钡-硫酸钡重量基准方法研究

为将钡-硫酸钡重量法发展成为可行的基准方法,选定浓度为20mg/g的钡溶液为研究对象,采用重量法与仪器分析相结合,测定溶液中钡含量和各不确定度影响因素的量值,并对测定结果进行了讨论.结果表明重量法与仪器分析相结合,明显改善了测量重复性,提高了测量不确定度,得到扩展不确定度为0.08%（k=2）.     

钡溶液标准物质的研制

选择氯化钡为原料,经纯度分析后,配制成目标浓度为20 mg/mL的钡溶液标准物质.采用BaSO4重量基准法与仪器分析相结合的方法进行均匀性检验、稳定性监测与定值.对影响测量结果的因素进行了系统研究,将各影响量降至最低水平,利用仪器分析法准确测定各影响因素的量值,并逐一进行修正;全面进行了测量不确定度评定.研制的钡溶液标准物质不确定度为0.08%(k=2),稳定性达1年.     

一种糖溶液旋光度的测量方法和不确定度分析

文章讨论了用普通的旋光仪测量糖溶液的旋光度时产生的测量不确定度较大,提出通过改变入射光和接收系统,即采用半导体激光和OCD接收与示波器显示相结合来测定旋光度,这样不仅能提高综合使用仪器的能力,同时提高了测量的精度.     

冷冻饮品中总固形物测定的不确定度分析

目的对重量法测定冷冻饮品中总固形物含量的不确定度进行分析,找出影响不确定度的因素,对不确定度进行评估,给出不确定度报告。方法依据商业部标准SB/T10009-1999、测量不确定度评定理论和方法建立数学模型,分析影响重量法测定冷冻饮品中总固形物结果的因素和来源,计算不确定度。结论根据电子分析天平对样品重量的测定数据和已给出相关数据建立数学模型,进行不确定度评定,方法直观简明,能如实反映重量法测量结果的置信度和准确度。     

火焰原子吸收分光光度法测定低合金钢中镍含量的不确定度评价

依据GB/T 223.54—1987利用火焰原子吸收分光光度法对低合金钢中镍进行了测定,对测定过程中不确定度的来源进行了分析,并对测定过程中的不确定度分量进行了合理评定,评定了测量结果的不确定度。找出了影响检测的主要因素,测量不确定度主要来源于试样称量、试样溶液定容和试样溶液质量浓度测定三方面,试样溶液质量浓度上机测定引入的不确定度主要来源于校准溶液配制、校准曲线拟合及重复性测定等,通过分析,明确了提高测量准确度的方法,给出了评定方法、步骤及结果。     

磷溶液标准物质的研制

介绍了磷溶液标准物质的研制。选择磷酸二氢钾为原料,经提纯后,配制成质量浓度为1000μg/mL的磷溶液标准物质。采用准确、可靠并能溯源的磷钼酸喹啉重量法进行定值、均匀性检验及稳定性检验。对影响测量不确定度的因素进行了分析,全面评定了标准物质的不确定度。研制的磷溶液标准物质,均匀性良好,扩展不确定度为0．5％（k=2）,稳定性达2年。     

气体吸附BET法测量固态物质比表面积不确定度评定

气体吸附BET法是测定固态物质比表面积最常用的方法之一。本文以使用商用仪器ASAP2020型比表面积分析仪测定标准物质NIST1899的比表面积为例,分析了测量不确定度的主要来源,并在对各不确定度分量进行了分别评定的基础上给出了扩展不确定度。     

连续流动微流法测定烟草中总氮的不确定度

为提高连续流动微流模块分析仪烟草总氮的检测结果准确性,依据JJF 1059.1-2012《测量不确定度评定与表示》,对连续流动微流法测定烟草中总氮的测量不确定度进行了评定。采用因果关系图系统分析影响不确定度的各因素,在此基础上构建了微流法测量不确定度的评定方案,并通过测量模型评定了各不确定度分量。结果表明:(1)总氮的测定值为1.56%,在95%包含概率下其扩展不确定度分别为0.05%;(2)影响测量不确定度的因素主要有标准溶液配制、测量重复性、最小二乘法校准曲线拟合;(3)采用称量法配制标准溶液、选择合适的标准工作溶液浓度范围,可进一步提高分析的精准度。     

重量法测定电镀锌圆钢片“镀锌层重量不确定度”的评定

实验室能力验证中其中有“镀锌钢板镀锌层的测定”一项,要求报出扩展不确定度,笔者通过重量法测定电镀锌圆钢片的镀锌层重量进行了不确定度的评定,分析了该方法测定过程的不确定度来源,建立了测量模型并计算了各标准不确定度分量、合成标准不确定度、扩展不确定度等。     

环境监测用6种金属离子混合溶液标准物质的研制

详细介绍水中锰、铜、钡、锌、镍、铬6种重金属离子溶液标准物质的研制。采用经准确校准后的仪器设备,主要包括电感耦合等离子体光谱仪和质谱仪、离子色谱仪等对6种金属原料的杂质进行分析,同时对原料间相互包含的干扰杂质分析测定,最后结合质量平衡法对6种原料进行纯度定值。根据F检验和t检验结果表明,采用重量-容量法制备的水中锰、铜、钡、锌、镍、铬离子混合溶液标准物质具有良好的均匀性和稳定性,定值结果为100μg/mL,相对扩展不确定度为U=2%(k=2)。该标准物质可用于分析仪器的检定校准,环境等领域中多元素分析方法确认与质量控制。     

铑电镀液中铑含量不同测定方法的比较

铑作为一种贵金属,准确测定其在镀液中的含量非常重要.通过对铑的标准浓度溶液进行重量法、等离子体发射光谱法(ICP)、火焰原子吸收光谱法(FAAS)和改进后的FAAS(引入一个校正因子, 对FAAS测定方法进行了优化、校正)等不同方法的测定,比较了不同测定方法的适用范围和精确度.结果表明:对于杂质少的铑电镀液,宜采用重量法测定,其测定偏差在4%以内,硼氢化钠作为还原剂的重量法的测定偏差可控制在0.2%以内;对于杂质多的铑电镀液,用ICP,改进后的FAAS均能获得满意结果,相对偏差都小于1% .     

Delta34S measurements of sulfur by multicollector inductively coupled plasma mass spectrometry

An accurate and precise method for the determination of delta34S measurements by multicollector inductively coupled plasma mass spectrometry has been developed. Full uncertainty budgets, taking into consideration all the uncertainties of the measurement process, have been calculated. The technique was evaluated by comparing measured values with a range of isotopically enriched sulfur solutions prepared by gravimetric addition of a 34S spike. The gravimetric and measured results exhibited a correlation of R2 >0.999. Repeat measurements were also made after adding Na (up to 420 microg g(-1)) and Ca (up to 400 microg g(-1)) salts to the sulfur standard. No significant deviations in the delta34S values were observed. The Russell correction expression (Ingle, C.; Sharp, B.; Horstwood, M.; Parrish, R.; Lewis, D. J. J. Anal. At. Spectrom. 2003, 18, 219) was used to correct for mass bias on the 34S/32S isotope amount ratio from the mass bias observed for the 30Si/28Si isotope amount ratio. Consistent compensation for instrumental mass bias was achieved. Resolution of the measured delta34S values was better than 1 per thousand after consideration of all uncertainty components. The technique was evaluated for practical applications by measurement of delta34S for a range of mineral waters by pneumatic nebulization sample introduction and the analysis of genuine and counterfeit pharmaceuticals using both laser ablation sample introduction and liquid chromatography. For the former two cases polyatomic interferences were resolved by operating the MC-ICPMS in medium resolution, while for the chromatographic analyses polyatomic interferences were minimized by the use of a membrane desolvator, allowing the instrument to be operated at a resolution of 400.     

电气设备中保护气体监测用SO2F2气体标准物质研制

介绍了钢瓶装氦气中氟化硫酰（SO₂F₂）气体标准物质的研制过程。标准混合气是通过将SO₂F₂和氦气充装到钢瓶中制备而成,研究了气瓶内压力和保存时间对混合气稳定性的影响。对混合气配制的一致性进行了考察,并对引入的不确定度进行了评估,由结果可以看出,每个摩尔分数点混合气的量值一致性均较好。通过对称量法配气与稳定性导致的不确定度的评价,结果显示利用称量法制备的氦气中SO₂F₂气体标准物质在6个月内的稳定性良好,其相对扩展不确定度不大于2%。     

Synthesis and sintering of barium titanate fine powders by ultrasonic spray pyrolysis

Crystalline, spherical barium titanate fine powders with a narrow particle size distribution were prepared by ultrasonic spray pyrolysis. The stability of the starting solution was influenced by type of barium source and peptizer. The particle structure was influenced by the pyrolysis temperature of the barium source. The particle structure derived from barium acetate was dense, while powders derived from barium nitrate involved a lot of hollow particles. As-prepared powders were crystallized to a perovskite structure. Inductively coupled plasma analysis showed that the BaO/TiO₂ molar ratio of as-prepared powders was 50.5:49.5. The effects of the concentration of the starting fluid, pyrolysis temperature and flow rate of carrier air through the furnace on powder characteristics such as particle size, size distribution and crystal phase were investigated. The particle size depended on the concentration of starting solution and the flow rate of carrier air, but the particle size distribution was independent of these variables. Single-phase BaTiO₃ was obtained at more than 700°C. The relative density of barium titanate sintered at 1200°C was 98%. The hollow particles in the powders resulted in a low sintering density and a large grain size. The dielectric constant and tan δ of barium titanate at 25°C were 4500 and 0.02, respectively.     

Methods for the Determination of the Carbon Dioxide Evolved from Effervescent Systems

Different methods for determining the carbon dioxide evolved from effervescent systems are described. In addition, a comparison between some of them is carried out when a stoechiometric mixture of L-tartaric acid and sodium bicarbonate reacts.

The methods compared are: gravimetric, volumetric and gasometric.

The gravimetric methods can be direct or indirect. The direct ones are based on taking in the carbon dioxide by a sorbent substance. The increase of weight after the absorption represents the CO₂ evolved. In the indirect gravimetric methods the amount of carbon dioxide is determined by substraction of the weight of the sample after and before the effervescent reaction.

The volumetric methods are based on an acid-base titration. In the method used, the carbon dioxide released reacts with barium hydroxide. The excess of barium hydroxide is titrated with oxalic acid. It is possible to calculate then the carbon dioxide produced in the reaction from the volume of oxalic acid used.

In the gasometric methods the volume of gas is directly determined by the displacement of a solution when the gas is released.

The gasometric method seems to be the most efficient among the studied ones.     

ICP-AES法测定原油中镍含量及不确定度评定

采用电感耦合等离子体发射光谱法(ICP-AES)定量分析原油中金属镍元素的含量,建立了测定镍含量不确定度的分析方法.从4个方面评定了不确定度分量的贡献,分别计算其相对标准不确定度,最终得到合成标准不确定度和扩展不确定度.通过分析计算表明,当原油中镍元素含量为19.64 mg/kg时,其扩展不确定度为0.20mg/kg(...     

关于容量法对铅矿氧化钡的测定分析

矿石中的氧化钡测定分析通常会采用硫酸钡重量法、铬酸铅容量法和EDTA容量法测定,对于含铅的矿物,铬酸铅容量法不适用。本文拟定了铅锌矿、铁矿、重晶石和岩石中1％以上的氧化钡的EDTA容量滴定方法,快速、准确、滴定终点突跃明显,以刚玉坩埚代替铂坩埚熔样,更易推广。     

液相色谱串联质谱法测定鸡蛋中利巴韦林及其代谢物总残留的不确定度评定

为提高鸡蛋食品安全检测结果准确性,建立了一种液相色谱串联质谱法(liquid chromatography-tandem mass spectrometry, LC-MS/MS)测定鸡蛋中的利巴韦林及其代谢物总残留量的不确定度数学模型。依据SN/T 4519-2016《出口动物源食品中利巴韦林残留量的测定》中的方法,对整个检测过程进行了不确定度评定。不确定度分量主要来源有测量的重复性、回收率、样品的称量、样品前处理稀释和定容、标准溶液配制、标准曲线拟合及仪器测定引入。经评定鸡蛋中利巴韦林及其代谢物总残留量结果为X=(9.94±0.88)μg/kg, k=2; 其中标准曲线拟合过程中引入的不确定度分量影响最大。     

化肥标准物质中钾含量准确定值方法研究

采用四苯硼酸钾重量法与离子色谱相结合法对化肥标准物质硫酸钾中的钾含量进行了定值。使用离子色谱仪对重量法测量过程中的沉淀残留、滤液中钾含量及四苯硼酸钾沉淀物包夹钠含量进行了测定,同时对四苯硼酸钾重量法各个环节的称量浮力修正、样品的不溶物、沉淀残留、滤液和包夹等影响进行了系统分析。并对重量法测定结果进行了修正,将各影响量降到了最低水平。用该方法对硫酸钾标准物质进行了复制和准确定值,其中钾含量为44.69%,扩展不确定度为0.17%(k=2),均匀性和稳定性均符合要求,保证了量值溯源的可靠性。     

甲醇中8组分苯系物溶液标准物质的研制

介绍甲醇中8组分苯系物溶液标准物质的研制过程。采用气相色谱仪(GC-FID)、电感耦合等离子体质谱仪(ICP-MS)和卡尔·费休水分仪(KF)等检测方法,结合质量平衡法对原料纯度进行验证,其纯度验证结果与证书标示值一致,并在不确定度范围内。经F检验和t检验,结果表明,采用重量-容量法制备的甲醇中8组分苯系物溶液标准物质具有良好的均匀性和稳定性,其定值结果为1000μg/mL,相对扩展不确定度为3%(k=2)。该溶液标准物质可用于环境分析中苯系物含量的测定和量值溯源。