激光小角光散射测定高聚物的分子量

本工作建议了一种比较方便可行的、用已知瑞利因子的溶剂标定激光小角散射光度计的方法。纯溶剂的瑞利值R_θ与其散射强度比(G_θ/G_0)有如下关系:R_θ/n=φ[(G_θ/G_0)-δ],式中n为溶剂折光指数;φ为仪器常数;δ为与背景有关的参数。以已知瑞利值的甲苯、苯、环己烷、氯仿及四氯化碳的R_θ/n对测定的(G_θ/G_0)值作图,得到了较好的线性关系,从直线斜率可定φ值。以此方法标定的仪器测定了十个聚苯乙烯窄分布试样均得到了满意的结果。     

凝胶化反应全过程的激光光散射跟踪研究

在苯乙烯（Ｓｔ） 二乙烯苯（ＤＶＢ）自由基共聚的凝胶化反应过程中定时取样，得到凝胶化点前后及至终点的一系列样品，然后用激光光散射技术，包括研究散射光强及其角度依赖性的静态光散射（ＳＬＳ）和研究散射光频移的动态光散射（ＤＬＳ），表征了这系列样品的重均分子量Ｍｗ、均方旋转半径Ｒｇ、第二维利系数Ａ２及流体力学半径Ｒｈ等静、动态参量及这些参量的变化规律，定量地描述了凝胶化反应全过程     

胺甲基聚丙烯酰胺相对分子质量的光散射测定

本文首次实现了聚电解质(PAM)的沉淀分级,以小角激光散射法成功地进行了重均相对分子质量的测定并订定了有实际应用价值的M-H方程。     

建筑用梳形共聚物分散剂溶液行为的光散射研究

采用激光光散射研究了一种主链为聚丙烯酸侧链为聚乙二醇的梳形共聚物分散剂的一些溶液行为.从静态光散射得出了较为合理的表观重均分子量、均方旋转半径等参数.动态光散射给出了流体力学半径分布及其角度和浓度依赖性.结合静态和动态光散射,上述梳形共聚物分散剂在溶液中的构象也得到初步的表征.通过与描述梳形聚合物的Gay-Raphae模型进行比较表明,这类梳形共聚物溶液在低盐离子和低pH值条件下存在聚集行为,形成以PAA主链为核PEG为壳层的类胶束聚集.     

激光小角光散射仪测定高聚物分子量时溶液浓度的选择

激光小角光散射仪(LALLS)由于采用了激光光源,在光强、单色性和准直性等方面都有很大改进、测定可在小角度下(2°—7°)进行,不需对散射角外推(如作Zimm图^[1]),测量计算简便,而且在测定较低和较高分子量时,比常规光散射仪有更高的精确度,因此近年来已成为高聚物表征的有效手段。     

高效液相色谱测定烟草制品中的维生素E

建立一种超声辅助萃取高效液相色谱测定烟草制品中维生素E的方法.样品用饱和抗坏血酸乙醇溶液萃取,采用ZORBAX Extend-C18色谱柱(150 mm×4.6 mm,5 μm)及FLD检测器在激发波长为298 nm、发射波长为325 nm下检测,流动相为100%甲醇,采用外标法定量.线性相关系数为0.999 96,信噪比为3时检出限为0.12 μg/mL,回收率为96.4%,相对标准偏差为0.7%(n=6).研究表明,烤烟型烟草中维生素E含量远高于晒烟、白肋烟及香料烟;烤烟型卷烟烟丝比混合型卷烟烟丝中维生素E含量高;烟草制品中梗丝和烟草薄片的维生素E含量较低.     

介电损耗法测定卤化银乳剂微晶体的离子电导

卤化银乳剂层在交变电场中显示出介电色散现象(Maxwell-Wagner效应),即在交变电场的频率f不同时,卤化银乳剂层的介电损耗ε″也不相同。根据ε″～1f,曲线可以计算卤化银微晶体的离子电导σ₂。我们注意到,不同类型的明胶具有不同的介电常数ε′₁,同一明胶在不同频率和真空度下所显示的ε′₁也有差别。含湿量的增大使乳剂的ε″_max,ε′_max和ε_∞的数值增大,使ε″～1gf曲线的低频端提高,使f_max向低频偏移。通过抽气严格控制样品含湿量是得到准确的σ₂的关键。此外,我们还考察了乳剂层的层数和电极的尺寸对f_max和σ₂值的影响。     

κ-卡拉胶热可逆凝胶化行为研究

用固体小角激光散射方法研究κ 卡拉胶 (KC)的热可逆凝胶化行为 .以散色斑点的突停点温度为体系的凝胶化点Tgel,考察了溶液中加入Na+ ,K+ ,NH+4,Ca2 + ,Cu2 + ,Zn2 + 等抗衡离子对Tgel的影响 .结果是随抗衡离子浓度增大Tgel上升 ;Tgel与Na+ 的浓度呈线性关系 ,与K+ ,NH+4,Ca2 + ,Cu2 + ,Zn2 + 等离子浓度的平方根成线性关系 ;另外 ,还得到 30℃时KC在KCl盐溶液中的溶胶 凝胶相图 ,并对比了KC在NaCl溶液中透析前后Tgel的变化 .     

CONTINUOUS ABSORPTION OF TOLUENE VAPOR BY MICELLAR SOLUTIONS AND THE RESULTING MICROEMULSIONS

ABSTRACT

Microemulsions consisting of AOT-H₂O-toluene-hexyl carbitol (HC) or butyl carbitol (BC) were investigated in relation to the relative vapor pressure of toluene (P/P_o). The microemulsions generally revealed high (P/P_o). The relatively lower (P/P_o) was only obtained from those containing 10% and 15% AOT at higher levels of HC and BC respectively. From the linear plot of (P/P_o) against the volume fraction of toluene, the transition from micellar solution to microemulsion was evident. This transition phenomenon was also observed in the continuous absorption of toluene vapor. It was concluded chat the microemulsions studied were not efficient in scrubbing toluene vapor, but they were much more effective than their respective micellar solutions.     

激光散射研究单价盐对C8-卵磷脂胶团形成的影响

用激光散射测量确定C_8-卵磷脂临界胶团浓度及其随温度、盐离子的变化。从中导出了胶团分子量, 形成因子, 能量梯级间隔以及标准焓等反映该溶液内分子相互作用的重要参量, 从而导出单价盐调控胶团大小以至形成和解体的规律和方法。     

铬天青S共振光散射法测定脱氧核糖核酸

介绍在阳离子表面活性剂十六烷基三甲基溴化铵(CTMAB)存在下阴离子染料铬天青S(CAS)共振光散射(RLS)法测定脱氧核糖核酸(DNA)的方法。在pH=5．27的六次甲基四铵一盐酸缓冲溶液中，研究了CAS—CT-MAB—yDNA体系的RLS光谱特征、影响因素和最佳反应条件。在最佳条件下，体系的RLS强度增加值△I与yDNA的浓度在50～800μg／L和1000～2000μg／L呈线性关系，其线性回归方程分别为△I=0．48c 2．56和△I=0．14c 17．86，相关系数分别为0．9997和0．9991，检出限为4．3ng／mL。该方法简便、快速，应用于合成样品中yDNA的测定，测定结果的相对标准偏差为2．93％～4．71％，回收率为97．8％～105．2％。     

十六烷基三甲基溴化铵增敏砂罗铬花青R共振光散射法检测DNA

在pH=3．92的三羟甲基氨基甲烷-HCl缓冲溶液中,阳离子表面活性剂十六烷基三甲基溴化铵对砂罗铬花青R与脱氧核糖核酸(DNA)的共振光散射(RLS)有协同增强作用。考察了影响因素,研究了在优化条件下RLS强度与DNA浓度之间的关系,鱼精DNA和小牛胸腺DNA的线性范围均为0．05—3．00mg／L,检出限分别31．03、35．98μg/L,回收率为97．9％～99．6％,测定结果的相对标准偏差为0．5％-2．1％。     

INDIRECT DETERMINATION OF MERCURY BY ATOMIC ABSORPTION SPECTROPHOTOMETRY USING ZINC HOLLOW CATHODE LAMP

Abstract

An indirect atomic absorption spectrophotometric method for mercury has been developed on the basis of solvent extraction chemistry. Mercury(II) was converted into a bromo-complex anion and extracted into 1,2-dichloroethane with the 2,2′-bipyridyl-zinc chelate cation. The resulting zinc in the extract, which was equivalent to a specific amount of mercury, was determined by atomic absorption spectrophotometry. The sensitivity for the determination of mercury could be enhanced to the level of zinc by the proposed method.     

涂锆石墨管石墨炉原子吸收法测定锗

本文研究了石墨炉原子吸收法测定锗的条件。试验了某些金属盐对测定锗的基体改进效应以及应用涂锆石墨管的效果。实验证明,应用涂锆石墨管可使测定锗的灵敏度提高约4.5～5倍,原子化出现温度从应用普通管时的2050K降低到1540K,消除了记忆效应。此时,锗的原子化机理可能是氧化锗被碳化锆还原,然后金属锗蒸发。提出了氯化锗用苯萃取后苯层进样的锗的分析方法。本研究可应用于煤灰中高于0.5ppm锗的测定。     

DETERMINATION OF PARAMETERS OF EXCITED STATES OF DNA and RNA BASES BY LASER UV PHOTOLYSIS

Abstract— The mechanism of photodecomposition of nucleic acid bases in a neutral aqueous solution upon two-step excitation of high-lying electronic states by a powerful laser UV radiation is discussed. Experimental dependences of photodecomposition efficiency versus UV radiation intensity are measured both under picosecond and nanosecond laser UV irradiations. By comparison of experimental dependences with a theoretical model, we obtain some characteristics of excited states, such as lifetime t₁ of the first electronic excited state S₁ intersystem crossing yield φ, photosensitivity from an intermediate excited state and others for all five nucleic acid bases.     

小角激光光散射法测定聚甲基丙烯酸-6-磺己基钠特性粘数-分子量关系

<正> 聚甲基丙烯酸己磺酸钠(PSSHMA)是我们最近合成的,具有较好的抗凝血性能。对于带磺酸基聚合物抗凝血性能的研究,文献报道还不多。我们用羟基己磺酸钠与甲基丙烯酸反应制备了甲基丙烯酸己磺酸钠(SSHMA)新单体,在此异相酯化反应中,使用了四丁基硫酸氢铵(TBAB)作为催化剂,使反应较顺利的进行,得纯单体。经复钙时     

INVESTIGATION OF POWER ABSORPTION BY METHYLENE BLUE IN A LIGHT SCATTERING MEDIUM WITH AN INTERNAL PHOTODYNAMIC ACTINOMETER

Abstract— Power absorption by aqueous solutions of methylene blue containing high concentrations of polystyrene microspheres was measured at 650 nm, using the photosensitized inactivation of subtilisin Carlsberg as an internal actinometer. The results were analyzed with the one-dimensional diffusion approximation for a finite slab. It is shown that the power absorption is determined by two macroscopic parameters, the optical penetration depth and the linear absorption coefficient. The optical penetration depth was determined independently by measuring flux profiles with an inserted fiber-optic method. The results are in satisfactory agreement with the predictions of the diffusion model, with microsphere diameters from 0.5 to 5 μm and a wide range of scatterer and dye concentrations. The presence of the scatterers diminished the power absorbed by the dye in all cases. The predictions of one-dimensional diffusion model are compared to Kubelka-Munk theory, and shown to be equivalent for optically dense systems     

巯基棉吸附分离法测定水中铬,镍

探讨了巯基棉在不同吸附条件下对水中Ｃｒ＾６＋、Ｎｉ＾２＋的定量吸附，并用原子吸收分光光度法分别测定其含量。巯基棉吸附效率高，定量解脱完全，待测元素的分离富集选择性强。此法灵敏度高，误差小。     

液膜富集原子吸收分光光度法测定痕量钪

液膜富集原子吸收分光光度法测定痕量钪李龙泉孙晔淦五二李亚栋（中国科技大学应用化学系合肥２３００２６）关键词钪液膜原子吸收分光光度法液膜分离法具有简便、快速、选择性好、富集倍数和回收率高等优点。王雨春［１］等曾将其用于钪的分离；但未见用于痕量钪分离、富...