固相萃取-气相色谱/质谱联用法测定卷烟主流烟气中的香兰素和乙基香兰素

采用固相萃取-气相色谱/质谱联用技术,建立了一种同时测定卷烟主流烟气中香兰素和乙基香兰素的方法。方法优化了萃取条件,考察了萃取溶剂、萃取时间对检测结果的影响。通过硅藻土固相萃取柱净化并浓缩后,选取DB-HeavyWAX毛细管柱进行目标物分离,以香兰素-d3作为内标,对香兰素和乙基香兰素进行定量分析。结果表明,香兰素和乙基香兰素在浓度0.2~20.0 mg/L范围内具有良好的线性关系,其检出限分别为9.1 ng/支和6.5 ng/支,回收率均在96.3%~107.7%之间。     

高效液相色谱法同时测定香兰素与邻位香兰素

建立了同时测定香兰素和邻位香兰素的高效液相色谱法.考察了流动相组成、柱温等因素对分析效率的影响.在流动相为5% 乙酸-乙腈(60 :40,体积比),流速1.0 mL/min,柱温25 ℃的优化条件下,香兰素和邻位香兰素可在5 min内实现分离.测定结果表明,香兰素和邻位香兰素在10 ～240 mg/L范围内线性关系良好...     

高效液相色谱法测定发酵液中的香兰素

香兰素(vanillin)是具有广泛用途的有机化合物,可用作食品和化妆品的定香剂、调味剂,它也是医药工业重要的原料和中间体。国际和国内市场对天然香兰素的需求不断增长,但仅从香荚兰豆中提取的香兰素已不能满足需求,因此,通过生物技术生产香兰素已经受到广泛的关注。国内对微生物发酵法生产香兰素和相应的检测方法未见报道：本研究建立了测定发酵液中酚类物质的高效液相色谱法。该方法快速、简便、灵敏,其测定结果可用于香兰素发酵生产的过程控制。     

香兰素在玻碳电极上的电化学行为及其循环伏安测定

在pH 7.5的Tris-HCl缓冲介质的底液中,在循环伏安图上在峰电位+0.54 V处可见到香兰素的灵敏的氧化峰.其峰电流Ip与香兰素的浓度在3.286×10-6～3.944×10-4mol·L-1范围内呈线性关系,检出限(3S/N)为1.643×10-6mol·L-1.据此提出了循环伏安测定香兰素的方法,并应用于测定巧克力中香兰素的含量.在巧克力试样中加入不同浓度的香兰素标准,按方法测定以求测定方法的回收率,研究了香兰素在玻碳电极上的电化学行为,结果表明:香兰素的电极过程具有吸附性和不可逆性.     

高效液相色谱法同时测定牛奶中的香兰素与乙基香兰素

建立了同时测定牛奶中香兰素与乙基香兰素含量的高效液相色谱法。首先对样品进行超声提取,再经酸沉淀蛋白质后进行分析。采用Ultimate XB–C18色谱柱,流动相为甲醇–0.01 mol/L磷酸溶液(体积比为30∶70),流速为1.0 mL/min,检测波长为276 nm。香兰素与乙基香兰素在0.5~10μg/mL范围内线性良好,检出限分别为5.68μg/L和12.8μg/L,平均加标回收率分别为99.8%,98.4%。该方法简便,准确度高,重现性好,可用于牛奶中香兰素与乙基香兰素的日常检测。     

介孔分子筛MCM-41负载磷钨酸催化合成香兰素1,2-丙二醇缩醛

以香兰素和1,2-丙二醇为原料,以介孔分子筛MCM-41负载磷钨酸为催化剂,环己烷为带水剂,合成了香兰素1,2-丙二醇缩醛.考察了醛醇物质的量比、反应时间、带水剂用量、催化剂用量及负载量对产率的影响.实验表明,介孔分子筛MCM-41负载磷钨酸是合成香兰素1,2-丙二醇缩醛的理想催化剂,较优反应条件为:n(香兰素)∶n(1,2-丙二醇)=1∶2.4,负载量为50%,催化剂用量为反应物总质量的2.0%,带水剂环己烷15mL,回流反应2.0h,香兰素1,2-丙二醇缩醛的收率达92%以上.     

乙基香兰素的合成

本文报道了应用相转移催化技术合成中间体邻乙氧基苯酚及产物乙基香兰素,考察了反应温度、时间、物料配比等因素对合成的影响,确立了优化条件。同时采用 UV,IR,~1HNMR 和 GC方法对产物进行表征。研究结果显示聚乙二醇相转移催化合成邻乙氧基苯酚,叔胺相转移催化合成乙基香兰素结果满意。邻乙氧基苯酚最高收率达74.5%,乙基香兰素最高收率达73.5%。另外,还对反常 Reimer-Tiemann 反应相转移催化合成乙基香兰素的机制进行了讨论。     

β-环糊精及羟丙基β-环糊精与香兰素包合作用的谱学研究

用^1H-NMR、紫外吸收及荧光光谱研究了香兰素与β－CD和HPβ－CD的包合作用，发现香兰素与HPβ－CD包合时，HPβ－CD的内腔H－3和H－5质子较与β－CD包合时明显移向高场，表明香兰素分子进入HPβ－CD的内腔较深。用Benesi-Hildebrand关系式求得的包合物的平衡常数也证实香兰素分子进入HPβ－CD的内腔较深，所形成的包合物较稳定。     

偏最小二乘法用于食用香料3组分同时光度法测定

乙基麦芽酚、香兰素和乙基香兰素是重要的食品添加剂，广泛用作糖果、饼干、饮料等的增香剂。然而，大剂量使用香兰素等香料有害健康。因此，测定食品中的这些香料具有重要意义。目前，国内外测定这些香料的方法主要有光度法、高效液相色谱法和电化学法等，且大多只进行单组分分析，而该3组分的同时测定尚未见报道。本实验在pH2．87的缓冲溶液中，应用偏最小二乘(PLS)法对乙基麦芽酚、香兰素和乙基香兰素重叠光谱进行解析，据此建立了简便、快速同时测定样品中香料3组分的新方法。     

香兰素在电活化玻碳电极上的电化学行为及其伏安法测定

制备了电活化玻碳电极,并考察香兰素在该电极上的电化学行为。在优化的实验条件下,香兰素在该电极上有良好的电化学响应,其浓度在1.0×10-6～2.0×10-4mol.L-1范围内与氧化峰电流呈良好的线性关系。检测限(S/N=3)为6.7×10-7 mol.L-1。香兰素于电活化玻碳电极表面发生的电极反应是扩散控制的2电子2质子转移过程。该方法操作简便,重现性较好,并应用此法分析了巧克力中香兰素的含量。     

Electrodialysis of Hydrosols of Ultradispersed Diamonds

The electrical conductivity of hydrosols of ultradispersed diamonds was studied. The electromembrane method for cleaning and concentrating of ultradispersed diamonds in hydrosols was considered. The influence exerted by the concentration of the dispersed phase on the electrical characteristics of the cleaning process was analyzed. A mathematical relation making it possible to evaluate the output characteristics of the process and to determine the geometrical characteristics of the apparatus was proposed.     

Influence of electroless nickel plating of hydrogen-absorbing alloys on cycle characteristics of nickel-metal hydride batteries

The effects of electroless nickel plating of a hydrogen-absorbing alloy on the cycle characteristics of a nickel-metal hydride battery were investigated. The cycle life was improved by employing an electroless nickel-plated hydrogen-absorbing alloy for the negative electrode, which retained the same high-rate level and low-temperature characteristics compared to a cell using a non-plated hydrogen-absorbing alloy. The electroless nickel-plated hydrogen-absorbing alloy provided better electrochemical characteristics when its surface was partly and tightly covered by nickel particles under optimal electroless plating conditions.     

Stabilization of the oleic acid-water emulsion with various kraft lignins

The influence of the initial wood species and polymolecular characteristics on the characteristics of the surface of solid-phase lignin was estimated, and the correlation of these parameters with the ability of kraft lignins to stabilize the oleic acid-water emulsion was examined. The kinetics of breakdown of emulsions stabilized with kraft lignin was studied.     

Physicomechanical and Rheological Characteristics of Composite Materials with Organic and Inorganic Fillers

The strength and rheological characteristics of polymer composite materials based on synthetic copolymers and various fillers were studied. The influence of the filler on the characteristics of composites was revealed.     

The effect of irregularity on the dielectric dispersion characteristics of spherical cellular suspension

The dielectric dispersion characteristics of cellular suspensions are fundamentally determined based on the analogy to composite dielectric materials when periodically and discrete arrangement of cells is assumed. However, under native physiological conditions, when flocculation and clamping events usually occur, those assumptions are usually not valid. In the framework of this study, an examination of irregularity effect on the dispersion characteristics of spherical cellular suspensions is presented. Here, the permittivity spectra of the suspensions have been determined by both measurements of living K562 cell suspensions and finite numerical simulations. Based on the measured and simulated spectra, the dispersion characteristics of the suspensions, for several destinies and arrangements of cells, have been quantitatively analyzed using the Havriliak–Negami empirical formula. Generally, a strong correlation between the low dispersion characteristics was observed as the concentration and density of the cells was increased. In addition, all characteristics found to be significantly deviated in comparison to the characteristics of a periodically arrayed suspension. However, when low-dense arrangement was assumed, the correlation found to be much lower when all characteristics found to be less perturbated. Based on a simple model of interacting cells, it is suggested that those deviations are related to intercellular interactions between adjacent cells.     

Sorption properties of adamantane derivatives

The chromatographic behavior of adamantane derivatives as sorbates and sorbents was studied. The retention characteristics of adamantane derivatives and some organic compounds on an adamantylsilicone stationary phase were determined. The effect of various substituents on the chromatographic behavior of the compounds was examined. Correlations between the sorption and structural characteristics of adamantane derivatives were found.     

Macromolecular surfactants for miniemulsion polymerization

The use of polymeric surfactants as stabilizers in miniemulsion polymerization was reviewed. The structural characteristics of reported polymeric surfactants were detailed and compared. The concept of multi-functional polymeric surfactants was evidenced. The specificities brought by polymeric surfactants in the process of miniemulsion polymerization in comparison to molecular surfactants were analysed for the stability of the initial monomer emulsion, polymerization kinetics and characteristics of the obtained latexes. The contribution of polymeric surfactants to the control of the characteristics of the obtained nanoparticles was detailed with regard to the nature of the core material and to the surface coverage. Polymeric surfactants can be seen as powerful tools for the design of original nanoparticles. On the basis of the available data, possible research topics are suggested.     

Sustained-release phenylpropanolamine hydrochloride bilayer caplets containing the hydroxypropylmethylcellulose 2208 matrix. I. Formulation and dissolution characteristics

The purpose of this study was to develop a new sustained-release phenylpropanolamine hydrochloride (PPA) bilayer caplets that consists of an immediate-release portion and a prolonged-release portion containing a hydroxypropylmethylcellulose 2208 (HPMC2208) matrix. Since PPA is a highly water-soluble drug, incorporation of 60% HPMC2208 level in the matrix was required for giving the product a PPA-slow releasing property. Difference in the viscosity grade of HPMC2208 in the matrices did not greatly influence the PPA dissolution characteristics from the matrices. Therefore, we formulated the prolonged-release portion consisting of 10% PPA, 30% excipients, and 60% HPMC2208 (Metolose 90SH4000) into the sustained-release PPA bilayer caplets. The PPA dissolution characteristics from the formulated bilayer caplets showed the prolonged dissolution profile after rapid dissolution and was close to the targeted profile calculated from PPA pharmacokinetics study. The manufacturing methods of the prolonged-release portion and the filling order of the prolonged-release portion in bilayer compression did not significantly affect the PPA dissolution characteristics from the bilayer caplets. The PPA dissolution characteristics from the bilayer caplets was pH independent. Moreover, the PPA dissolution characteristics from the bilayer caplets was not affected by mechanical shear. The sustained-release PPA bilayer caplets is expected to present constant prolonged-release of PPA after rapid dissolution in vivo without dissolution change due to pH and mechanical shear.     

An experimental and molecular-statistical study of the adsorption of the iodobenzene, 2-iodothiophene, and isomeric iodoadamantane molecules on the graphite basal face surface

The thermodynamic characteristics of adsorption of iodobenzene, 2-iodothiophene, and 1- and 2-iodoadamantanes on the surface of graphitized thermal carbon black were determined experimentally. The influence of the special features of the molecular structure of the adsorbates on the thermodynamic characteristics of adsorption was studied. The atom-atom approximation of the semiempirical molecular-statistical theory of adsorption was used to calculate the thermodynamic characteristics of adsorption of the adsorbates using the newly determined potential function parameters of pair intermolecular interaction (φ(r)) of I with C atoms of the basal graphite face. For the example of isostructural monohalogenated benzenes, thiophenes, and adamantanes, a comparative analysis of the contributions of the F, Cl, Br, and I atoms to the thermodynamic characteristics of adsorption was performed for the nonspecific adsorption of these compounds on a plane graphitized carbon black surface.     

Graphical analysis of Rutherford backscattering spectra

A graphical method was developed to relate data from Rutherford backscattering spectrometry to sample characteristics, such as thickness and concentration profiles. The method was then applied to analyze these characteristics of a gold film.