其不确定度分量进行了评定,计算得到相对标准不确定度urel(X)为0. 0187,污泥样品中矿物油含量的标准不确定度u(X)为1. 0450mg/L,扩展不确定度U为2. 0899mg/L(k=2),所测污泥样品中的矿物油的含量为X=55. 83±2. 0899mg/L(k=2)。扩展不确定度贡献较大的主要分量是样品重复测定和配置三波长校准溶液引入的标准不确定度分量。     

高效液相色谱法测定塑料杯中双酚A的不确定度评估

采用高效液相色谱法(HPLC)测量了塑料杯中双酚A的含量,对测量不确定度进行了评定.采用求相对标准不确定度的方法对各变量进行了分析和计算.结果表明,标准曲线校准、仪器峰面积测量、标准样品的浓度和重复性是测量过程中的主要不确定度来源,其中标准曲线校准对总不确定度的影响最大.当塑料杯中双酚A的测定结果为9.18 mg/kg时,其扩展不确定度为0.32 mg/kg.     

气相色谱法测定高分子食品接触材料中抗氧剂含量的不确定度评定

采用气相色谱/电子捕获检测器(GC/ECD)测定高分子食品接触材料中的抗氧剂含量,建立模型,分析、评定测定过程中标准溶液、样品制备、重复性、标准曲线拟合等引入的不确定度,计算扩展不确定度.结果显示,标准溶液配制及曲线拟合对高分子食品接触材料中抗氧剂含量测定的不确定度影响较大,高分子食品接触材料中抗氧剂含量范围为(0.795～1.638)mg/kg,扩展不确定度范围在(0.0121～0.0265)mg/kg之间(P=95％,k=2).     

液相色谱法测定葡萄酒中着色剂含量的不确定度分析

采用液相色谱法测定葡萄酒中着色剂的含量,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。葡萄酒中着色剂的含量结果表示为(C±U)mg/kg,k=2。     

原子吸收光谱法测定汽油中锰含量不确定度的评定

通过分析原子吸收法测定汽油中锰含量操作过程,对锰含量测定结果的不确定度进行了评定。不确定度主要来源于样品溶液浓度和重复性,样品溶液浓度影响中尤以标准曲线拟合对不确定度的贡献最大。当汽油锰含量为4.89mg/L时,其扩展不确定度为1.18mg/L(k=2)。     

UPLC-MS/MS法测定化妆品中丙烯酰胺的不确定度评定

采用超高效液相色谱-串联质谱法(UPLC-MS/MS)测定了化妆品中丙烯酰胺含量,并对其进行了不确定度评定。根据 JJF 1059.1-2012《测量不确定度评定与表示》 建立测定化妆品中丙烯酰胺含量的计量学数学模型,分析和量化各不确定度分量。采用该方法检测的化妆品中丙烯酰胺的合成不确定度为0.033mg/kg,扩展不确定度为0.066mg/kg。实验测定的化妆品中丙烯酰胺含量结果为(0.502±0.066)mg/kg(k=2,置信概率P=95%)。评定结果表明,实验的不确定度主要由标准溶液配制和标准曲线拟合引入。     

液相色谱测定戊醛中催化剂不确定度的评定

建立了高效液相色谱法(HPLC)测定戊醛中的催化剂含量不确定度评定的数学模型。通过对整个测定过程中各种不确定度因素的研究,分析和评定了不确定度的来源,确定了不确定度分量和合成不确定度。结果表明,当戊醛中的催化剂含量为848mg/kg时,其扩展不确定度为6mg/kg(取包含因子k=2,置信概率约为95%),其中标准物质的纯度、标准样品和样品测量重复性对测量不确定度的影响较大,实验室应对其采取措施,减低不确定度。     

液态奶中三聚氰胺含量的测量不确定度评定

依据国标GB/T 22388-2008规定,采用高效液相色谱法对液态奶中三聚氰胺的含量进行了检测。建立数学模型,分析确定检测液态奶中三聚氰胺含量的不确定度来源,并对测量过程中的不确定度分量进行逐层分析与合成,得到合成标准不确定度和扩展不确定度分别为0.054 mg/kg和0.11 mg/kg。计算结果显示由样品溶液测量重复性、标准溶液测量重复性、标准溶液配制过程引入的不确定度分量对合成标准不确定度贡献较大,是不确定度的主要来源;由样品称量、定容引入的不确定度相对来说较小。     

大米中镉含量的测量不确定度评定

分析了石墨炉原子吸收光谱法测定大米中镉含量不确定度的各分量,对其测量不确定度进行合理的评定,结果表明:大米样品中镉的含量为0.18 mg/kg时,其扩展不确定度为0.01 mg/kg(k=2),不确定度主要是最小二乘法拟合标准工作曲线求得样品浓度过程和测试过程随机效应引入的。     

钠单元素溶液标准物质的研制

正一、材料与方法1.材料(1)氯化钠采用中国计量科学研究院研制的氯化钠纯度标准物质配制钠单元素溶液标准物质。氯化钠纯度标准物质的编号为GBW06103c,以氯计氯化钠纯度为99.994%,扩展不确定度为0.008%(k=2)。运用ICPMS测定了氯化钠中61种杂质的含量。由表1可知,除Hg、Ba、Sr含量为1.0mg/kg、0.125mg/kg和0.009mg/kg,其他58种元素含量均低于检出     

高效液相色谱法测定绝缘油中糠醛含量的不确定度评定

绝缘油中的糠醛含量能够评估变压器绝缘纸的老化状况,并反映其绝缘性能.通过高效液相色谱法对绝缘油中糠醛含量进行定量分析,建立数学模型,确定测定结果的不确定度来源为糠醛标准物质、标准油液的配制、标准曲线的拟合、样品制备、回收率、测量重复性,并对测试结果进行不确定度评定.实验结果表明,绝缘油中糠醛样品浓度为1.05 mg/k...     

气相色谱法测定食品包装中残留1,1-二氯乙烷含量的不确定度评定

在气相色谱法测定食品包装中残留的1,1-二氯乙烷含量过程中,对可能引入的不确定度进行了评定,并分析量化了不确定度来源。结果显示:由标准溶液产生的不确定度分量最大,其次是用标准曲线求1,1-二氯乙烷含量,再次是测量重复性,这三项是该法测定结果不确定度的重要来源。当1,1-二氯乙烷测量结果为23.6mg/kg时,其扩展不确定度为2.1334mg/kg(k=2)。     

小麦粉中偶氮甲酰胺含量测量的不确定度评定

分析了高效液相色谱法测定小麦粉中偶氮甲酰胺含量不确定度的各分量,对其测量不确定度进行合理的评定,结果表明:小麦粉样品中偶氮甲酰胺的含量为43.1mg/kg时,其扩展不确定度为2.6 mg/kg(k=2),不确定度主要是最小二乘法拟合标准工作曲线求得样品浓度过程引入的。     

Species-specific isotope dilution-based calibration for trace element speciation and its combined uncertainty evaluation: determination of tributyltin in sediment by HPLC-ICPMS

A method is described for the determination of tributyltin (TBT) in NRCC sediment CRM PACS-2 by isotope dilution (ID) analysis using HPLC-ICPMS. Reverse spike ID analysis was performed to determine the accurate concentration of a 117Sn-enriched TBT spike using a well-characterized natural abundance TBT standard. The accuracy of the latter is critical for obtaining reliable results. A unique approach, using hydride generation GC/MS, was developed to quantify the inorganic Sn and dibutyltin impurities in the natural abundance TBT standard. The true natural abundance TBT standard concentration was obtained following correction for these impurities. The total Sn concentration in the natural abundance TBT standard was determined by ID analysis using an enriched inorganic 117Sn following closed vessel mixed-acid digestion. Calibration of the enriched inorganic 117Sn standard was achieved by reverse ID analysis against a natural abundance inorganic tin standard prepared from the high-purity metal. An overall uncertainty associated with the present method was estimated, to which the uncertainties arising from measurement of the natural abundance TBT concentration, from the measurement of the isotope ratio in the spiked sample and in the reverse ID calibration solutions, and from estimation of the extraction efficiency were the main contributors. A concentration of 1.018 +/- 0.054 mg kg(-1) (expanded uncertainty, k = 2) as tin was obtained for TBT in PACS-2 using the present method, in excellent agreement with the certified value of 0.98 +/- 0.13 mg kg(-1) (95% confidence interval). A TBT concentration of 0.97 +/- 0.11 mg kg(-1) (expanded uncertainty, k = 2) as tin in PACS-2 was determined using the standard additions technique. Much smaller expanded uncertainty was obtained with ID, clearly demonstrating its superiority in providing more accurate and precise results over the method of additions. A detection limit (3sigma) of 0.02 mg kg(-1) for TBT, based on a 0.5-g subsample, was obtained.     

气相色谱内标法测定塑料制品中乙苯和苯乙烯含量的不确定度评定

目的 对气相色谱内标法测定塑料制品中乙苯和苯乙烯含量进行不确定度评定，为塑料制品中乙苯、苯乙烯含量测定的准确性提供参考。方法 依据GB 31604.16—2016采用气相色谱内标法对塑料制品中乙苯和苯乙烯含量进行测定，根据相应的测量模型，分析不确定度主要影响因素的来源，并对各影响因素引入的相对标准不确定度进行评估。结果 测量塑料制品中乙苯、苯乙烯的扩展不确定度分别为(23.83±1.50)、(23.90±1.26)mg/kg(P=95%、k=2)。结论 结果表明，混标工作液配制、试样重复测量、气相色谱仪性能是影响乙苯和苯乙烯含量测量不确定度的主要因素，应选择精度高且量程合适的量具，加强气相色谱仪的期间核查，提高实验人员操作的熟练水平，进一步减小测量不确定度，使测量结果更为准确、可靠。     

气相色谱——质谱联用法测定纺织品中多氯联苯残留量的不确定度评定

本文依据GB/T20387-2006《纺织品—多氯联苯残留量的测定》方法,对纺织品中多氯联苯残留量的测量不确定度的来源进行分析。以2、4、5-三氯联苯为分析对象,对测试过程中引入的不确定度各个分量进行了评定与合成。当2、4、5—三氯联苯测定结果为0.506mg/kg时,扩展不确定度为0.036mg/kg,并给出了检测结果不确定度表达式。     

Determination of arsenobetaine in fish tissue by species specific isotope dilution LC-LTQ-Orbitrap-MS and standard addition LC-ICPMS

An accurate and precise method for the determination of arsenobetaine (AsB, (CH(3))(3)(+)AsCH(2)COO(-)) in fish samples using exact matching species specific isotope dilution (ID) liquid chromatography LTQ-Orbitrap mass spectrometry (LC-LTQ-Orbitrap-MS) and standard addition LC inductively coupled plasma mass spectrometry (LC-ICPMS) is described. Samples were extracted by sonication for 30 min with high purity deionized water. An in-house synthesized (13)C enriched AsB spike was used for species specific ID analysis whereas natural abundance AsB, synthesized and characterized by quantitative (1)H NMR (nuclear magnetic resonance spectroscopy), was used for reverse ID and standard addition LC-ICPMS. With the LTQ-Orbitrap-MS instrument in scan mode (m/z 170-190) and resolution set at 7500, the intensities of [M + H](+) ions at m/z of 179.0053 and 180.0087 were used to calculate the 179.0053/180.0087 ion ratio for quantification of AsB in fish tissues. To circumvent potential difficulty in mass bias correction, an exact matching approach was applied. A quantitatively prepared mixture of the natural abundance AsB standard and the enriched spike to give a ratio near one was used for mass bias correction. Concentrations of 9.65 ± 0.24 and 11.39 ± 0.39 mg kg(-1) (expanded uncertainty, k = 2) for AsB in two fish samples of fish1 and fish2, respectively, were obtained by ID LC-LTQ-Orbitrap-MS. These results are in good agreement with those obtained by standard addition LC-ICPMS, 9.56 ± 0.32 and 11.26 ± 0.44 mg kg(-1) (expanded uncertainty, k = 2), respectively. Fish CRM DORM-2 was used for method validation and measured results of 37.9 ± 1.8 and 38.7 ± 0.66 mg kg(-1) (expanded uncertainty, k = 2) for AsB obtained by standard addition LC-ICPMS and ID LC-LTQ-Orbitrap-MS, respectively, are in good agreement with the certified value of 39.0 ± 2.6 mg kg(-1) (expanded uncertainty, k = 2). Detection limits of 0.011 and 0.033 mg kg(-1) for AsB with LC-ICPMS and ID LC-LTQ-Orbitrap-MS, respectively, were obtained demonstrating that the technique is well suited to the determination AsB in fish samples. To the best of our knowledge, this is first application of species specific isotope dilution for the accurate and precise determination of AsB in biological tissues.