共查询到20条相似文献,搜索用时 31 毫秒
1.
Rakesh Kumar Mahajan Ravneet Kaur Inderpreet Kaur Vandana Sharma Manoj Kumar 《Analytical sciences》2004,20(5):811-814
A PVC membrane incorporating p-tert-butyl calix[4]crown with imine units as an ionophore was prepared and used in an ion-selective electrode for the determination of mercury(II) ions. An electrode based on this ionophore showed a good potentiometric response for mercury(II) ions over a wide concentration range of 5.0 x 10(-5) - 1.0 x 10(-1) M with a near-Nernstian slope of 27.3 mV per decade. The detection limit of the electrode was 2.24 x 10(-5) M and the electrode worked well in the pH range of 1.3 - 4.0. The electrode showed a short response time of less than 20 s. The electrode also showed better selectivity for mercury(II) ions over many of the alkali (Na+, -1.69; K+, -1.54), alkaline-earth (Ca2+, -3.30; Ba2+, -3.32), and heavy metal ions (Co2+, -3.67; Ni2+, -3.43; Pb2+, -3.31; Fe3+, -1.82). Ag+ ion was found to be the strongest interfering ion. Also, sharp end points were obtained when the sensor was used as an indicator electrode for the potentiometric titration of mercury(II) ions with iodide and dichromate ions. 相似文献
2.
Mohammad Reza Ganjali Farhang Mizani Masoud Salavati-Niasari Mehran Javanbakht 《Analytical sciences》2003,19(2):235-238
A plasticized Cr3+ ion sensor by incorporating 2,3,8,9-tetraphenyl-1,4,7,10-tetraazacyclododeca-1,3,7,9-tetraene (TTCT) ionophore exhibits a good potentiometric response for Cr3+ over a wide concentration range (1.0 x 10(-6)-1.0 x 10(-1) M) with a slope of 19.5 mV per decade. The sensor response is stable for at least three months. Good selectivity for Cr3+ in comparison with alkali, alkaline earth, transition and heavy metal ions, and minimal interference are caused by Li+, Na+, K+, Co2+, Hg2+, Ca2+, Pb2+ and Zn2+ ions, which are known to interfere with other chromium membrane sensors. The TTCT-based electrode shows a fast response time (15 s), and can be used in aqueous solutions of pH 3-5.5. The proposed sensor was used for the potentiometric titration of Cr3+ with EDTA and for a direct potentiometric determination of Cr3+ content in environmental samples. 相似文献
3.
液膜分离富集金与测定微量金 总被引:2,自引:0,他引:2
提出采用乳状液膜体系分离、富集金。该体系包括协同流动载体(TBP和PMBP),表面活性剂(SPAN80),膜的增强剂(液体石蜡),膜溶剂(煤油)和内相(1%质量分数的NaOH水溶液)。实验结果表明,金的迁移率达90.5%以上。此条件下,许多共存金属高于如∑RE3+、Ag2+、Pd2+、Pt4+、Rh3+、Cu2+、Fe3+、Al3+、Pb2+、Zn2+、Mo6+、W6+、Mn2+、Sn4+、Te4+、Se4+、Ca2+和Mg2+等不被迁移,只有金能与这些金属离子得到满意的分离。该法已应用于测定提金溶液和氰化物没出贵金属溶液中的微量金,相对标准偏差为1.3%-3.9%。 相似文献
4.
Javad Zolgharnein Sheida Hosseini Golamhassan Azimi Mohammad Reza Sangi 《Analytical sciences》2003,19(6):871-875
Potassium-decyl-18-crown-6 was used as a highly selective and efficient carrier for uphill transport of silver as AgBr2-complex ion through a chloroform bulk liquid membrane. When thiosulfate anion was used as a metal ion acceptor in the receiving phase the amounts of silver transported across the liquid membrane after 120 and 180 min were 87.0 +/- 1.8% and 96.0 +/- 1.9%, respectively. The selectivity and efficiency of silver transport from aqueous solution containing Cu2+, Zn2+, Ni2+, Cd2+, Pb2+ and Fe3+ ions were investigated. In the presence of EDTA at pH = 4 as suitable masking agent in the source phase, the interfering effects of Pb2+ and Fe3+ ions were diminished drastically. 相似文献
5.
《Journal of membrane science》1986,29(1):37-47
Basic electrochemical properties of an amphoteric ion-exchange membrane (1.0—PA—29), in which almost equal numbers of cationic and anionic sites are distributed homogeneously over the functionalized polymer networks, were studied for a variety of concentration-cell systems. Unlike the usual uniform ion-exchange membrane, potentiometric permselectivities were demonstrated even for ions of the same charge, as shown by the result that distinctive potential responses were observed for a series of alkali metal chloride, sodium salt, and tetra-alkylammonium chloride systems. The sequence of membrane permeabilities to cations and anions calculated from the electrochemical data could well be correlated to the sequence of the hydrated radii of the respective ions. So the potentiometric responses to any electrolyte system can be predicted from the permeability data or hydrated radius values of individual cations and anions. The present results suggest that the homogeneous amphoteric ion-exchange membrane functions effectively as an ion sieve, sifting out the sizes of permeating hydrated cations and anions. 相似文献
6.
The interaction between metal ions and bovine serum albumin (BSA) was studied by using a piezoelectric quartz crystal (PQC) arranged in the electrode-separated configuration. A silanized surface of the PQC was coated with a BSA membrane via a coupling reaction with glutaraldehyde. The frequency shifts obtained from PQC coated with a BSA membrane suggested that various kinds of metal ions could be adsorbed onto the BSA membrane from aqueous solutions containing a low concentration of metal ions (2 or 10 micromol dm(-3)), only when the BSA was denatured with an alkaline solution. Anionic species of Pt(IV) and Au(III) were adsorbed onto the denatured BSA membrane from an acetic acid solution at pH 2.2, and cationic species of Cd(II), Zn(II), Co(II), Ni(II), Cu(II), and Ag(I), and cations, such as Ca2+, Ba2+, and Mg2+, were adsorbed from ammonia buffer at pH 9.5, whereas Al(III), Cr(III), Fe(III), Hg(II), and Pb(II) were hardly adsorbed. The adsorption mechanisms of these metal ions are discussed, based on the electrostatic interaction between the metal ions and the denatured BSA membrane, and complex formation between the metal ions and amino acid residues of the denatured BSA. Further, the PQC coated with a denatured BSA membrane was applied to the determination of Pt and Cd, using large frequency shifts for Pt(IV) and Cd(II). 相似文献
7.
Y Itoh Y Ueda A Hirano M Sugawara K Tohda H Akaiwa Y Umezawa 《Analytical sciences》2001,17(5):621-627
The effect of hydrophobicity of acidic chelating agents as sensing materials on the potentiometric responses of polymeric liquid membranes was investigated. The chelating agents tested were 8-quinolinol (HOx), dithizone (HDz), 1-(2-pyridylazo)-2-naphthol (PAN) and their alkylated analogues, 5-octyloxymethyl-8-quinolinol (HO8Q), di(phexylphenyl)thiocarbazone (C6HDz), 7-pentadecyloxy-1-(2-pyridylazo)-2-naphthol (C15PAN) and a series of N-alkylcarbonyl-N-phenylhydroxylamines (CnPHA, n = 3, 6, 9, 12). The distribution coefficients between membrane solvent and water were determined to evaluate the hydrophobicity of the agents. The potential-pH profiles of the membranes containing hydrophobic chelating agents demonstrated the generation of potentiometric responses, while less hydrophobic agents gave no response. A possible model for the generation of membrane potential is proposed. The charge separation is attained by the permselective uptake of metal cations by the chelating agent anion at membrane/solution interface, where the high hydrophobicity of the agent enables the anionic or deprotonated form of the agents to remain at the membrane/solution interface. 相似文献
8.
Hamid R Zare Masoud Salavati-Niassary Farkhondeh Memarzadeh Mohammad Mazloum Navid Nasirizadeh 《Analytical sciences》2004,20(5):815-819
A novel membrane coated platinum-wire electrode (MCPWE) based on N,N'-bis(2-thienylmethylene)-1,2-diaminobenzene (BTMD) for highly selective determination of Ag+ ion has been developed. The influences of membrane composition and pH on the potentiometric responses of electrode were investigated. The potentiometric responses are independent of the pH of the test solution in the range of 5.0 - 9.0. The electrode shows a linear response for Ag+ ion over the concentration range of 1.0 x 10(-60 to 1.0 x 10(-1) M with a lower detection limit of 6.0 x 10(-7) M. The electrode possesses a Nernstian slope of 59.7 mV decade(-1) and a fast response time of < or = 17 s and can be used for at least 2 months without any observable deviation. The proposed electrode displayed very good selectivity for Ag+ ion with respect to NH4+ and alkali, alkaline earth and some common transition metal ions. The practical utility of the electrode has been demonstrated by its use as the indicator electrode in the potentiometric titration of an AgNO3 solution with a NaI solution and in determination of the silver content of a developed radiological film. 相似文献
9.
A method has been established to study the competing binding of metal ions with protein by a combined technique of microdialysis with high performance liquid chromatography (HPLC). Ni2+, Cd2+, Zn2+, Cu2+ and human serum albumin (HSA) were chosen as model metal ions and protein. The experimental results show that Ni2+ and Cu2+ share a common primary binding site on HSA, and Zn2+ and Cd2+ share a different common primary binding site from them, but there is a common multi-metal binding site for all of those four metal ions. This method show advantages of fast sampling, easily to be operated and especially to be useful when ideal spectroscopic probes are not available for the study of interaction between protein and metal ions. 相似文献
10.
11.
Knobloch B Sigel H Okruszek A Sigel RK 《Chemistry (Weinheim an der Bergstrasse, Germany)》2007,13(6):1804-1814
The interaction between divalent metal ions and nucleic acids is well known, yet knowledge about the strength of binding of labile metal ions at the various sites is very scarce. We have therefore studied the stabilities of complexes formed between the nucleic acid model d(pGpG) and the essential metal ions Mg2+ and Zn2+ as well as with the generally toxic ions Cd2+ and Pb2+ by potentiometric pH titrations; all four ions are of relevance in ribozyme chemistry. A comparison of the present results with earlier data obtained for M(pUpU)- complexes allows the conclusion that phosphate-bound Mg2+ and Cd2+ form macrochelates by interaction with N7, whereas the also phosphate-coordinated Pb2+ forms a 10-membered chelate with the neighboring phosphate diester bridge. Zn2+ forms both types of chelates with formation degrees of about 91% and 2.4% for Zn[d(pGpG)]cl/N7 and Zn[d(pGpG)]-cl/PO, respectively; the open form with Zn2+ bound only to the terminal phosphate group, Zn[d(pGpG)]-op, amounts to about 6.8 %. The various intramolecular equilibria have also been quantified for the other metal ions. Zn2+, Cu2+, and Cd2+ also form macrochelates in the monoprotonated M[H;d(pGpG)] species (the proton being at the terminal phosphate group), that is, the metal ion at N7 interacts to some extent with the P(O)2(OH)- group. Thus, this study demonstrates that the coordinating properties of the various metal ions toward a pGpG unit in a nucleic acid differ: Mg2+, Zn2+, and Cd2+ have a significant tendency to bridge the distance between N7 and the phosphate group of a (d)GMP unit, although to various extents, whereas Pb2+ (and possibly Ca2+) prefer a pure phosphate coordination. 相似文献
12.
The potentiometric titrations of Zn2+, Cu2+ and 12 Ln3+ metal ions were obtained in ethanol to determine the titration constants (defined as the at which the [-OEt]/[Mx+]t ratios are 0.5, 1.5, and 2.5) and in two cases (La3+ and Zn2+) a complete speciation diagram. Several simple monobasic acids and aminium ions were also titrated to test the validity of experimental titration measurements and to establish new constants in this medium that will be useful for the preparation of buffers and standard solutions. The dependence of the titration constants on the concentration and type of metal ion and specific counterion effects is discussed. In selected cases, the titration profiles were analyzed using a commercially available fitting program to obtain information about the species present in solution, including La3+ for which a dimer model is proposed. The fitting provides the microscopic values for deprotonation of one to four metal-bound ethanol molecules. Kinetics for the La3+-catalyzed ethanolysis of paraoxon as a function of are presented and analyzed in terms of La3+ speciation as determined by the analysis of potentiometric titration curves. The stability constants for the formation of Zn2+ and Cu2+ complexes with 1,5,9-triazacyclododecane as determined by potentiometric titration are presented. 相似文献
13.
14.
羧甲基壳聚糖/聚乙烯醇/甘油环氧树脂蛇笼型复合螯合膜的制备及对金属离子的吸附性能 总被引:4,自引:0,他引:4
以交联甘油环氧树脂交联的聚乙烯醇(PVA)为笼树脂,羧甲基壳聚糖(CCTS)为蛇树脂制备了具有蛇笼结构的复合螯合膜,研究了其对Cu^2 、Ni^2 、Pb^2 、Fe^3 、Zn^2 ,Hg”^2 、Cd^2 等金属离子的吸附性能,研究表明,该树脂对Cu^2 、Ni^2 、Pb^2 有较好的吸附性能,其中PVA是对Cu^2 的吸附的主要贡献者,而CCTS则是在对Ni^2 的吸附中起主要作用。该树脂可以用于含Cu^2 废水的处理。 相似文献
15.
A chloroform membrane system containing a given mixture of ketoconazole and oleic acid was applied for the uphill transport of Cd2+ ions as CdI42-. In an HCl medium the ligand could form a stable ion-pair with CdI4(2-), which was readily extractable in the membrane phase. A weak basic solution (pH 8) was used as a suitable stripping medium for the quantitative transport of cadmium across the liquid membrane after 120 min. The selectivity and efficiency of Cd2+ transport from an aqueous solution containing other cations, such as Co2+, Cr3+, Ni2+, Fe2+, Mn2+, Pd2+ and Zn2+ ions, were investigated. It was found that none of these cations interfered with Cd2+ transport. 相似文献
16.
Mercury ion-selective electrodes (ISEs) were prepared with a polymeric membrane based on heterocyclic systems: 2-methylsulfanyl-4-(4-nitro-phenyl)-l-p-tolyl-1H-imidazole (I) and 2,4-diphenyl-l-p-tolyl-1H-imidazole (II) as the ionophores. Several ISEs were conditioned and tested for the selection of common ions. The electrodes based on these ionophores showed a good potentiometric response for Hg2+ ions over a wide concentration range of 5.0 x 10(5-) - 1.0 x 10(-1)M with near-Nernstian slopes. Stable potentiometric signals were obtained within a short time period of 20 s. The detection limits, the working pH range of the electrodes were 1.0 x 10(-5) M and 1.6-4.4 respectively. The electrodes showed better selectivity for Hg2+ ions over many of the alkali, alkaline-earth and heavy metal ions. Also sharp end points were obtained when these sensors were used as indicator electrodes for the potentiometric titration of Hg2+ ions with iodide ions. 相似文献
17.
Ribonucleic acid (RNA) is used as a novel ionophore in plasticized poly(vinyl chloride) matrix membrane sensors for some transition metal ions. Membranes incorporating RNA and doped in Cu(2+), Cd(2+) and Fe(2+) display fast near-Nernstian and stable responses for these ions with cationic slopes of 31.1, 31.3 and 35.5 mV per decade, respectively, over the concentration range 10(-6)-10(-2) M and pH range 4-6.5. The cadmium RNA-based sensor shows no interference by Cu(2+), Fe(2+) Hg(2+) and Ag(+), which are known to interfere significantly with the solid-state CdS/Ag(2)S membrane electrode. The copper RNA-based sensor displays general potentiometric characteristics similar to those based on macrocyclic ionophores and organic ion exchangers and has the advantage of a better selectivity for Cu(2+) over some alkaline earth, divalent and transition metal ions. The iron RNA-based membrane sensor exhibits no interference by Hg(2+) and Zn(2+), which are known to interfere with other previously suggested sensors. The nature and composition of the RNA ionophore and its cadmium complex are examined using electrophoresis, Fourier-transform infrared analysis, elemental analysis and X-ray fluorescence techniques. 相似文献
18.
I Kitagawa K Ohashi H Kawanishi H Shibuya K Shinkai H Akedo 《Chemical & pharmaceutical bulletin》1989,37(6):1679-1681
Oligopeptide lactones (theonellapeptolides) isolated from the Okinawan marine sponge Theonella swinhoei and resin-glycosides (merremosides) from the tuber of an Indonesian medicinal plant Merremia mammosa were examined regarding their activities in transporting Na+, K+, and Ca++ ions into human erythrocytes. Each of these lactones, which had been shown, using a supported liquid membrane, to have an ionophoretic effect on the alkali metal ions, transported the ions to a different extent. The ion transporting activities of these compounds were completely lost when the macrocyclic lactone structures were cleaved by sodium methylate. Resin-glycosides with an additional branched glycosyl residue showed much greater ion transporting activities than those without it. 相似文献
19.
Hong-Seok Kim Dong-Hyun Kim Ki Soo Kim Jun-Hyeak Choi Heung-Jin Choi Sung-Hoon Kim Jun Ho Shim Geun Sig Cha Hakhyun Nam 《Talanta》2007,71(5):1986-1992
The synthesis and potentiometric evaluation of new 1,3,5-tris(thiazolylcarbethoxy)-2,4,6-trimethylbenzene (3), 1,3,5-tris(thiazolylhydroxy)-2,4,6-trimethylbenzene (4), 1,3,5-tris(thiazolylmethyl)-2,4,6-trimethylbenzene (5), and 1,3,5-tris(thiazolylphenyl)-2,4,6-trimethylbenzene (6), toward mono and divalent cations under various pH conditions are outlined. The ion-selective properties of the newly synthesized compounds were studied by measuring the potentiometric responses of the 3-, 4-, 5-, and 6-based membrane electrodes to alkali metal, alkaline earth metal, ammonium, and transition metal ions, under various pH conditions. The 3-based electrode exhibited a Nernstian response to ammonium and potassium under alkaline pH conditions, while the other three electrodes showed a poor potentiometric performance. All electrodes showed substantial responses to silver ion under acidic condition, but there was almost nil response to other transition metal ions (Fe2+, Co2+, Zn2+, Ni2+, Pb2+, Cd2+, Cu2+ and Hg2+). The 3- and 5-based electrodes resulted in near Nernstian responses (51.3 mV and 59.5 mV/pAg+, respectively) with low detection limits (100 ppt), while the 4- and 6-based ones showed sub-Nernstian below 40 mV/pAg+. The results were interpreted with semi-empirically modeled structures. 相似文献
20.
Viktor Csokai Diem Lan Ha Mai Olívia Varga Klára Tóth Miklós Kubinyi Alajos Grün 《Tetrahedron》2008,64(6):1058-1063
Novel fluorogenic 1,3-alt thiacalix[4](N-phenylazacrown-5)ether ionophore has been synthesized by conjugation of the N-phenyl group with borondipyrromethene (BODIPY) fluorophore moiety. The ionophore exhibits pronounced off-on type fluorescent responses to some transition metal ions, in particular to Cu2+. In a PVC membrane electrode, distinct Ag+ selectivity was observed in potentiometric transduction. 相似文献