A New Flow Instrument for Conductance Measurements at Elevated Temperatures and Pressures: Measurements on NaCl(aq) to 458 K and 1.4 MPa

A new flow electrical conductance instrument was constructed and tested on dilute NaCl solutions up to 458 K, and on more concentrated solutions (maximum 0.436 mol⋅kg⁻¹) at 373 K. The results of the new instrument agreed with those of previous authors within the estimated experimental errors. The model of Bernard et al. (J. Phys. Chem. 96, 3833–3840 (1992), MSA) was found to represent the high-temperature results without introducing an ion-pairing equilibrium constant. The Fuoss–Hsia conductance equation as given by Fernandez-Prini was found to represent the dilute concentrations with Λ° (NaCl) as the only adjustable parameter. It was found that Λ° (NaCl) could be expressed as a function of solvent viscosity and density by using three parameters found by regression of literature results between 278.15 and 523 K. This equation along with the FHFP theory permits the equivalent conductivity of dilute sodium chloride solutions to be calculated within the accuracy of the existing experimental measurements.     

气相色谱-质谱联用法测定维生素C泡腾片中的甜蜜素

采用气相色谱-质谱(GC-MS)选择离子监测法(SIM),建立了准确可靠、灵敏度高、快速简便的测定维生素C泡腾片中甜蜜素含量的新方法.样品中的甜蜜素衍生后用有机试剂提取,在选择离子模式下进行测定,以保留时间和特征离子比例进行定性,单离子定量.甜蜜素的线性范围为0.05-10mg/L,检出限为0.6mg/kg,回收率为90.5%-96.9%,相对标准偏差小于4.4%.方法分析所用时间短,结果准确可靠,选择性好,适用于维生素C泡腾片中甜蜜素含量的检验.     

Phase diagram of Na2S2O3 + ethanol + water at ambient pressure and temperature

In the present communication, we report the studies concerning liquid–liquid–solid equilibria for the ternary system sodium thiosulphate (Na₂S₂O₃) + ethanol + water at ambient pressure and at room temperature (303 ± 2 K). The solubility data of Na₂S₂O₃ are reported for solutions in water, ethanol and solutions of varying concentrations of ethanol in water. The phase diagram for the said system is developed, described and compared with similar system K₂CO₃ + methanol + water. These results have been explained in terms of structural properties of aqueous ethanol solutions and further discussed in terms of the effect of ions to cause phase separation.     

基于褐藻酸钠-纳米金复合物作非酶标记的新型电化学免疫传感器的研制

比较了用三碘甲状腺氨酸抗体(T3抗体)、褐藻酸钠(AS)标记T3抗体及褐藻酸钠-纳米金复合物(ASN)标记的T3抗体,在通过免疫反应结合到免疫电极表面后,引起的电极表面微环境发生改变的程度;用Fe(CN)3-/4-6为电化学探针,用循环伏安法获取金电极表面微环境改变的电流信息来检测 T3抗体,检测的线性范围为100～1 600ng·ml-1,检出限为45ng·ml-1.     

The study of the partitioning mechanism of methyl orange in an aqueous two-phase system

An aqueous two-phase system of dodecyl triethylammonium bromide (C₁₂NE, cationic surfactant) and sodium dodecyl sulfate (SDS, anionic surfactant) mixture is proposed for the extraction of some dyes and porphyrin compounds. Transparent two phase-systems are formed when the surfactant concentrations and C₁₂NE/SDS ratios are in certain regions. In this study, the aqueous two phase-systems were prepared by mixing 0.1 mol l⁻¹ C₁₂NE and SDS with a molar ratio of 1.7:1.0. The results showed that negatively charged chlorophyll (sodium copper chlorophyllin) and positively charged dye (methyl violet) were efficiently extracted into the upper phase. The negatively charged methyl orange (pH>7) was moved into the upper phase mostly while amphoteric methyl orange (pH<3) was distributed in the two phases uniformly. Except for hydrophobic force, charge interaction between solute and surfactant also play an important role in the extraction process.     

β沸石的铝化

β沸石自1988年结构被确定以来受到普遍重视,由干结构上的特殊性,G沸石既具有较强酸性又具有明显的碱性［‘,‘］．但q佛石的高硅铝比使其在化学组成上对碱性的贡献甚微,如果能降低其硅铝比,则有可能获得具有较强碱性的佛石分子筛．直接合成的o佛石,硅铝比一般在10以上．     

碲氢化钠与胺烷基化苯并三氮唑的反应

碲氢化钠是一个用途广泛的磁试剂,自作为有用的去溴试剂以来,日益受到化学工作者的关注,不断有文献报道它的合成及应用.例如能有效地还原卤代烃、硝基化合物、叠氮化合物和亚胺等.近年来,Katritzky报道了胺烷基化苯并三氮唑衍生物的合成及应用,此衍生物中的苯并三氮唑基是很好的离去基团,易被各种亲核试剂所取代.我们在前文中对硒氢化钠与胺烷基化苯并三氮唑反应生成二苄基二硒醚的合成进行了报道.本文用碲氢化钠与胺烷基化苯并三氮唑反应,结果生成还原产物N-取代胺.     

流动注射比浊法测定人体体液中钾

基于四苯硼钠与钾作用产生浊度 ,探讨并优化了流动注射分析条件 ,从而建立了测定人体体液中钾的新方法。方法简便、快速 ,每小时进样 6 0次 ,线性范围为 1.0× 10 - 4～ 1.0× 10 - 3mmol·ml- 1,所测尿样和血样的相对标准偏差分别为 3.0 8%和 2 .6 3%。     

氨基酸与钠离子非共价键相互作用的电喷雾质谱研究

实验研究中常常观察到钠离子与一些多肽或蛋白质有较强的非共价键结合能力,这种非共价键相互作用可能与生物的一些功能和活性有关。为了进一步了解这一结合作用,我们应用电喷雾质谱研究了常见的20种氨基酸与钠离子在溶液中的非共价键相互作用。实验研究中发现脯氨酸和苯丙胺酸与钠离子有较强的非共价键结合能力。     

钠硼硅酸盐玻璃分相及浸析的NMR研究

用多种ＮＭＲ方法，包括＾２９Ｓｉ、＾２３Ｎａ，＾１１Ｂ ＭａＳ及＾２９Ｓｉ ＣＰ／ＭＡＳ ＮＭＲ，研究了一定组成的ａ２Ｏ－Ｂ２Ｏ３－ＳｉＯ２三元体系玻璃在不同温度下分相处理２４小时及用酸浸析处理后的结构变化。结果表明，在低于分相上界临界温度的范围内，存在着一个温度转折点，低于这一温度时，受动力学因素影响，分相未达平衡态，温度愈低，距平衡态愈过，分相愈下完全。超过这一温度，分相可达平衡态，受热力学控