Determination of unsulphonated quinoline yellow in soft drinks by solid-phase spectrophotometry

A spectrophotometric method for determination of quinoline yellow spirit soluble (QYSS) in the presence of sulphonated quinoline yellow water soluble (QYWS) in soft drinks at trace levels is reported. The method is based on the fixation of QYSS on C-18 silica gel, followed by measurement of its absorbance at = 418 nm in the solid phase after being packed in a 1-mm cell. The applicable concentration range was 1.5–15.0 ng/ml, the detection limit 0.4ng/ml and the relative standard deviation 5.2%. The method was applied satisfactorily to the determination of this compound in samples of commercial soft drinks.     

TG-MS characterization of the reaction products of cadmium yellow and malachite artist’s pigments

The deleterious interaction of some traditional sulphide artists pigments and copper ions results in the formation of black copper sulphides, in particular, covellite (CuS), and, hence, the discolouration of valuable artworks. In this paper the interaction of malachite, a source of copper(II) ions, with the pigment cadmium yellow, a sulphide pigment comprising of a solid solution of cadmium and zinc sulphides, is investigated by XRD and TG-MS. XRD showed the presence of the copper sulphide and cadmium carbonate phases, produced by a simple ion exchange mechanism. TG-MS showed the complexity of the range of metastable phases produced. The identification of these phases, however, requires further work.     

A thermodynamic study of the inclusion processes of α- andβ-cyclodextrins with the acid forms of methyl orange and methyl yellow

The effect of temperature on the UV-visible spectra of the acid forms of methyl orange and methyl yellow in the presence of - and-cyclodextrins was analysed in terms of 1 : 1 inclusion processes. Three inclusion processes were considered for each azo dye/cyclodextrin system. The processes are the apparent inclusion process, the ammonium inclusion process, and the azonium inclusion process. The values of H ⁰ and S ⁰ are reported for each process. The inclusion complexes of the ammonium tautomer are more stable than those of the azonium tautomer and -cyclodextrin inclusion complexes are more stable than those of-cyclodextrin. The inclusion processes resulted in a shift in the position of the tautomeric equilibrium of an azo dye. A significant color fading was observed in -cyclodextrin/methyl yellow solutions. No measurable changes in the absorbances were observed in the case of azo dye solutions containing -cyclodextrin.     

铅铬黄粒子的微胶囊化及其表面形貌的表征

研究了铅铬黄粒子的微胶囊化及其机理；探讨了对粒子表面形貌的量化表征方法．结果表明，在油包水（Ｗ／Ｏ）乳液中对铅铬黄粒子进行无机微胶囊化是一提高其耐酸、碱性的有效方法．颜料粒子的表面形貌可用其表面分形维数（Ｄ）量化表征．     

Ag doped α-Fe2O3 nanoparticles: Synthesis,characterization and application as heterogeneous photocatalyst for removal of organic dye from aqueous media without any oxidizing agents

α-Fe₂O₃ and Ag doped α-Fe₂O₃ nanostructures were synthesized by wet chemical reflux method. XRD analysis established formation of α-Fe₂O₃ phase for un-doped nanostructures while for Ag-α-Fe₂O₃ the diffraction peaks shift slightly towards higher angle. FESEM suggests the development of fine nanostructures with particle size order of 40–70 ​nm for pristine α-Fe₂O₃ NPs, whereas comparatively larger size NPs with order of 60–110 ​nm for Ag-α-Fe₂O₃. The NPs were used as photocatalysts for degradation of eosin yellow and malachite green dyes in aqueous medium under visible light irradiation. Ag-α-Fe₂O₃ NPs efficiently decolourize about 98% dye molecules within 90 ​min.     

A spectrophotometric determination of the formation constants of the inclusion complexes ofα- andβ-cyclodextrins with the azonium and ammonium tautomers of methyl orange and methyl yellow

The color fading caused by the addition of-cyclodextrin or-cyclodextrin to an aqueous solution of a tautomeric mixture of methyl orange or methyl yellow is studied spectrophotometrically at pH 1.1 and 25.0°C. A model involving 1 : 1 stoichiometry has been used to analyze the spectrophotometric data. The addition of a cyclodextrin shifts the tautomeric mixture towards the side of the ammonium tautomer. An expression allowing the calculation of the tautomeric equilibrium constant of the inclusion complexes is derived. The formation constants of the inclusion complexes of the individual tautomers are determined. Both- and-cyclodextrins bind the ammonium tautomer stronger than the azonium tautomer. The inclusion complexes of-cyclodextrin are more stable than the corresponding ones of-cyclodextrin.     

反相高效液相色谱法同时测定果汁中8种添加剂

建立了反相高效液相色谱法（ＲＰ－ＨＰＬＣ）同时直接测定进口果汁中柠檬黄和苋菜红等８种添加剂含量的方法。色谱柱为Ｈｙｐｅｒｓｉｌ　ＢＤＳ　Ｃ１８柱（２５０ｍｍ×４．０ｍｍｉ．ｄ,５μｍ）,流动相为甲醇／０．０１ｍｏｌ／Ｌ乙酸铵,梯度洗脱,流速为 １．０ ｍＬ／ｍｉｎ,柱温为 ４０℃,ＤＡＤ紫外检测器波长为 ２３０ ｎｍ。在此色谱条件下,各组分在１０ ｍｉｎ内均得到良好分离。平均回收率为 ９０％～１１４％,相对标准偏差 １．３％～８．０％。     

绿色和黄色银胶的光化学制备及其共振散射光谱研究

研究了不同光源、光照时间、反应物浓度等对绿色银胶形成的影响,分别制备了绿色银胶和黄色银胶.透射电镜显示,它们的平均粒径分别为100nm和40nm.绿色银胶在393.9nm和713.3nm处有两个吸收峰;黄色银胶在419.3nm处有一较宽的吸收峰.它们的最强共振散射峰位于470nm处;绿色银胶在340nm和80nm还有两个小共振峰.     

吸附剂对柱色谱法分离荧光黄和碱性湖蓝BB效果的影响

吸附剂是影响柱色谱分离效果的重要因素,研究了几种常见的吸附剂如硅胶、碱性氧化铝、中性氧化铝、酸性氧化铝等对柱色谱法分离荧光黄和碱性湖蓝BB分离效果的影响,利用NH3-TPD及N2吸附-脱附分别表征了吸附剂的酸分布及孔分布,采用密度泛函方法计算了荧光黄和碱性湖蓝BB分子的尺寸,并分析了吸附剂酸性、结构与分离效果的关系。实验结果显示硅胶的分离效果好于氧化铝。并且,用硅胶作吸附剂时荧光黄先被洗脱,与氧化铝作吸附剂的洗脱顺序相反。实验过程有利于学生理解吸附剂的作用,加深对柱色谱法的理解,培养严谨、认真的科学态度,提高分析问题解决问题的能力,具有重要意义。     

日落黄与牛血清白蛋白相互作用的电化学研究

利用微分脉冲伏安法,研究了日落黄与牛血清白蛋白之间的相互作用.试验结果表明,日落黄与牛血清白蛋白之间形成近似1:1的复合物,从而造成日落黄峰电流的降低,两者之间的结合主要依靠静电力,且结合常数随温度升高而降低.研究有利于从分子水平上了解日落黄和牛血清白蛋白之间的结合作用,为更进一步了解日落黄的生物代谢机理提供一定的理论参考.