稻谷整精米率标准样品研制

参照GB/T 15000.1-15000.9<标准样品工作导则>的要求进行了稻谷整精米率标准样品的研制.研究了颗粒类物质稻谷特定参数整精米率标准样品制备的原料选择、匀质(混匀)、均匀性试验、定值试验的过程.在本试验条件下,用人工和多级分样器混匀样品,可以得到均匀度合格的样本,经由多个实验室定值,分别得到籼稻整精米率标准样品理论真值为(45.8±1.4)%,粳稻理论真值为(74.6±1.2)%的结果.标准样品的制备为实验砻谷机、实验碾米机的校验和考核以及整精米率检验的质量控制提供了参照物.     

饲料标准样品的制备与定值研究

本文介绍以玉米、豆粕、麸皮为原料，通用于猪鸡鸭鱼等饲料标准样品的制备和定值方法及其均匀性和稳定性的研究。该标准样品已通过鉴定，被批准为国家饲料标准样品，并开始向全国推广使用。     

苎麻精干麻实物标准样品制作均匀性分析

阐述了苎麻精干麻的定义及其标准样品制作目的,标准样品的加工过程及均匀性分析,为今后制作苎麻精干麻实物标准样品程序化提供了科学依据。     

晚籼米加工精度标准样品的研制

加工精度是大米产品的主要定等指标,也是大米贸易中定价的基础。加工精度不仅反映大米的外观品质,而且影响大米的食用品质。以符合GB1350-2009中等质量稻谷为原料,按照《标准样品工作导则》（GB/T 15000.1-15000.9）和《大米》（GB/T 1354-2018）的有关要求,选择《粮油检验 大米加工精度检验》（GB/T 5502-2018）中仪器检测法检验标准样品的留皮度。对大米加工精度样品开展均匀性、稳定性检验和定值及不确定度评估。研制出的晚籼米加工精度标准样品用于大米加工厂家的生产指导,也可用于第三方实验室人员考核、质量控制、仪器校准。     

卷烟感官标准样品新旧定值的对比分析

为准确把握《卷烟》国家标准的感官技术要求,顺利实现新老国标的平稳过渡,采用统计技术对卷烟感官标准样品的新旧定值进行了对比分析。结果表明,新定值与旧定值相比,各定值项目间的正相关性均有所提高,其中刺激性与其它定值项目间的正相关性有较大幅度提高;对香气、杂气、刺激性和余味4个项目的分辨率提高;各定值项目对标样的区分度有所变化,如刺激性对高、中、低档标样的区分度有所提高;对于总分定值,高档标样略有提高,低档标样略有下降,中档标样持平。     

山羊绒细度校准标准样品均匀性及一致性评价

将平均细度为15．71～35．37μm的Interwoollab羊毛细度标准样品用于校准测试平均细度大多在16μm以下的国产山羊绒的仪器不尽合理,为此研制了由GSB02—2769—2011山羊绒细度标准样品与平均细度适宜的In—terw0011ab羊毛标准样品合成的组合校准标样。为分析该组合校准标样用于不同测试方法时的一致性,采用GSB02—2769—2011山羊绒细度标准样品和该组合校准标样分别在3种不同的检测仪上作对比试验;结果表明,两者的均匀性均符合样品的均匀性要求;该试验表明,该组合校准标样在分别3种不同测试仪上的试验结果具有一致性,该组合校样既可行又可靠,可以弥补Interwoollab羊毛细度标准样品用于羊绒纤维细度检测校准细度范围时的不足。     

标准样品及其特性

给出了标准样品的定义，介绍了标准样品的溯源性概念、标准样品的标准化特性、均匀性及其检验、稳定性及其检验和标准样品的定值方法。     

铀同位素标样基体材料铀含量定值研究

对经过均匀化处理的八氧化三铀物料,在分析样本总体上均匀地截取三个层面,在每一个层面按相隔120°的角度径向随机确定三个取样径向点,使用自动电位滴定法对铀含量进行均匀性检验,采用F检验法和S_H值检验组间差显著性,对铀同位素标样进行了均匀性检验数据分析,检验结果表明,铀同位素标样的铀含量分布不均匀性指标■均小于0.1%,满足物理设计要求。对标准样品比对定值中引入的随机不确定度和系统不确定度进行评估、合成,当置信度为95%时,铀含量的相对不确定度为0.065%,其测量不确定度已达到美国同类标准样品水平的测量不确定度水平。     

芝麻素标准样品的研制

依据GB/T 15000.3—2008《标准样品工作导则》,研制芝麻素标准样品。以芝麻为原料,采用高速逆流色谱法分离制备芝麻素单体,通过UV、IR、MS和NMR等手段进行结构表征,同时进行薄层色谱鉴别和热重分析。芝麻素样品进行了均匀性检验、稳定性检验和8家实验室联合定值。结果表明:该样品均匀性良好,在0~4℃条件下储存36个月稳定性良好,定值结果确定其标准值为99.73%,置信度95%的不确定度为0.20。成功研制出了芝麻素国家标准样品,达到了GB/T 15000.3—2008规定的技术要求,样品具有溯源性,可用于芝麻素及相关产品的质量控制和检测方法评定。     

粗脂肪标准物质的制备及均匀性和稳定性研究

用全麦粉作为粗脂肪标准物质的基体,对粗脂肪标准物质的制备程序和工艺以及标准物质的均匀性和稳定性进行了研究。采用粉碎、混匀、干燥、分装、Co-60辐照灭活(辐照量为2.5Mrad)全麦粉粗脂肪标准物质的制备工艺。粗脂肪标准物质样品的均匀性检验结果经F检验以及14个月稳定性监测结果经t检验表明,单元内和单元间均匀程度以及标准物质样品的稳定性均达到国家一级标准物质的制备要求。     

Aflatoxin M1 in milk powders: Processing, homogeneity and stability testing of certified reference materials

As part of the certification campaign of three candidate reference materials for the determination of aflatoxin M₁ (AfM₁) in whole milk powders, homogeneity, short- and long-term stability tests of naturally contaminated milk powders have been performed. The homogeneity of two AfM₁-contaminated milk powders was studied by taking samples at regular intervals of the filling sequences and analysing in triplicate for their AfM₁ contents by liquid chromatography with fluorescence detection (LC-FLD) using random stratified sampling schemes. The homogeneity testing of an AfM₁ 'blank' milk powder material was performed by determining the nitrogen content because AfM₁ levels were below the limit of detection of the most sensitive determination method. The short-term stability of AfM₁-contaminated milk powders was evaluated at three different storage temperatures (4, 18 and 40°C). After storage times of 0, 1, 2 and 4 weeks, samples were investigated using LC-FLD. The long-term stability study comprised of measurements after 0, 6, 12 and 18 months after storage at -20 and 4°C. Analyses were done by LC-FLD. Based on the homogeneity tests, the materials were sufficiently homogenous to serve as certified reference materials. Corresponding uncertainty contributions of 0.23-0.89% were calculated for the homogeneity. The stability measurements showed no significant trends for both short- and long-term stability studies. The long-term stability uncertainties of the AfM₁-contaminated milk powders were 7.4 and 6.3%, respectively, for a shelf-life of 6 years and storage at -20°C. Supplementary stability monitoring schemes over a long period of several years are currently ongoing.     

大豆油脂肪酸成分标准物质的研制

对大豆油脂肪酸成分做了均匀性检验、稳定性监测和定值工作。结果表明,单元内和单元间均匀程度以及标准物质样品的稳定性均达到国家一级标准物质的制备要求。大豆油脂肪酸标准物质的定值结果为：棕榈酸（C16∶0）是11.0±0.8（%）;硬脂酸（C18∶0）是4.5±0.4（%）;油酸（C18∶1）是20.7±1.0（%）;亚油酸（C18∶2）是54.2±2.4（%）;亚麻酸（C18∶3）是8.9±1.8（%）。     

葵花籽油脂肪酸成分标准物质的研制

选取当年产葵花籽油作为标准物质的试验样品,对研制的葵花籽油脂肪酸成分标准物质做了均匀性检验、稳定性监测和定值工作。葵花籽油脂肪酸成分标准物质样品的均匀性检验结果经F检验以及19个月稳定性监测结果表明,单元内和单元间均匀程度以及标准物质样品的稳定性均达到国家一级标准物质的制备要求。葵花籽油脂肪酸标准物质的定值结果为:棕榈酸(C16:0)6.1±0.4;硬脂酸(C18:0)5.6±0.5;油酸(C18:1)23.8±1.4;亚油酸(C18:2)62.2±1.5;亚麻酸(C18:3)1.0±0.7;山嵛酸(C22:0)0.8±0.2。     

Production of a certified reference material for the acrylamidecontent in toasted bread

The need for a certified matrix reference material (CRM) of acrylamide in a food type matrix was emphasized by the competent authorities as a tool to improve comparability, ensuring accuracy and traceability of analytical results. The institute for reference materials and measurements (IRMM) responded to the international request by producing a certified reference material, ERM-BD273, containing endogenous acrylamide in a toasted bread matrix. This work describes the production of the CRM, according to 2 and 3 [ISO Guide 34 (2000). General requirements for the competence of reference materials producers; ISO Guide 35 (2006). Reference materials – General and statistical principles for certification], which comprises the material processing, homogeneity and stability assessment, material characterisation and the acrylamide mass fraction value assignment in toasted bread. Heterogeneity of the material between the vials processed was determined by an in-house validated gas chromatographic methodology involving acrylamide derivatisation and mass spectrometric detection and found to be below 2%. Potential degradation during storage was also investigated and a shelf-life based on this value was established. A collaborative study for material characterisation involved sixteen laboratories applying different analytical methodologies including gas chromatography or high resolution liquid chromatography and isotopic dilution mass spectrometry. The certified value for acrylamide in ERM-BD273, traceable to the international system of units (SI), is (425 ± 29) ng g⁻¹.     

浅谈能力验证数据在DIN磨耗标准样品研制中的应用

比对分析了不同配方加工的"硫化橡胶或热塑性橡胶耐磨性能的测定(旋转辊筒式磨耗机法)"(简称DIN磨耗测试)能力验证样品(样品1和样品2)与国外DIN标准参照胶的质量损耗平均值、标准差和相对标准偏差等数据,结果表明:两种DIN磨耗测试能力验证样品和国外DIN标准参照胶在质量损耗特性量值和样品均匀性上还存在一定的差距.在剔...     

Feasibility study for producing a carrot/potato matrix reference material for 11 selected pesticides at EU MRL level: Material processing, homogeneity and stability assessment

The feasibility for producing a matrix reference material for selected pesticides in a carrot/potato matrix was investigated. A commercially available baby food (carrot/potato-based mash) was spiked with 11 pesticides at the respective EU maximum residue limits (MRLs), and further processed by either freezing or freeze-drying. Batches of some 150 units were produced per material type. First, the materials were assessed for the relative amount of pesticide recovered after processing (ratio of pesticide concentration in the processed material to the initially spiked pesticide concentration). In addition, the materials’ homogeneity (bottle-to-bottle variation), and the short-term (1 month) and mid-term (5 months) stability at different temperatures were assessed. For this, an in-house validated GC-EI-MS method operated in the SIM mode with a sample preparation procedure based on the QuEChERS (“quick, easy, cheap, effective, rugged, and safe”) principle was applied. Measurements on the frozen material provided the most promising results (smallest analyte losses during production), and also freeze-drying proved to be a suitable alternative processing technique for most of the investigated pesticides. Both the frozen and the freeze-dried material showed to be sufficiently homogeneous for the intended use, and storage at −20 °C for 5 months did not reveal any detectable material degradation. The results constitute an important step towards the development of a pesticide matrix reference material.     

鱼肉中氟苯尼考标准样品的制备

研究鲤鱼鱼肉基质中氟苯尼考的标准样品制备方法。通过添加氟苯尼考养殖鲤鱼获得样品基质,用液相色谱串联质谱法对样品的均匀性和稳定性进行检测,通过8 家实验室协作定值的方式对标准样品进行定值和不确定度评估,结果表明样品的均匀性良好,稳定性可达36 个月,可以用于水产品中氟苯尼考残留检测质量控制和相关的科研需要。     

Proficiency test for the determination of heavy metals in mineral feed. The importance of correctly selecting the certified reference materials during method validation

In 2008, the International Measurement Evaluation Programme, IMEP®, organised two proficiency tests (PTs) for the determination of heavy metals in mineral feed, named IMEP-105 and IMEP-27, respectively. IMEP-105 was organised in support of the activities of the European Union Reference Laboratory for Heavy Metals in Feed and Food, and participation was restricted to the officially nominated National Reference Laboratories (NRLs). IMEP-27 was open to all interested control laboratories in the field. The test material used in the two PTs was the same and the timeframe of the two exercises overlapped. The measurands in both exercises were total Cd, Pb and As and extractable Cd and Pb, as defined in Directive 2002/32/EC of the European Parliament and the Council on undesirable substances in animal feed. Forty-nine laboratories from 25 countries reported results to the two exercises, 29 to IMEP-105 and 20 to IMEP-27. In both PTs, external reference values were used instead of consensus values derived from the participants' results. It was shown that the concentration of total and extractable Cd according to Directive 2002/32/EC were identical, while the concentration of extractable Pb was ～80% of total Pb. The main outcome of these comparisons was that an underestimation of the concentrations of the addressed measurands, in particular total Pb, took place due to an erroneous estimation of the bias of the analytical methods used by most of the participants. It appeared that the nature of the certified reference materials chosen for method validation and recovery estimation was the cause of the problem (insufficient matching of the matrix characteristics between these materials and the test sample). No significant difference between the results reported to IMEP-105 and to IMEP-27 was observed.     

Certification of the reference material of water content in water saturated 1-octanol by Karl Fischer coulometry,Karl Fischer volumetry and quantitative nuclear magnetic resonance

Certified reference materials (CRMs) of water content are widely used in the calibration and validation of Karl Fischer coulometry and volumetry. In this study, the water content of the water saturated 1-octanol (WSO) CRM was certified by Karl Fischer coulometry, volumetry and quantitative nuclear magnetic resonance (Q NMR). The water content recovery by coulometry was 99.76% with a diaphragm-less electrode and Coulomat AG anolyte. The relative bias between the coulometry and volumetry results was 0.06%. In Q NMR, the water content of WSO is traceable to the International System (SI) of units through the purity of internal standard. The relative bias of water content in WSO between Q NMR and volumetry was 0.50%. The consistency of results for these three independent methods improves the accuracy of the certification of the RM. The certified water content of the WSO CRM was 4.76% with an expanded uncertainty of 0.09%.