Simple and Precise Quantification of Iron Catalyst Content in Carbon Nanotubes Using UV/Visible Spectroscopy

Iron catalysts have been used widely for the mass production of carbon nanotubes (CNTs) with high yield. In this study, UV/visible spectroscopy was used to determine the Fe catalyst content in CNTs using a colorimetric technique. Fe ions in solution form red–orange complexes with 1,10-phenanthroline, producing an absorption peak at λ=510 nm, the intensity of which is proportional to the solution Fe concentration. A series of standard Fe solutions were formulated to establish the relationship between optical absorbance and Fe concentration. Many Fe catalysts were microscopically observed to be encased by graphitic layers, thus preventing their extraction. Fe catalyst dissolution from CNTs was investigated with various single and mixed acids, and Fe concentration was found to be highest with CNTs being held at reflux in HClO₄/HNO₃ and H₂SO₄/HNO₃ mixtures. This novel colorimetric method to measure Fe concentrations by UV/Vis spectroscopy was validated by inductively coupled plasma optical emission spectroscopy, indicating its reliability and applicability to asses Fe content in CNTs.     

Determination of ultra-trace gold in natural water by graphite furnace atomic absorption spectrophotometry after in situ enrichment with thiol cotton fiber

A simple method of determining ultra-trace Au in natural water was presented by using graphite furnace atomic absorption spectrophotometry (GFAAS) after in situ enrichment with thiol cotton fiber (TCF). The sample solution was adjusted to pH 1.5-2.0 with HCl, then the water sample was passed through a column packed with 0.10-0.20 g TCF and the flow rate was controlled at 20-40 ml min⁻¹. The effects of interferences, such as complexing and oxidizing agents and other elements adsorbed on TCF were overcome by chemical treatments prior to the desorption of Au. The adsorbed Au was adsorbed with 2.0 ml hot acid, then it was extracted with 1.00 ml methyl isobutylketone (MIBK). For a 5 l water sample, the detection limit of Au is 0.02 ng l⁻¹. The relative standard deviation (R.S.D.) for the determination of 1.44 ng l⁻¹ Au was 9.4%.The method was applied to determine ultra-trace Au both in suspended phase and soluble phase in natural water, the concentrations of total Au in natural water samples range from 0.51 to 67.82 ng l⁻¹. The recovery of added 0.50-6.00 ng l⁻¹ Au was 80-95%. The method is useful in prospecting for Au deposits by means of hydrogeochemical methods. The enrichment is carried out in the field, and then the determination of Au is completed later in the laboratory.     

Crystal Structure of Adduct 2-Phenyl-imidazo [ 4,5-f ] 1,10-phenanthroline Methanol

The structure of the title adduct comprises a phenanthroline derivative 2-phenyl-imidazo[4,5-f]1,10-phenanthroline and a methanol.The composition of the crystalline adduct was characterized as C19H12N4.CH3OH.It belongs to orthorhombic system,space group Pna21 with a=1.3693(4)nm,b=2.2988(7)nm,c=0.51338(15)nm,V=1.6160(8)nm^3.Z=4,and final R1=0.0423.wR2=0.1012 .Crystal structure shows that all the 19 carbon atoms and 4 nitrogen atoms are coplanar.The bond length data indicated that a very extensive conjugation system was formed.This conjugation makes the compound being a potentially excellent energy transformer used for luminescent materials.     

苯并噻唑重氮氨基偶氮苯与汞（Ⅱ）的显色反应及其应用

报道了新试剂苯并噻唑重氮氨基偶氮苯的合成及其与汞（Ⅱ）的显色反应，在ＴｒｉｔｏｎＸ－１００存在下弱碱性介质中，试剂与汞形成２：１的橙红色络合物，最大吸收波长位于５２０ｎｍ处，表观摩尔吸光系数为１．５１×１０＾５Ｌ．ｍｏｌ＾－１．ｃｍ＾－１。汞量在０～１．２ｍｇ／Ｌ范围内遵守比尔定律，直接应用于废水中微量汞的测定，结果满意。     

饮食中微量元素砷的分布规律与人体健康关系

采用催化动力学光度法测定了六大类(共三十种)样品中的总砷含量，探讨了砷在食品中的分布规律，建立了砷在人体中的安全系效和积累系效的效学评价公式，用于评价砷与人体健康的关系，这对人们选择食物有一定的指导意义。     

新席夫碱吡哆醛缩邻氨基酚的合成及其分析应用研究

本文研究了新席夫碱吡哆醛缩邻氨基酚的合成及其分析应用，提出了钒（Ｖ）的分光光度测定法，该法简便，灵敏，选择性好。     

Simultaneous spectrophotometric determination of Zinc(II) and Nickel(II) with 1-(2-pyridylazo)-2-naphthol

A new procedure for the simultaneous spectrophotometric determination of Zn(II) and Ni(II) with 1-(2-pyridylazo)-2-naphthol as chromogenic reagent has been developed. It is based on resolution of the mixed spectrum over the wavelength range 530–590 nm by applying a least-squares fitting program to standard spectra from each component. The spectra are recorded at an apparent pH of 5.0, provided by an acetate buffer in a mixed 6040 v/v 2-ethoxyethanol/water medium. The relative standard deviations for determination of 13.7 g of Ni and 31.0 g of Zn were 1.9 and 1.0%, respectively (8 replications). The method has been applied to the analysis of iron surfaces coated with a Zn-Ni alloy. The results are compared with those obtained by atomic-absorption spectrophotometry.     

比光谱-导数吸光光度法及其应用与进展

综述了比光谱－导数吸光光度法的基本原理、主要试验条件的选择及其在多组分混合物同时测定中的应用与进展。全文共引用了参考文献50篇。     

金－钼酸盐－耐尔蓝缔合显色反应的研究

在聚乙烯醇存在下，金与钼酸盐形成络阴离子，继而与耐尔蓝形成离子缔合物，其最大吸收位于５９５ｎｍ，表现摩尔吸光系数ε值为２．７１×１０￣５Ｌ．ｍｏｌ￣（－１）．ｃｍ￣（－１），线性范围０～１６μｇ／２５ｍＬＡｕ，大多数离子不干扰。用于岩矿和冶金产品中金的测定，结果满意。     

二安替比林（3,4—二甲氧基）苯基甲烷光度法测定茶叶中锰

在碱性介质中，加热时空气氧化Ｍｎ为Ｍｎ，Ｍｎ与二安替比林苯基甲烷反应生成橙色产物，吐温２０和乳酸起到协同增敏作用，λｍａｘ＝４６０ｎｍ，ε＝７．８×１０＾４Ｌ．ｍｏｌ＾－１．ｃｍ＾－１，锰量在０－１２μｇ／２５ｍｌ范围内符合比尔定律。