Analysis of USP Organic Volatile Impurities and Thirteen Other Common Residual Solvents by Static Headspace Analysis

Static headspace gas chromatography was investigated for the analysis of residual solvents in size-limited samples. The advantages of improved limits of detection at low ppm levels and decreased sample size requirements were realized. This methodology allows the measurement of 18 common residual solvents in 6 min using 1 mg or less of sample. Greater recovery of analytes from pure dissolution solvents without the use of salts became possible when smaller preparations of samples were combined with the use of smaller vials. Rapid equilibration of the static headspace sample preparations was an additional benefit of this modification. Optimized chromatography was developed to take advantage of the shorter equilibration time and to increase instrument productivity.     

Comparison of the Efficiency of Mass Exchange in the Complex Model for Highly Volatile and Nonvolatile Components

The efficiencies of mass exchange in the complex model have been compared for two variants of representation of the running equation of the equilibrium line: y = m x and y = a x + b. Based on the processing of experimental data on separation of the benzene–toluene mixture in cross motion of the flows, it has been shown that the first equation is adequate only for small variations in the concentrations at the step of massexchange while the second equation has a more universal character.     

顶空气相色谱质谱法同步测定污水厂中17种挥发性有机物

探讨了顶空气相色谱质谱法测定水中挥发性有机物的影响因素,确定含盐量为3g/10m L,瓶平衡时间为45min,炉温为70℃为试验的最优化条件。实验结果表明,在10-160μg/L范围内,检出限均介于9-13μg/L,线性关系良好(r均大于0.9994);120μg/L的城市污水厂样品加标回收率均在85-101%范围内,相对标准偏差均小于5%(n=6)。该方法用于测定13家污水厂进出水中17种挥发性有机物,结合各污水厂消毒工艺,旨在寻找更为安全的尾水消毒工艺。     

不同包装材料对酱肉挥发性风味物质的影响

目的 研究酱肉在PET/AL/PE铝箔包装、PET/PE透明包装条件下不同时间段的挥发性风味物质的变化。方法 采用顶空固相微萃取–气相色谱–质谱连用法(SPME–GC–MS)并结合相对气味活度值(ROAV)、主成分分析(PCA)对酱肉挥发性风味物质变化进行分析。结果 研究发现,酱肉中挥发性物质主要为酯类、醇类,其中苯甲酸乙酯、乙酸芳樟酯、癸酸乙酯、正己酸乙酯、(+)–柠檬烯、壬醛、正己醛、(–)–4–萜品醇、桉叶油醇、芳樟醇、乙基麦芽酚、茴香脑的ROVA值大于1,为关键风味物质。PCA分析得出,2–甲基丁酸乙酯、(E,E)–2,4–壬二烯醛、正己酸乙酯、2,5–辛二酮、(1R)–2,6,6–三甲基双环[3.1.1]庚–2–烯、3–甲硫基丙醛、异丁酸乙酯、茴香脑为特征性挥发性风味物质。另外,通过对在PET/AL/PE铝箔和PET/PE透明包装下,酱肉各类风味物质含量、主体香味物质和异味物质ROVA值、主成分分析的比较,说明不同包装材料对酱肉挥发性风味物质的成分、含量均有影响。结论 从长期检测的结果看出,PET/AL/PE铝箔包装比PET/PE透明包装可显著地阻止脂肪氧化,较少生成异味物,可更好地保护酱肉的香味,为酱肉的贮藏保鲜提供了依据。     

顶空气相色谱法测定P（NIPAM-CO-MMA）体系中甲基丙烯酸甲酯及其水解产物残留量

目的：建立测定P（NIPAM-CO-MMA）体系中的甲基丙烯酸甲酯及其水解产物残留量。方法：采用顶空进样毛细管气相色谱法,HP-INNOWAX毛细管柱,以氮气为载体,用FID检测器,测定P（NIPAM-CO-MMA）体系中的甲基丙烯酸甲酯、甲基丙烯酸和甲醇的含量。结果：3种有机溶剂完全分离,浓度在考察范围内有良好的线性...     

A Comparison of Evolutionary Algorithms for Mechanical Design Components

Two evolutionary algorithms - the genetic algorithm and the evolution strategy - are compared in respect of mechanical design problems. Mechanical design problems are real world problems, characterized by a number of inequality constraints, nonlinear equations, mixed discrete-continuous variables and the presence of interdependent discrete parameters whose values are taken from standardized tables. The selection, recombination and mutation operators, and the chosen constraint-handling method are presented for both the genetic algorithm and the evolution strategy. In order to find the best combination of operators for each algorithm which will solve mechanical design problems, a number of selection and recombination operators are compared in respect of these problems. A comparison of these two algorithms with regard to three mechanical design problems extends the results of comparisons presented in the literature for unimodal and multimodal test functions with continuous variables only, and without constraints.     

顶空气相色谱法测定脉络宁注射液中有机溶剂残留量

本文应用顶空进样方式,DB-624毛细管柱分离,FID检测器,外标法定量测定脉络宁注射液中乙醇,乙酸乙酯残留量,结果2个组分完全分离,分离度为19.0。在所考察的线性范围内具有良好的线性关系。乙醇、乙酸乙酯的相关系数R分别为0.9995、0.9997,平均回收率分别为97.59%、96.85%,重现性分别为1.6%、3.3%,检测限分别为0.18μg/mL、0.007μg/mL。     

顶空气相色谱法测定盐酸法舒地尔中有机溶剂残留量

本文应用顶空进样方式,DB-624毛细管柱分离,FID检测器,外标法定量测定盐酸法舒地尔中乙醚,甲醇,二氯甲烷残留量,结果3个组分完全分离.分离度为甲醇,乙醚之间为19.0,乙醚和二氯甲烷之间为20.8.在所考察的线性范嗣内具有良好的线性关系,相关系数r分别为甲醇0.9993,乙醚为0.9997,二氯甲烷为0.9963...     

顶空-气相色谱法测定水中乙醛、丙烯醛和丙烯腈

建立了顶空-气相色谱法测定水中乙醛、丙烯醛和丙烯腈的分析方法。该方法分离度好,灵敏度高,水中乙醛、丙烯醛和丙烯腈的检出浓度为0.03mg/L、0.07mg/L、0.04mg/L,回收率分别为86%~115%、81%~110%、80%~108%。结果表明,顶空-气相色谱法测定水中乙醛、丙烯醛和丙烯腈方法简单快捷,准确,适合地表水、废水中乙醛、丙烯醛和丙烯腈的同时测定。     

三种竹叶中挥发性成分分析及对比研究

目的 研究对比苦竹、麻竹、紫竹竹叶中的挥发性成分,旨在开发新型抗菌抗氧化成分资源,为天然安全的抗菌抗氧化包装及保鲜技术开发提供基础。方法 采用水蒸气蒸馏法提取3种竹叶挥发油成分,并用气相色谱-质谱联用（GC-MS）技术结合保留指数（RI）对挥发油成分进行鉴定分析。结果 从3种竹叶挥发油中分别鉴定出61,49,68种挥发性成分,以酯类（16.358%～31.930%）、酮类（18.206%～24.033%）、烃类（3.873%～19.632%）、醛类（8.436%～15.414%）和醇类（8.448%～11.182%）化合物为主。3种竹叶挥发油含24种相同成分,以棕榈酸异丙酯（9.826%～22.408%）、4-羟基-3-甲基苯乙酮（5.870%～7.078%）、苯乙醛（3.746%～4.486%）等为主。结论 3种竹叶挥发油相同成分均相对含量较高,这些含量较高的物质均有良好的抗菌抗氧化特性。     

顶空固相微萃取气质联用法分析包装印刷品关键气味成分

目的 采用顶空固相微萃取技术（HS-SPME）结合气质联用（GC-MS）技术分析5款包装印刷品中对气味贡献较大的成分。方法 通过考察不同类型的萃取头、平衡时间、萃取时间和萃取温度对挥发性/半挥发性成分的数量及含量的影响,建立一种包装印刷品气味成分检测方法。结合解卷积+匹配度法+保留指数法对检测出的化合物进行定性识别,通过归一化法和内标法对气味成分的含量进行分析,并结合化合物的气味阈值,筛选关键气味成分。结果 得到了最佳的分析条件,采用50/30μm聚二乙烯苯/碳分子筛/聚二甲基硅氧烷固相微萃取头,平衡时间为30 min,萃取时间为30 min,萃取温度为80°C,解吸时间为10min。在上述最优条件下,5款包装印刷品被鉴别出43种关键性气味成分,包括醛类、酮类、醇类、芳香烃类、杂环类、酯类、醚类、胺类等八大类。结论 该方法可为后续包装印刷品气味分析、异味预警、新产品开发、工艺技术改进等提供技术支撑。     

顶空气相色谱法分析饮用水中四氯化碳的测量不确定度评定

本文讨论了顶空气相色谱法分析饮用水中四氯化碳的测量不确定度的主要来源，并对各不确定度分量和测量结果的不确定度进行了评定。     

顶空气相色谱法测定尿素中甲醇

本文采用顶空进样方式,DB-624毛细管柱,FID检测器,测定尿素中甲醇残留量。结果在0.4～200μg/mL质量浓度范围内具有良好的线形关系,相关系数大于0.9999,平均回收率为在92.5%～98.6%之间,变异系数小于2%,检测限为0.2μg/mL。     

Inactivation of Palladium‐based Oxygen Scavenger System by Volatile Sulfur Compounds Present in the Headspace of Packaged Food

An oxygen scavenger based on a catalytic system with palladium (CSP) was recently developed to remove oxygen in food packagings. Although the CSP worked with various types of food, with some foods, an inhibition of the CSP was observed. Because such catalytic systems are susceptible to poisoning by sulfur‐containing compounds, the aim of this study was to understand the inactivation of palladium‐based catalysts in presence of foods containing volatile sulfur compounds (VSCs). To achieve this, the oxygen scavenging activity (OSA) of the CSP was evaluated in presence of selected food products. Afterwards, VSCs mainly present in these foods were exposed to the CSP, and the influence on the OSA was evaluated. Finally, headspace analysis was performed with the diluted VSCs and with the packaged food products using proton transfer reaction time‐of‐flight mass spectrometry. It was found that the catalytic activity of the CSP was inhibited when VSCs were present in the headspace in concentrations ranging between 10.8–36.0 ppbv (dimethyl sulfide, DMS), 1.2–7.2 ppbv (dimethyl disulfide), 0.7–0.9 ppbv (dimethyl trisulfide), 2.1–5.8 ppbv (methional) and 4.6–24.5 ppbv (furfuryl thiol). It was concluded that in packaged roast beef and cheese, DMS may be the compound mainly responsible for the inactivation of the CSP. In packagings containing ham, the key compounds were hydrogen sulfide and methanethiol; in peanuts, it was methanethiol; and in par‐baked buns, an accumulation of methional, DMS, butanethiol and methionol. When potato chips were packaged, it was demonstrated that when VSCs are present in low concentrations, oxygen can still be scavenged at a reduced OSA.     

A Comparison of Three Different Procedures for Estimating Variance Components

An analytic procedure for obtaining variances of estimates of variance components in a general multi-way classification is described. As an application, three methods for estimating variance components are compared for a two-way classification. Since the variances of the estimates are affected by the magnitude of the true variance components (parameters) as well as the arrangement of the subclass numbers (n _ij 's), a numerical tabulation is necessary in order to make a comparison. Using a UNIVAC 1105, the variances of the estimates of variance components are evaluated over a substantial range of parameters and n _ij 's. These results are presented in tabular form for selected sets of parameter values.     

An Investigation of Diffusion in Droplets and of Evaporation of Volatile Components into Vacuum

A numerical investigation is performed of the dynamics of diffusion in droplets and of free-molecule evaporation into vacuum of volatile components of magnesium (Mg) and zinc (Zn) from aluminum alloys. The calculations are performed in application to the conditions of my experiments in high-frequency droplet formation under conditions of centrifugal dispersion in vacuum of rotating (overloads of 70–4000) blanks by the melting method under the effect of a concentrated energy source. In view of analogy between mass transfer and heat transfer, available solutions are used in heat transfer under convection cooling of bodies with boundary conditions of the third kind. It is demonstrated that the numerical values of Biot diffusion criteria (Bi) are functions of the properties of alloy components and do not depend on the initial content of volatile components. At the droplet temperature T = 1000 K and radius R = 0.25× 10^?3 m, the Biot number is Bi = 14.8 for alloying systems Al-Mg and Bi = 74.4 for Al-Zn. The solution demonstrates that the diffusion resistance within droplets causes a several-fold decrease (compared to the initial value) in the transfer of the mass of volatile component to the droplet surface (with a decrease in the flow of vapors) even for the given short time of droplet flight τ = 0.01 s corresponding to the value of the Fourier criterion Fo = Dτ/R² = = 1.2×10^?3. The final depletion of the composition of droplets of magnesium, which is estimated relative to its permissible content in the alloy according to GOST (State Standard), is about 0.07% for a D16 alloy with a wide range of variation of Mg content from 1.2 to 1.8% by mass, which may be regarded as insignificant. For an AMg6 alloy with a smaller range of variation of Mg content from 5.8 to 6.8%, the depletion is about 0.2%, which may be regarded as appreciable.     

离子液体顶空微萃取-气相色谱法测定水中苯系物

采用1-丁基-3-甲基咪唑四氟硼酸盐离子液体([Bmim]BF4)作萃取剂,顶空液相微萃取法富集水中苯系物,气相色谱法测定。考察了不同萃取温度和时间、样品体积、单液滴体积和盐析效应对结果的影响。苯、甲苯、二甲苯检出限分别为0.030μg/L、0.147μg/L、0.180μg/L,结果表明所用离子液体可有效富集水中痕量苯系物。     

顶空气相色谱法测定舒它蓝锌中N.N-二甲基甲酰胺和2-乙氧基乙醇

本文应用顶空进样方式,DB-624毛细管柱分离,FID检测器,程序升温模式,外标法定量测定脂溶性药物(舒它蓝锌)中N.N-二甲基甲酰胺和2-乙氧基乙醇的残留量。结果N.N-二甲基甲酰胺和2-乙氧基乙醇的线性范围分别为10～500μg/ml和2～100μg/ml,相关系数r分别为0.9997和0.9995;回收率分别在98.2%～111.2%和96.1%～107.1%之间,相对标准偏差(RSD)分别为3.9%和1.9%,最低检测浓度均为1.0μg/ml。     

安全气囊织物动态透气性与静态透气性的测试

通过自行设计的安全气囊织物动态透气性测试装置对 2 种不同的锦纶 66 安全气囊织物进行了测试研究, 发现在高压下安全气囊织物动态透气量与压差呈线性关系. 为了与动态透气性进行比较, 还通过 CFP-1100-AI 孔径仪对上述 2 种锦纶 66 安全气囊织物进行静态透气性测试, 发现在高压下安全气囊织物静态透气量与压差呈幂律关系. 对比研究表明: 在相同压差下安全气囊织物的静态透气量大于安全气囊织物的动态透气量, 且随着压差的增加, 安全气囊织物的动态透气量与静态透气量的差值也逐渐增加.     

离心式冷水压缩机组成部件的结构分析和技术特性比较

本文介绍了离心式冷水机组的主要组成部件，包括压缩机和电机，蒸发器和冷凝器，节流装置和抽气装置等，比较了不同机型技术特性的优缺点，为选择适合的离心式冷水机组提供了选型依据。