卡尔·费休库仑法水分测量技术及其应用研究

运用卡尔·费休库仑法,对日本三菱公司的CA-06水分测定仪不能直接检测的固体、油品和气体中水分含量进行检测技术研究.组建了固体、油品及气体水分检测系统,试验验证检测结果准确、可信,使CA-06水分测定仪应用范围得以拓宽.将建立的检测技术应用到泡沫材料、气相白碳黑、桂树脂及高纯氢气中的水分含量检测,均获得了较好的检测结果.     

碘离子溶液标准物质的研制及不确定度评定

建立碘离子溶液标准物质的制备方法及不确定度评定模型。采用质量-容量法制备特性量值为10μg/m L的碘离子溶液标准物质,该标准物质以高纯碘化钾为原料,经IC、ICP和ICP-MS 3种方法分析检测扣除其杂质,并且通过干燥减重法扣除其水分含量,精确测定碘化钾的纯度。制备的碘离子溶液标准物质均匀性和稳定性良好,定值结果的相对扩展不确定度为U=2%(k=2),有效期限为12个月,与同类标准样品GSB 04-2834-2011进行比对分析,结果显示,在规定的不确定度范围内量值具有一致性。该碘离子溶液标准物质可用于环境水质、食品安全等领域的安全检测及相应分析方法的确认与评价。     

甲醇中微量六氯丁二烯溶液标准物质的研制及不确定度评定

建立甲醇中六氯丁二烯溶液标准物质的制备方法,并通过数学模型评定该标准物质的不确定度。以气相色谱仪(GC-FID/ECD)、电感耦合等离子体质谱仪(ICP-MS)和卡尔·费休水分仪(KF)为主要分析手段分别测得六氯丁二烯中主成分、无机杂质及水分含量,并通过质量平衡法确定准确纯度。采用重量-容量法制备10.0μg/m L的甲醇中六氯丁二烯溶液标准物质。均匀性和稳定性考察结果良好。通过与国外同种产品开展量值比对,证实该特性量值的一致性。研制的甲醇中六氯丁二烯溶液标准物质具有较小扩展相对不确定度(U=3%,k=2),使用有效期限为24个月。     

烘干法水分测定仪检定用氯化钠溶液标准物质

为满足烘干法水分测定仪检定和质量控制中的量值溯源,研制以氯化钠纯度标准物质为原料、质量浓度为5.00%的氯化钠溶液标准物质。该标准物质经检验证明其均匀性良好,在室温下可稳定保存12个月。其量值采用重量容量法确定,扩展不确定度为0.02%(k=2)。该标准物质经多家实验室采用多种原理的方法进行验证,证明其量值准确可靠,可作为量值传递的标准用于烘干法水分测定仪检定。     

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。     

高纯氦气中杂质标准物质的研制

介绍了重量法研制高纯氦气中微量氢气、氖气、氧气、氩气、氮气、甲烷、一氧化碳和二氧化碳8种杂质标准物质的过程,包括重量法制备技术、稀释气中相关杂质的定量及稳定性考察等。研制的8种微量气体标准物质的种类和摩尔分数参照国标GB/T 4844-2011中对高纯氦气的规定,摩尔分数范围在0.5~4.0μmol/mol之间,扩展不确定度为1%~3%（k=2）。通过参加CCQM相关国际关键比对,验证了标准物质量值的准确度。与现有的国家二级标准物质相比,研制的标准物质在种类和不确定度方面都已达到了较高水平。     

用标准物质校准泄漏检测装置现场校验系统

利用气相色谱仪,用六氟化硫气体标准物质对RA104E型气体泄漏检测装置现场校验系统进行校准,评定校准结果的不确定度,并作出六氟化硫物质的量分数范围为1~3mmol/mol的量值传递框图,讨论进一步减小校准结果不确定度的途径以及此校准方法应用于其他气体稀释装置的发展前景。     

黏度标准物质研制

为满足液体黏度测量仪器量值溯源、黏度测量质量控制对黏度标准物质的需求,研制具有不同黏度水平的系列黏度标准物质.以精制甲基硅油为原料,采用哈克旋转流变仪、标准毛细管黏度计和基准恒温槽测试该系列标准物质的流动性、黏度、黏度-温度变化率以及表面张力,并对其均匀性、稳定性和不确定度进行检验和评定.实验结果表明:该系列黏度标准物质均匀性和稳定性良好,在(20±5)℃下可保存一年,相对扩展不确定度为0.24％～0.61％(k=2).通过与国家一级黏度标准物质量值比对,其定值结果的准确性达到国家二级标准物质的技术指标要求.该系列标准物质可用于黏度测试过程中的方法验证和检测结果质量控制等.     

黏度标准物质研制

为满足液体黏度测量仪器量值溯源、黏度测量质量控制对黏度标准物质的需求,研制具有不同黏度水平的系列黏度标准物质。以精制甲基硅油为原料,采用哈克旋转流变仪、标准毛细管黏度计和基准恒温槽测试该系列标准物质的流动性、黏度、黏度-温度变化率以及表面张力,并对其均匀性、稳定性和不确定度进行检验和评定。实验结果表明:该系列黏度标准物质均匀性和稳定性良好,在(20±5)℃下可保存一年,相对扩展不确定度为0.24%~0.61%(k=2)。通过与国家一级黏度标准物质量值比对,其定值结果的准确性达到国家二级标准物质的技术指标要求。该系列标准物质可用于黏度测试过程中的方法验证和检测结果质量控制等。     

甲醇中氯苯溶液标准物质的制备技术研究及不确定度评定

建立甲醇中氯苯溶液标准物质的研制及不确定度评定方法。使用气相色谱(GC)和液相色谱(HPLC)两种不同方法精确测定氯苯主成分含量,电感耦合等离子体质谱仪(ICP-MS)和卡尔·费休水分仪(KF)测定无机杂质和水分含量,并最终通过质量平衡法对氯苯纯度进行准确定值。采用重量-容量法制备特性量值为10.0μg/m L的甲醇中氯苯溶液标准物质,其主要用于污染物中氯苯的成分分析、环境评价以及相应分析方法的确认等,制备的标准物质均匀性和稳定性良好,定值结果的相对扩展不确定度为U=3%(k=2),有效期限24个月,通过与同类国家标准样品甲醇中氯苯GSB 07-1220——2000量值比对,验证制备方法定值结果的准确性。     

Preparation of Honey Reference Material for Water Content by Karl Fisher and Refractometric Methods

Certified reference materials are essential tools for calibration of measuring instruments, validation of analytical methods and assuring quality of measurement results. However, in the case of water content in honey, which is used to determine the quality and the marketability of honey, there is a lack of matrix reference materials. Certified reference material for water content in honey has been developed by the National Institute of Standards, Egypt. This article describes production of the material from processing to value assignment. Characterization of the material was carried out by refractometric and Karl Fisher titration procedures, where homogeneity and stability studies were carried out by Karl Fisher titration method. The measurement results were statistically analysed and weighted mean was calculated as assigned value. The certified value and expanded uncertainty were found 16.24 ± 0.33 g/100 g, respectively.     

Certification of Three Reference Materials for α- and γ-Tocopherol in Edible Oils

Tocopherols are important vegetable oil constituents, and their reliable quantitative analysis depends largely on the existence and quality of certified reference materials (CRMs) which provides traceability of the measurement results to the SI units. Since there is a lack of suitable CRMs in case of tocopherols analysis, three matrix reference materials from corn, peanut and soybean oils were certified for the content of α and γ-tocopherols. Homogeneity and stability of the prepared reference materials were studied and certification was done by two independent chromatographic analytical methods. The measurement results were statistically treated and the certified values of α and γ-tocopherol in corn, peanut and soybean oils were assigned and their associated expanded uncertainties were estimated as: 322.04 ± 8.62, 771.48 ± 15.31, 106.23 ± 5.19, 108.94 ± 9.72, 140.66 ± 5.93, 418.00 ± 14.36 mg/kg, respectively. These values were found useful for many food testing laboratories in validation of analytical methods and analytical quality control.     

Development and evaluation of a reference measurement procedure for the determination of estradiol-17beta in human serum using isotope-dilution liquid chromatography-tandem mass spectrometry

Estradiol is the most potent natural estrogen and is derived from the ovaries. Its concentration in blood is measured to determine ovarian function. A reference measurement procedure for estradiol in serum involving isotope-dilution coupled with liquid chromatography-tandem mass spectrometry (LC/MS/MS) has been developed and critically evaluated. A deuterated estradiol (estradiol-d3) was used as an internal standard. The estradiol and its internal standard were extracted from serum matrix using solid-phase extractions and derivatized with dansyl chloride prior to reversed-phase LC/MS/MS. The accuracy of the measurement was evaluated by a comparison of results of this reference method on lyophilized human serum reference materials for estradiol [Certified Reference Materials (CRMs) 576, 577, and 578] with the certified values determined by gas chromatography/mass spectrometry (GC/MS) reference methods and by a recovery study for the added estradiol. The results of this method for estradiol agreed with the certified values within the uncertainty of the measurements for the three CRMs. The recovery of the added estradiol ranged from 100.7 to 101.8%. This method was applied to the determination of estradiol in frozen serum samples from three individual female donors. Excellent reproducibility was obtained with within-set coefficient of variations (CVs) ranging from 0.6 to 2.2% and between-set CVs ranging from 0.2 to 0.4%. Excellent linearity was also obtained, with correlation coefficients of all linear regression lines (measured intensity ratios vs mass ratios) ranging from 0.998 to 1.000. The detection limit at a signal-to-noise ratio of approximately 3 was 0.6 pg of estradiol (or 1 ng/L, as expressed as a concentration). This well-characterized LC/MS/MS method for serum estradiol, which demonstrates good accuracy and precision, low susceptibility to interferences, and comparability with GC/MS reference methods, qualifies as a reference measurement procedure that can be used to provide an accuracy base to which routine methods for estradiol can be compared and that will serve as a standard of higher order for measurement traceability.     

2,3,4-三氯苯甲醚标准物质研制与定值

研制了2,3,4-三氯苯甲醚标准物质,介绍了其制备与定值方法。将制备的2,3,4-三氯苯甲醚标准物质分装成500瓶样品,随机抽取其中11瓶做均匀性检验,经F检验和t检验,结果表明在95%置信范围内样品均匀性良好。按短期与长期稳定性分别进行稳定性检验,结果表明在常温20℃下,2,3,4-三氯苯甲醚的稳定期不少于12月。采用液相色谱法和差示扫描量热法2种不同原理的方法对2,3,4-三氯苯甲醚标准物质纯度定值及不确定度评定,并采用液相色谱标准添加的方法确认了2,3,4-三氯苯甲醚标准物质中的主要杂质2,3,6-三氯苯甲醚。定值结果为99.56%± 0.40%（k=2）。     

西洋参中人参皂苷Rg1、Re、Rb1基体标准物质的研制

建立高效液相色谱法和高效毛细管电泳法,对研制的西洋参基体标准物质中人参皂苷Rg₁、Re、Rb₁含量进行准确定值,同时考察了样品的均匀性、稳定性和样品的最小取样量,最后对标准物质的不确定度进行了评定。评定结果为人参皂苷Rg₁、Re、Rb₁含量分别为（1.72±0.14）mg/g、（15.3±1.5）mg/g、（25.8±2.8）mg/g,相对扩展不确定度分别为8.4％、10％、11％,可为西洋参的质量控制提供依据。     

颗粒计数标准物质定值方法研究

为了探讨颗粒计数标准物质研究中缺乏操作性强、量值溯源可靠的颗粒计数标准物质定值方法等主要技术难点,本文中采用量值可溯源至长度基准的显微图象分析仪,配以血球计数板为球形乳胶颗粒计数标准物质定值,在确定标准值同时对于定值的不确定度进行了分析和研究。研究结果表明:采用这种方法的定值不确定度优于10%(k=2)。     

Measurement uncertainty in the determination of total petroleum hydrocarbons (TPH) in soil by GC-FID

In this investigation two methods were used for estimating the measurement uncertainty due to sampling and analysis of petroleum hydrocarbon contaminated soil. Analysis of variance (ANOVA) was used for type A evaluation of the measurement uncertainty. The results showed that the statistical evaluation of measurement uncertainty can be complicated by the log-normality and heteroscedasticity of the data. Although mathematical transformation of raw data is widely suggested for overcoming the discrepancy between data and ANOVA assumptions, its use results in problems with the interpretation of the ANOVA results at the original scale.

The measurement uncertainty was also estimated from the calculated precision equations for sampling and analysis. Comparison of measurement uncertainty values with the equivalent values obtained with ANOVA revealed that ANOVA overestimates the expanded uncertainty at both low and high TPH concentrations. Consequently, correct selection of the statistical analysis method needs comprehensive knowledge of the assumptions and limitations of statistical methods and careful consideration of the special characteristics (distribution, constancy of measurement variance) of the raw data as these may affect the validity of the estimated uncertainty. The expanded uncertainty obtained in this study for the results of TPH determinations with linear measurement precision modelling was moderate, ranging from 21% at a TPH concentration of 895 mg/kg to 9% at a TPH concentration of 10 019 mg/kg. If a single sample taken in a survey is analyzed only once, then the analytical variance contributes the most to the measurement variance, ranging from 68– 80% at a TPH concentration of 100–10 000 mg/kg.     

化妆品中丙烯酰胺标准物质配制及不确定度的评定

大多数化学检测采用相对法,因此保证分析结果的有效溯源性,标准物质起重要作用,近些年来基体标准物质在分析检测结果质量控制中的作用更是越来越被分析者重视。该文分别研究了水剂、霜剂类基体化妆品中丙烯酰胺标准物质的配制方法,并对配制过程的不确定度进行了评价,通过建立数学模型,分别对各分量进行评定,计算合成不确定度,取置信概率P=95％,包含因子k=2,从而计算得扩展不确定度为0．04μg／g。     

Determination of methylmercury and butyltin compounds in marine biota and sediments using microwave-assisted acid extraction,solid-phase microextraction,and gas chromatography with microwave-induced plasma atomic emission spectrometric detection

A method is described for the determination of methylmercury and butyltin compounds in marine sediment and tissue using microwave-assisted acid extraction or digestion and solid-phase microextraction (SPME) followed by analysis using gas chromatography with microwave-induced plasma atomic emission spectrometric detection (GC-MIP-AES). Using the SPME-GC-MIP-AES method, enrichment factors for methylmercury and butyltin compounds of 50-100 were achieved, as compared to the typical hexane extraction, and measurements in marine tissue and sediment matrixes were possible at 1-2 microg/kg (methylmercury) and 10-100 ng/kg (butyltins). The SPME-GC-MIP-AES method was validated using several marine sediment and tissue matrix certified reference materials (CRMs) with certified values for methylmercury and butyltin compounds. The SPME-GC-MIP-AES method was used to measure methylmercury in four marine tissue CRMs ranging from oyster tissue at 13.0 +/- 1.0 microg/kg to fish tissue at 397 +/- 13 microg/kg (as Hg dry mass). Results from the SPME-GC-MIP-AES method were used in conjunction with results from other techniques to assign certified values for methylmercury in oyster, mussel, and fish tissue CRMs. Mono-, di-, and tributyltin were measured in three sediment CRMs at concentration levels of (0.08 +/- 0.03)-(0.35 +/- 0.05) mg/kg (as Sn dry mass).