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1.
报道了在适量十六烷基三甲基溴化铵 (CTMAB)存在下 ,高灵敏度测定水体中铅、银离子的化学修饰碳糊电极。在pH 2 .5 0 .1mol LKNO3溶液中 ,铅、银离子在钠型蒙脱石修饰碳糊电极上通过离子交换而富集 ,同时被还原。在阳极扫描过程中 ,分别在 - 0 .5 2V和 0 .2 3V(vs.SCE)处出现灵敏的溶出峰。详细研究了测定水样中铅、银离子的条件 ,如介质的pH、CTMAB用量、修饰剂用量、富集电位和时间等。该修饰电极连续测定铅、银离子的线性范围为 5 .0× 10 - 9mol L~ 1.0× 10 - 7mol L(Pb2 + )和 8.0× 10 - 9mol L~ 1.0× 10 - 7mol L(Ag+ ) ,富集 4min后检出限分别为 1.0× 10 - 1 0 mol L(Pb2 + )和 3.0× 10 - 1 0 (Ag+ )。  相似文献   

2.
槲皮素修饰碳糊电极吸附溶出伏安法测定人血清中铜   总被引:4,自引:0,他引:4  
制作了用槲皮素作修饰剂的修饰碳糊电极 ,利用此电极为工作电极 ,建立了测定痕量铜的新方法。在甲酸钠 -盐酸缓冲溶液 ( p H4.7)中 ,于 0 .2 0 V( vs.SCE下同 )处搅拌富集 ,铜 ( )与碳糊修饰电极表面的槲皮素形成电活性络合物而吸附富集于电极表面 ,于 - 0 .40 V静止还原后 ,阳极化线性扫描 ,在 - 0 .0 3V左右获得一灵敏的二次导数溶出峰。在不同富集时间下 ,其二次导数峰电流与铜 ( )浓度分别在1 .5× 1 0 - 9~ 8.0× 1 0 - 8mol/ L和 1 .5× 1 0 - 8~ 9.0× 1 0 - 7mol/ L两个范围内成良好的线性关系 ,检出限可达 8.0× 1 0 - 10 mol/ L。同时探讨了电极反应机理。方法应用于人血清中痕量铜的测定 ,获得了令人满意的结果  相似文献   

3.
双硫腙修饰玻碳电极阳极溶出伏安法测定痕量镉和铅   总被引:24,自引:0,他引:24  
黄文胜  杨春海  张升辉 《分析化学》2002,30(11):1367-1370
报道了双硫腙修饰玻碳电极同时测定痕量镉和铅的电分析方法。镉和铅离子通过与电极表面的双硫腙发生螯合作用而富集在电极表面 ,同时在 -1 .2 0V(vs.SCE)还原成零价镉和铅 ,当电极电势从 -1 .2 0V向 -0 .3 0V扫描时 ,被还原的镉和铅从电极表面溶出 ,分别于 -0 .78V和 -0 .4 8V左右形成灵敏的阳极溶出峰。优化了支持电解质及pH值、双硫腙用量、富集电位及时间等实验参数。利用该修饰电极测定镉、铅的线性范围分别为 1 .0×1 0 - 8~ 2 .5× 1 0 - 6 mol L和 5 .0× 1 0 - 9~ 2 .5× 1 0 - 6 mol L。检测限分别为 5 .0× 1 0 - 9mol L和7.0× 1 0 - 1 0 mol L。该法用于实际水样中镉和铅的测定 ,平均回收率分别为 99.3 0 %和 99.5 4 %。  相似文献   

4.
茜素修饰碳糊电极吸附伏安法测定痕量铜   总被引:3,自引:0,他引:3  
报道了采用茜素修饰碳糊电极测定痕量铜的阳极溶出伏安法。在浓度为0 .1 mol/L 的 HAc- Na Ac缓冲溶液 (p H4.5)中 ,于 +0 .1 0 V处富集 ,- 0 .30 V还原后再进行阳极化扫描 ,于 - 0 .0 5V处获得一灵敏的铜的溶出峰 ,二次导数峰电流与铜浓度在 1 .6× 1 0 -9mol/L~ 4.7× 1 0 -7mol/L范围内呈线性关系 ,检出限达 8.0× 1 0 -10 mol/L。同时 ,对电极反应机理进行了讨论。方法应用于锌合金中铜的测定。  相似文献   

5.
研制了邻苯三酚红 ( PR)修饰碳糊电极 ,研究了采用该电极测定痕量锡的阳极溶出伏安法。在 0 .1 5 mol/L乙酸盐缓冲溶液 ( p H 4.5 )中 ,通过开路富集 ,Sn( )与修饰电极表面的邻苯三酚红生成络合物而富集于电极表面 ,然后介质交换至 4.0mol/L盐酸中 ,于 - 0 .80 V还原后再进行阳极化扫描 ,于 - 0 .69V左右获得一灵敏的 Sn的溶出峰 ,二次导数峰电流与 Sn( )浓度在 1 .68× 1 0 - 8~ 1 .68× 1 0 - 6mol/L范围内呈现良好的线性关系 ,检出限达 8× 1 0 - 9mol/L。对电极反应机理进行了讨论 ,方法已应用于罐头食品中锡的测定  相似文献   

6.
茜素紫修饰碳糊电极阳极溶出伏安法测定痕量锡   总被引:9,自引:0,他引:9  
研究了利用茜素紫修饰碳糊电极测定痕量锡的阳极溶出伏安法。在 0 1 5mol/L醋酸盐缓冲溶液 (pH 4 .8)中 ,通过开路富集 ,Sn 和茜素紫形成络合物富集于电极表面 ,然后经过介质交换至 3 0mol/L的盐酸溶液中 ,于 -0 .80V还原后再进行阳极化扫描 ,于 -0 .68V左右获得一灵敏的锡的溶出峰。二次导数峰电流与Sn 浓度在 8.4× 1 0 -9~ 1 .4× 1 0 -6mol/L范围内呈良好的线性关系。检出限达 4×1 0 -9mol/L ,同时对电极反应机理进行了讨论。  相似文献   

7.
研究了芦荟大黄素在以 0 .1mol/LHAc (pH 2 .89)为支持电解质 ,玻碳电极为工作电极的吸附伏安行为 .结果表明芦荟大黄素存在一个准可逆的双电子转移过程 ,其峰电流Ip 和峰电位Ep 与溶液 pH值有关 .同时还建立了用 1.5阶微分阳极溶出伏安法测定含量的新方法 .在 - 0 .80V(vs.SCE)电位下富集 ,可得一灵敏的微分阳极溶出峰 ,峰电位Ep 为 - 0 .38V ,峰电流Ip 与芦荟大黄素的浓度在 2 .0× 10 - 7~ 8.0× 10 - 6 mol/L范围内成线性关系 ,最低检出限为 1.0× 10 - 7mol/L .该法用于含有芦荟大黄素体系的测定 ,具有简便、快速、准确等优点  相似文献   

8.
报道EDTA/碳糊修饰电极的制备及对银离子的测定。该电极在硝酸介质中 - 0 .6 0V(vs .Ag/AgCl)电位下富集Ag+ ,在 +0 .0 8V处得到一个灵敏的阳极溶出峰 ,峰电流与Ag+ 浓度在 1.0× 10 -9~ 1.0× 10 -6mol/L范围呈良好线性关系 ,检出限为 6 .8× 10 -10 mol/L。  相似文献   

9.
制作了用桑色素作修饰剂的碳糊修饰电极 ,利用该电极为工作电极 ,建立了测定痕量铅的新方法。在甲酸钠 盐酸缓冲溶液 (pH 4 .9)中 ,在 - 0 .10V(vs .SCE)下搅拌富集 ,铅 (Ⅱ )与化学修饰碳糊电极表面的桑色素形成电活性络合物而吸附富集于电极表面 ,经 - 0 .85V(vs.SCE)静止还原后 ,阳极化线性扫描 ,在 - 0 .4 3V(vs .SCE)获得一灵敏的二次导数溶出峰。在最佳条件下分别富集 360s和 180s ,其二次导数峰电流与铅 (Ⅱ )浓度分别在 5 .0× 10 - 9~ 1.0× 10 - 7mol·L- 1和 2 0×10 - 8~ 1.0× 10 - 6 mol·L- 1两个范围内呈良好的线性关系 ,富集 6min ,检出限可达 1.0× 10 - 9mol·L- 1(S/N =3)。同时 ,探讨了电极反应机理。方法应用于尿铅测定 ,获得满意的结果  相似文献   

10.
Nafion修饰玻碳电极吸附伏安法直接测定邻氨基苯酚   总被引:5,自引:0,他引:5  
在 p H=2 .0的 0 .1 mol/ L H3 PO4 缓冲溶液中 ,开路搅拌富集 2 min后 ,从 0 .0 0~ +1 .0 0 V阳极扫描 ,OAP在 Nafion修饰玻碳电极上出现一灵敏的氧化峰 ,峰电位位于 0 .44 V。该峰电流与 OAP在 1× 1 0 - 7~ 2 .5× 1 0 - 5mol/ L的浓度范围内有良好的线性关系 ,检出限为 1× 1 0 - 8mol/ L。对支持电解质的种类及 p H值、Nafion的用量、富集电位及时间、以及扫描速度等进行了优化 ,提出了一种直接测定邻氨基苯酚的电化学方法。将此方法用于水样中邻氨基苯酚的测定 ,取得了满意的结果  相似文献   

11.
In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.  相似文献   

12.
KMnO4-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.  相似文献   

13.
The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.  相似文献   

14.
Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.  相似文献   

15.
A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.  相似文献   

16.
The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp3)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp2)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp2)?H and aliphatic 1,5- and 1,6-C(sp3)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp3)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp2)?H insertion.  相似文献   

17.
The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.  相似文献   

18.
An efficient approach to the synthesis of highly congested di, penta and hexacyclic pyrazoles as well as imidazole fragment containing novel heterocyclic molecule has been developed through a carbanion induced transformation of suitably functionalized 2H-pyran-2-ones, benzo[h]chromene and thiochromeno[4,3-b]pyrans. Due to the presence of fluorescence, we report their prime application metal sensor as off/on switching in ferric ions.  相似文献   

19.
N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).  相似文献   

20.
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