差示扫描量热法对芝麻酚纯度标准物质的定值

建立了采用差示扫描量热法对芝麻酚纯度标准物质的定值及不确定度评价的数学模型、有效检测技术和分析方法.采用差示扫描量热法测量芝麻酚样品纯度的实验条件为升温速率3.0 K/min,称样量3.4～4.7 mg,炉内气体为静态空气.对通过均匀性检验和长期稳定性考察的芝麻酚纯度标准物质进行定值和不确定度评价,同时采用高效液相色谱...     

没食子酸丙酯纯度标准物质的研究

研制了没食子酸丙酯纯度标准物质。依据国家《一级标准物质研制技术规范》,采用高效液相色谱(HPLC)法和差示扫描量热(DSC)法对没食子酸丙酯纯度标准物质进行联合定值,进行了相应的不确定度评定。研制的没食子酸丙酯纯度标准物质定值结果为(99.8±0.5)%(k=2,P=0.95)。该标准物质可用于相关药品生产及使用单位的质量控制和分析方法确认评价。     

2,4,6-三氯酚纯品原料纯度定值方法研究

对用于溶液标准物质制备的纯品原料2,4,6-三氯酚纯度定值方法进行了探讨。采用气相色谱质谱法(GC–MS)对主成分和杂质进行定性鉴定。用高效液相色谱法(HPLC–DAD)、气相色谱法(GC–FID)和差示扫描量热法(DSC)3种不同原理的方法对主成分定值。卡尔费休法测量水分,电感耦合等离子体质谱(ICP–MS)测量无机杂质。2,4,6-三氯酚纯度定值结果为99.3%,扩展不确定度为0.6%(k=2)。     

基于凝固点下降的高纯有机物纯度定值技术研究进展

介绍凝固点测量方法的研究进展。阐述了凝固点下降技术用于高纯有机物纯度定值的基本原理和适用条件,详细介绍了静力学方法和动力学方法这两种凝固点的测量方法,并介绍了两种方法在纯度定值方面的应用情况,且对两种方法的特点进行了对比,展望了凝固点下降纯度定值技术的发展趋势。     

茶碱标准物质的研制与定值

建立了茶碱标准物质的制备和定值方法.将市售茶碱原料纯化、干燥、混匀后.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%置信范围内样品的均匀性良好;稳定性检验按短期稳定性(1月)和长期稳定性(12月)分别进行,长期稳定性结果通过了T检验,表明在20℃条件下茶碱的稳定期不少于12个月....     

甲基苯丙胺标准物质的定值与不确定度分析

为了建立法庭科学毒品检测量值溯源体系,研制了甲基苯丙胺纯度标准物质。通过红外光谱、质谱法对甲基苯丙胺样品进行定性分析,优化并建立了高效液相色谱(HPLC)、差示扫描量热法(DSC)两种定值分析方法。采用热重分析法和电感耦合等离子体质谱法测定水分和无机离子的含量。通过均匀性与稳定性检验结果表明,甲基苯丙胺标准物质的均匀性良好,稳定性至少1年,同时对其进行了不确定度评定。研制的甲基苯丙胺标准物质的纯度为99.8%,扩展不确定度为0.2%(k=2)。     

美雄酮甲醇溶液标准物质的定值及不确定度评定

针对目前食品中兴奋剂类药物检测的需求,研制了美雄酮甲醇溶液国家级标准物质.通过对经筛选的市售原料纯品进行液相色谱-质谱和红外光谱定性分析后,研究利用高效液相色谱法(HPLC)和差示扫描量热法(DSC)对美雄酮蛋白同化类固醇类兴奋剂原料进行纯度定值.利用HPLC在245nm监测,以水(含0.1%HAc)+乙腈=50+50...     

差示扫描量热法测定除草剂绿麦隆的纯度

研究了用差示扫描量热法(DSC)测定绿麦隆的纯度。该法测定最佳条件为升温速率0.5 K.min-1,样品量2~3 mg,保护气流速20 mL.min-1。用本法测得绿麦隆原药的纯度为98.35%,相对标准偏差(RSD)为0.034%,测定结果与已知纯度相符。并将测定结果与高效液相色谱(HPLC)法进行了比较。该法具有操作简便,样品用量少,准确度和精密度均较高等优点。     

多种分析方法测定邻氯代苯亚甲基丙二腈的纯度

采用差示扫描量热单峰法对邻氯代苯亚甲基丙二腈(西埃斯)的纯度进行了测定,通过对升温速率的优化,采用密闭不锈钢耐压池,降低了西埃斯本身挥发性的影响,获得了不同质量样品的纯度值,并与高效液相色谱、气相色谱-质谱和核磁共振等方法的测定结果进行了比较。结果表明:差示扫描量热单峰法、高效液相色谱法、气相色谱质谱法和核磁共振法测定的纯度值分别为99.89%、99.92%、99.25%和95.0％,测定结果最大相差4.92％。 并讨论了不同分析方法产生偏差的原因。     

差示扫描量热法测定马来酸酐纯度

用差示扫描量热法（DSC）测定马来酸酐的纯度,测定条件为升温速率0．8℃／min,样品量2．6～2．8mg,氮气流速为40mL/min。纯度测定结果的相对标准偏差（RSD）为0．02％（n=5）。将DSC法、液相色谱法、药典法、滴定分析法对不同物质纯度的测定结果进行了比对,4种方法的测定结果基本一致。DSC法简便、快速、准确、重现性好,适合马来酸酐纯度的测定。     

黄芩素纯度标准物质的定值及其不确定度评定

为了满足食品及医药等领域的检测需求,研制了黄芩素纯度标准物质。采用液相色谱–质谱法和红外光谱法对黄芩素纯度标准物质原料定性后,利用高效液相色谱法(HPLC)和定量核磁技术(Quantitative Nuclear Magnetic Resonance Spectroscopy,QNMR)对黄芩素的纯度进行了定值,并用HPLC法对黄芩素纯度标准物质进行了均匀性检验和稳定性考察。对定值结果的不确定度进行了评价,研制的黄芩素纯度标准物质的定值结果和扩展不确定度分别为98.8%,0.8%(k=2)。     

Development of a Water Matrix Certified Reference Material for Volatile Organic Compounds Analysis in Water

Water matrix certified reference material (MCRM) of volatile organic compounds (VOCs) is used to provide quality assurance and quality control (QA/QC) during the analysis of VOCs in water. In this research, a water MCRM of 28 VOCs was developed using a “reconstitution” approach by adding VOCs spiking, methanol solution into pure water immediately prior to analysis. The VOCs spiking solution was prepared gravimetrically by dividing 28 VOCs into seven groups, then based on ISO Guide 35, using gas chromatography-mass spectrometry (GC-MS) to investigate the homogeneity and long-term stability. The studies of homogeneity and long-term stability indicated that the batch of VOCs spiking solution was homogeneous and stable at room temperature for at least 15 months. Moreover, the water MCRM of 28 VOCs was certified by a network of nine competent laboratories, and the certified values and expanded uncertainties of 28 VOCs ranged from 6.2 to 17 μg/L and 0.5 to 5.3 μg/L, respectively.     

定量核磁法测定CL-20标准物质中有机杂质的含量

采用定量核磁共振波谱法(qNMR)测定六硝基六氮杂异伍兹烷(CL-20)标准物质中有机杂质的含量。核磁谱图解析证明,主要有机杂质成分为残余溶剂乙酸乙酯和中间体五硝基-乙酰基六氮杂异伍兹烷(MPIW),以不含四甲基硅烷(TMS)的氘代丙酮为溶剂,将六甲基二硅醚的四氯化碳标准溶液加入待测液中作为内标,以其谱峰(δ=0.06)作为内标峰对两种有机杂质进行定量分析。考察了延迟时间和采样次数对准确定量的影响,结果显示为确保定量结果的准确性,延迟时间D_1应不小于20 s,采样次数为32次。采用优化后的实验参数进行纯度分析,测得CL-20标准物质中有机杂质乙酸乙酯和MPIW的质量分数分别为0.03516%和0.156 2%,相对标准偏差(RSD)分别为0.91%和0.86%。     

Effects of filler–polymer interactions on cold‐crystallization kinetics in crosslinked,silica‐filled polydimethylsiloxane/polydiphenylsiloxane copolymer melts

Crystallization in a series of variable crosslink density poly(dimethyl‐diphenyl)siloxanes random block copolymers reinforced through a mixture of precipitated and fumed silica fillers has been studied by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), nuclear magnetic resonance (NMR), and X‐ray diffraction (XRD). The silicone composite studied was composed of 94.6 mol % dimethoylsiloxane, 5.1 mol % diphenylsiloxane, and 0.3 mol % methyl‐vinyl siloxane (which formed crosslinking after peroxide cure). The polymer was filled with a mixture of 21.6 wt % fumed silica and 4.0 wt % precipitated silica previously treated with 6.8 wt % ethoxy‐end‐blocked siloxane processing aid. Molecular weight between crosslinks and filler–polymer interaction strength were modified by exposure to γ‐irradiation in either air or in vacuo. Isothermal DMA experiments illustrated that crystallization at ?85 °C occurred over a 1.8 hour period in silica‐filled systems and 2.2–2.6 hours in unfilled systems. The crystallization kinetics for irradiated samples were found to be dependent on crosslink density. Irradiation in vacuo resulted in faster overall crystallization rates compared to air irradiation for the same crosslink density, likely due to a reduction in the interaction between the polymer chains and the silica filler surface for samples irradiated in air. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 1898–1906, 2006     

The effect of proton irradiation on the melting and isothermal crystallization of poly(ether‐ether‐ketone)

Amorphous poly(ether‐ether‐ketone) (PEEK) progressively crosslinks on irradiation with 11.0 MeV protons, and this has a marked effect on the extent of crystallinity that subsequently develops and on the kinetics of the high temperature isothermal crystallization. The extent of crystallinity with time was analyzed using the Avrami equation, and the temperature dependence of the rate constants was analyzed in terms of nucleation theory. While irradiation inhibits the overall rates of crystallization by the reduction in the mobility of the chain segments as observed by the progressive increase in the glass transition temperature, it also alters the fold surface free energy. The observed melting points were consistent with depression of the equilibrium melting point by the crosslinks produced by irradiation. These two effects alone are sufficient to account for the inhibition of crystallization on irradiation of PEEK by protons. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 1094–1103, 2008     

香米特征香味成分2-乙酰基-1-吡咯啉提取及检测方法研究进展

2-乙酰基-1-吡咯啉(2-AP)是目前已经探明的香米特征性香味成分,其含量的高低直接影响香米的品质与价格,但由于该成分在天然香米中的含量通常低至微克每千克,在采用现代分析检测方法测定时,还可能受到样品基质干扰、色谱分离共流出等问题的影响,因此,如何从稻米样品中高效提取该化合物并结合适当的检测方法进行精确测定具有一定的挑战性。该文综述了对稻米中2-AP进行测定时常用的样品前处理方法及仪器分析方法。样品前处理方法主要有蒸馏法、萃取法及顶空富集法等;仪器分析方法主要包括气相色谱及气相色谱-质谱法、气相色谱-嗅觉测试法,以及最新被开发出来的衍生化-高效液相色谱-串联质谱法。该综述将为食品贸易领域香米中2-AP的测定、农业领域香米的遗传育种及水肥管理、食品加工领域米香类稳定风味成分的开发等提供参考依据。