Fourth-derivative spectrophotometric determination of neodymium in mixed rare earths with methyl thymol blue and cetylpyridinium chloride

A sensitive and selective method is described for the determination of neodymium in mixed rare earths using fourth-derivative spectrophotometry. The method is based on the absorption spectra of 4f electron transitions of the complex of neodymium with methyl thymol blue and cetylpyridinium chloride. The influence of various instrumental parameters and reaction conditions for maximum colour development are investigated. The calibration curve is linear over the range 0–3.5 g ml^–1 neodymium. The relative standard deviation for determination of 1.4 g ml^–1 neodymium (n = 7) is 1.6%. The detection limit (signal-to-noise ratio = 3) is 0.2 g ml^–1.     

A new Fluorimetric Reagent for Highly Selective and Sensitive Determination of Terbium Ion

 In this work, a new ligand, 2,9-bis[N,N-bis(carboxymethyl)-aminomethyl]-1,10-phenanthroline (BBCAP), was synthesized and used to establish a novel fluorimetric method for the determination of trace amounts of terbium in a binary system. Its luminescence mechanism was studied. The excitation and emission wavelengths are 284 nm and 547 nm, respectively. Other rare-earth metal ions in 100-fold excess caused no interference. The fluorescence intensity was a linear function of the concentration of terbium in the range of 5.0 × 10⁻¹⁰–1.0 × 10⁻⁶ mol/L. The detection limit was 2.0 × 10⁻¹¹ mol/L (n = 12). The standard addition method was used to determine the terbium in a synthetic rare-earth sample with satisfactory results. This method represents a direct, rapid, selective and sensitive analytical procedure with a widely linear range. Received November 29, 2001 Revision February 9, 2002     

同步辐射白光全反射XRF在痕量元素检测的初步应用研究

叙述了同步辐射白光全反射Ｘ射线荧光分析的实验装置，给出了几种标准物质ＴＸＲＦ实验的检出限，并对实验结果进行了讨论。     

铕（Ⅲ）—β—二酮—4,5—二氮芴—9—酮三元配合物的合成

铕（Ⅲ）┐β┐二酮┐４，５┐二氮芴┐９┐酮三元配合物的合成成义祥徐端钧＊徐元植（浙江大学化学系杭州３１００２７）关键词铕，β－二酮，二氮芴酮，三元配合物，合成，荧光光谱１９９７－０３－３１收稿，１９９７－０７－１５修回噻吩甲酰三氟丙酮（ＴＴＡ）和苯甲...     

2,2′-(1,2-亚苯基二氧)二(N-苯基乙酰胺)及其稀土配合物的合成、表征与荧光性质

合成了一种新的芳香族酰胺配体2，2’-（1，2-亚苯基二氧）二（N-苯基乙酰胺）及其稀土（La，Eu，Tb，Dy，Sm，Gd）硝酸盐配合物，通过核磁共振谱、元素分析、摩尔电导、红外光谱、差热等测试技术对其进行了结构表征。结果表明，稀土配合物的可能结构为：[REL（NO3）3]·H2O（RE：La^3＋、Sm^3＋、Eu^3＋、Gd^3＋、Tb^3＋、Dy^3＋）．配合物产率约为78％。在稀土配合物中，作为抗衡阴离子的3个硝酸根均以双齿的配位方式与稀土配位，稀土配位数为10，并且还有1个结晶水。在298K下对配合物[EuL（NO3）3]·H2O和[TI）L（N03）3]·H2O的固体荧光性质进行了研究。结果发现，它们分别发射Eu^3＋和Tb^3＋稀土离子的特征荧光，且配合物[TbL（NO3）3]·H2O的荧光比[EuL（NO3）3]·H2O的荧光强。说明此芳香族酰胺配体敏论Tb^3＋发光比敏化Eu^3＋发光程度大。     

流动注射光度法同时测定铜基合金中的铝和铁

提出了同时测定铜基合金中铝和铁的流动注射分析法。以０．０４ｍｏｌ／ＬＨＣｌ作载液，铬天青Ｓ为显色剂，通过测定６２８ｎｍ处铝、铁两配合物的吸光度之和及铝配合物的吸光度，实现了两组分的同时测定。在优化的实验条件下，检测限：Ａｌ和Ｆｅ分别为１．６９×１０－３和１．７３×１０－３ｍｇ／Ｌ，Ａｌ浓度在０～０．８ｍｇ／Ｌ；Ｆｅ浓度在０～１．０ｍｇ／Ｌ时服从比耳定律。进样频率为６０样／ｈ，所拟方法用于实际样品分析，获得满意结果。     

英平诸痹灵药酒中钴,锶,锂含量分析

采用火焰原子吸收分光光度法测定５种英平诸痹灵药酒中钴、锶、锂的含量。结果表明，该类药酒中微量元素Ｓｒ含量较高，微量元素Ｃｏ、Ｌｉ含量较低，该结果为讨论抗类风湿药物中微量元素与治疗类风湿疾病的关系提供了有用数据。     

Two-state irreversible thermal denaturation of anionic peanut (Arachis hypogaea L.) peroxidase

Detailed differential scanning calorimetry (DSC), steady-state tryptophan fluorescence and far-UV circular dichroism (CD) studies, together with enzymatic assays, were carried out to monitor the thermal stability of anionic peanut peroxidase (aPrx) at pH 3.0. The spectral parameters were seen to be good complements to the highly sensitive but integral method of DSC. Thus, changes in far-UV CD corresponded to changes in the overall secondary structure of the enzyme, while changes in intrinsic tryptophan fluorescence emission corresponded to changes in the tertiary structure of the enzyme. The results, supported with data concerning changes in enzymatic activity with temperature, show that thermally induced transitions for aPrx are irreversible and strongly dependent upon the scan rate, suggesting that denaturation is under kinetic control. It is shown that the process of aPrx denaturation can be interpreted with sufficient accuracy in terms of the simple kinetic scheme, , where k is a first-order kinetic constant that changes with temperature, as given by the Arrhenius equation; N is the native state, and D is the denatured state. On the basis of this model, the parameters of the Arrhenius equation were calculated.     

An ultrasensitive method for the determination of thiouracil and phenylthiouracil using capillary zone electrophoresis and laser-induced fluorescence detection

This paper reports the development of a method based on capillary electrophoresis with laser-induced fluorescence detection for the simultaneous determination of thiouracil (TU) and phenylthiouracil (PhTU) with high sensitivity (nanomolar range, i.e., attomoles detected). After derivatization with 5-iodoacetamidofluorescein, the analytes were separated by capillary zone electrophoresis using 20 mM phosphate buffer (pH 10.0) and quantified by fluorescence detection. The linearity range, precision, recovery, and detection limits were determined, and the method was shown to be applicable for the determination of TU and PhTU in spiked feed samples and urine.     

Study on the reaction of triple helix poly(A:2I) with Cu~(2+)

The effect of Cu2+ on the triple-stranded helical structure of poly(A:2I) was studied by means of circular dichroism spectral method with the help of ultraviolet spectral and ethidium bromide fluorescence probe methods. It was found that Cu2+ destabilizes the structure of the triple helix poly(A:2I) and induces its structural transformations, meanwhile, the transformations can be partially reversed by a higher NaCl concentration. The structural transformations may be expressed by the following scheme: poly(A:2I) - poly(A:I) + poly(I)- poly(A) + 2poly(I)