基于电化学电容检测的新型钙离子传感器

通过金-硫共价键,将巯基十六羧酸以自组装的方式固定到金电极表面。再通过EDC、NHS的活化作用,对钙调蛋白的氨基与巯基十六羧酸暴露于自组装层外的羧基进行共价键和,从而将钙调蛋白固定到电极表面,制成一种新型的钙离子电容传感器。首先对传感器进行了等效电路分析,并分别考察了不同浓度电解质溶液对基底电容的影响,确定了进行实验所需的合适电解质浓度。用本实验室自行开发研制的电化学电容分析仪研究了该传感器对钙离子的响应能力,并进一步考察了其再生能力及稳定性。实验结果表明,在10-8~3×10-6mol/L的较宽范围内,钙离子浓度的对数值与总电容信号值之间呈线性关系,而且检出限可以达到10-9mol/L。制备好的传感器浸泡在0.02 mol/L,pH 7.0的磷酸缓冲溶液中在4℃冰箱中可以保存一个月而其对钙离子的响应能力未发现有显著的下降,说明其具有良好的稳定性。使用过的传感器用EDTA进行再生后基底电容的变化不超过0.3%,说明其具有良好的再生可...

纳米GdPO_4:Eu~(3+)的制备、结构和发光特性

采用沉淀法,在不同pH值、EDTA二钠盐参加和不同温度等条件下制备出纳米GdPO4:Eu3+。利用X射线衍射,扫描电镜和荧光光谱等测试手段对制备的纳米GdPO4:Eu3+的结构,形貌和发光性能进行了研究。XRD和SEM研究结果表明:所有样品均为纯GdPO4相,纳米粒子的大小、形貌和晶面的发育与合成条件有关;发射光谱和激发光谱的研究结果表明:5D0-7FJ特征发射峰强度和激发光谱的强度随pH值和烧结温度的提高而增强,EDTA二钠盐参加合成的样品,由于在表面残留有机基团使发光强度降低。纳米粒子的猝灭浓度约为8%(摩尔分数,下同)。

Synthesis and structural characterization of new tungsten(VI) complexes with polycarboxylate ligands

The reactions of (NH4)(2)WS4 and three polycarboxylate ligands {including nitrilotriacetate (nta(3-)), citrate (Hcit(3-)) and ethylenediaminetetra acetate (EDTA(4-))} in H2O/EtOH at ambient temperature have resulted in three new trioxotungsten (VI) complexes, K-3[WO3(nta)]center dot H2O 1, (NH4)(4)[WO3(cit)]center dot 2 H2O 2 and K-2(NH4)(2)[W2O6(EDTA)]center dot 4H(2)O 3, respectively. These three complexes have been characterized by IR, XPS, TGA-DTA, H-1 and C-13 NMR spectroscopy. And their structures have been determined by X-ray crystallographic studies, which confirm that I and 2 are mononuclear compounds and 3 is a binuclear compound. Each tungsten atom in 1-3 is coordinated to three unshared oxygen atoms, which adopt fac stereochemistry, while the remaining fac positions are occupied by three atoms from the ligands. The electrochemical properties of 2 and 3 have been investigated.

Separation of yttrium from heavy lanthanide by CA-100 using the complexing agent

The selective extraction of yttrium front heavy lanthanide by liquid-liquid extraction using CA-100 in the presence of the complexing agent, such as EDTA, DTPA, and HEDTA was investigated. The extraction of heavy lanthanide in the present of the complexing agent was Suppressed when compared to that of Y because of the masking effect, but the selective extraction of Y was enhanced. All complexing agents formed 1: 1 complex with rare earth elements (RE), and only free rare earth ions could take part in the extraction. The condition for separation was obtained by exploring the effects of the complexing agent concentration, the extractant concentration, pH and the equilibration time on the extraction of the heavy rare earth elements.

Selective separation of yttrium by CA-100 in the presence of a complexing agent

The selective separation of Y from yttrium solution containing small heavy rare earth (HRE) impurities (Ho, Er, Tm, Yb, Lu) by liquid-liquid extraction using CA-100 in the presence of a water-soluble complexing agent of ethylenediaminetetraacetic acid (EDTA) was experimentally studied at 298K. Experiments were carried Out in two feeds, Feed-I: [RE](f) = 4.94 x 10(-3) M, Y = 98.5%, HRE (Ho, Er, Tm, Yb, Lu) = 1.5%; Feed-II: [RE](f) = 4.94 x 10(-3) M, Y = 99.9%, HRE (Ho, Er, Tm, Yb, Lu) = 0.1%, as a function of equilibrium pH (pH(eq)), the concentration ratio of [EDTA]:[HRE impurities]. It was shown that the extraction of HRE in the presence of EDTA was suppressed when compared to that of Y because of the masking effect, while the selective extraction of Y was enhanced and the separation factors increased to maximum at appropriate condition for Feed-I: Y/Ho = 1.53, Y/Er = 3.09, Y/Tm = 5.61, Y/Yb = 12.04, Y/Lu = 27.51 at pH 4.37 and [EDTA]:[HRE impurities] = 4: 1, for Feed-II: Y/Ho = 1.32, Y/Er = 1.91, Y/Tm = 2.00, Y/Yb = 3.05, Y/Lu = 3.33 at pH 4.42 and [EDTA]: [HRE impurities] = 8:1. The separation and purification of Y by this method was discussed.

Synthesis and evaluation of novel polysaccharide-Gd-DTPA compounds as contrast agent for MRI

Macromolecular conjugates of two kinds of natural polysaccharides, that from Panax quinquefolium linn (PQPS) and Ganoderma applanatum pat (GAPS), with gadolinium-diethylenetriaminepenta-acetic acid (Gd-DTPA) have been synthesized and characterized by means of FTIR, elementary analysis and ICP-AES. Their stability was investigated by competition study with Ca2+, EDTA (ethylenediaminetetraacetic acid) and DTPA. Polysaccharide-bound complexes exhibit T-1 relaxivities of 1.5-1.7 times that of Gd-DTPA in D2O at 25degreesC and 9.4T. MR imaging of Sprague-Dawley (SD) rats showed remarkable enhancement in rat liver and kidney after i.v. injection of these two complexes: liver parenchyma 60.9+/-5.6%, 57.8+/-7.4% at 65-85 min; kidney 144.9+/-14.5%, 199.9+/-25.4% at 10-30 min for PQPS-GdDTPA, GAPS-Gd-DTPA at gadolinium dose of 0.083 and 0.082 mmol/kg, respectively. Our preliminary in vivo and in vitro study indicates that the two kinds of polysaccharide-bound complexes are potential tissue-specific contrast agents for MRI.

Arabinogalactan as a carrier for contrast agent in magnetic resonance imaging

Arabinogalactan-Gd-DTPA was synthesized by the reaction of diethylenetriaminepenta-acetic acid (DTPA) bisanhydride with polysaccharide in dry DMSO and characterized by FTIR, elemental analysis and ICP-AES. Its stability was investigated by competition with Ca2+, EDTA, DTPA. The t(1)-relaxivity is 8.06 mmol(-1) . L . s(-1) in D2O, 8.48 mmol(-1) . L . s(-1) in 0.725 mmol . L-1 BSA, respectively. t(1)-weighted MR imaging of rat kidney and liver showed a remarkable enhancement post injection of Arabinogalactan-Gd-DTPA. The results indicate that the arabinogalactan-Gd-DTPA is a potential contrast agent for MRI.

Fluorescence spectra of hemorrhagin III from the snake venom of Agkistrodon acutus

Hemorrhagin III (AaH III) was separated and purified from the crude snake venom of Agkistrodon acutus, and its molecule weight was determined accurately to be 23; 284.4 +/- 0.1 by LDI1700-MALDI-TOF-MS. Emission spectra of AaH III showed that Trp residues were located by a great degree in the hydrophobic area. Addition of SDS and guanidine-HCl led to change of the molecular conformation of AaH III, and caused the fluorescence quenching of Trp residues. The red-shifted emission band of AaH III after adding guanidine-HCl showed that Trp residues exposed in polar solvents. The effects of pH, EDTA and metal ions on the fluorescence spectra of AaH III were also investigated.

Determination of 14 rare earth impurities in Y2O3 by petroleum sulfoxide extraction chromatography

Petroleum sulfoxide-NH4SCN extraction chromatography was developed for the separation of Y from other rare earth elements. Some chromatographic parameters were chosen and separation factors between Y and other rare earth elements were determined. A column of resin coated with petroleum sulfoxide was used. The Y in the sample was eluted with NH4SCN, then titrated with EDTA. The recovery was 67%-120% and relative standard deviation +/-4.0%-19.4%. This method can be applied to the determination of trace amounts of rare earth impurities in Y2O3 with a purity of 99.999 9%-99. 999 99%.

Effect of metal ions on Ru(bpy)(3)(2+) electrochemiluminescence

Ethylenediaminetetraacetate (EDTA) was chosen for the investigation of the effect of metal ions on Ru(bpy)(3)(2+) electrochemiluminescence (ECL). Metal ions that are preferentially bound to the oxygen atoms (MIO) have no effect on the intensity of ECL except for Al3+ and Y3+, whereas metal ions that are preferentially bound to the nitrogen atoms (MIN) preclude the oxidation of EDTA and decrease the ECL intensity.

多元校正-紫外-可见分光光度法同时测定铬(Ⅵ)和铬(Ⅲ)

本文研究在pH3.0～4.0,70～80℃加热条件下,Cr(Ⅱ)与EDTA形成紫色络合物,其最大吸收波长为537.5nm,而在此条件下,Cr(Ⅵ)几乎不与EDTA反应,利用Cr(Ⅱ)络合物和Cr(Ⅵ)离子本身吸收光谱间的差异,借助于最小二乘(K—矩阵)法解析两物种吸收光谱的重叠问题,进而建立了多波长同时光度测定Cr(Ⅱ)和Cr(Ⅵ)的方法,用于合成试样、电镀废液及废铬酸洗液中Cr(Ⅵ)和Cr(Ⅱ)的同时测定,获得满意结果.

混合物中稀土元素的NMR法测定

核磁共振检测混合物中的共存金属是新近发展起来的无机分析方法。Fedorov以EDTA和NTA为配体,通过观察络合物Ln(EDTA)和Ln(NTA)_2配体的~1H NMR谱线,率先开展了水溶液中共存稀土元素的同时间接测定研究,这种方法比分别直接检测各稀土核磁核共振信号的方法实用可靠,且方便易行。但采用~1H NMR谱检测水溶液中顺磁稀土离子时,强的溶剂水峰易掩蔽近邻的稀土配合物谱线;某些重稀土配合物的~1H谱线宽,相互重叠,难以用作分

混合稀土中单一稀土元素的化学分析

本文提出以2-乙基己基膦酸-2-乙基己脂(P507)萃取柱色谱分离,EDTA络合滴定混合稀土中单一稀土元素,并应用于多种混合稀土氧化物中单一稀土的全分析。本方法所需设备简单,分析结果准确可靠。

激光热透镜光度分析方法(综述)

激光热透镜效应是1964年Gordon等人首次报道的。他们在研究分子拉曼散射时发现了这一现象,并预言可用于测量溶液中痕量物质的微弱吸收。经过Fang、Swoffod、及Hu等人的努力,使得激光热透镜效应的理论得到了充实和发展,为其在分析领域中的应用打下了基础。1979年Dovichi和Harris首次发表了应用激光热透镜效应进行定量分析,用He-Ne激光为光源建立了单光束实验装置,对Cu-EDTA体系进行了测定。Imasaka等人于1980年采用双光束

[2,4-(CH_3)_2C_5H_5]NdCl_2·3THF-AlEt_3体系引发丁二烯聚合的活性

戊二烯稀土配合物化学目前尚处于萌芽时期,只报道有几个配合物的合成,戊二烯稀土氯化物的合成则至今未见报道.最近,东德专利报道了[2,4-(CH_3)_2C_5-H_5]_3Nd在双烯烃定向聚合上的应用.我们合成了2,4-二甲基戊二烯基稀土二氯化物,并考察了其对双烯烃的聚合催化活性. 1.试剂和分析方法:聚合用溶剂经纯化,活性氧化铝浸泡后使用.稀土含量分析用二甲酚橙为指示剂以EDTA标准溶液滴定;氯含量分析用硫酸铁铵为指示剂,加过量