苯甲醛缩氨基脲铜（II）配合物为载体的高选择性硫氰酸根离子电极的研究

首次研究以苯甲醛缩氨基脲铜（II）[Cu(II)-BASA]为中性载体的PVC膜电极， 该电极对硫氰酸根离子（SCN~-）具有优良的电位响应特性并呈现出反Hofmeister 选择性行为，其选择性次序为：SCN~- > ClO_4~- > I~- > Sal~- > Br~- > NO_3~- > Cl~- > NO_2~- > SO_3~(2-) > SO_4~(2-) > H_2PO_4~-。电极在pH 6. 0的磷酸盐缓冲体系中，对SCN~-在1.0 * 10~(-1)～8.0 * 10~(-6) mol/L浓度范围 内呈近能斯特响应，斜率为56.0 mV/sSCN~- (28 ℃)，检测下限为3.0 * 10~(-6) mol/L。采用交流阻抗技术和紫外可见光谱技术初步研究了阴离子与载体的作用机 理，结果表明配合物中心金属原子的结构以及载体本身的结构与电极的响应行为之 间有非常密切的构效关系。该电极具有响应快、重现性好、检测限低、制备简单等 优点。将电极初步应用于实际样品废水分析，结果与HPLC法一致。     

Bis-dimethylaminobenzaldehyde Schiff-base cobalt(II) complex as a neutral carrier for a highly selective iodide electrode.

A new solvent polymeric membrane electrode based on N,N'-bis-(dimethylaminobenzaldehyde)-glycine cobalt(II) [Co(II)-BDMABG] as a neutral carrier is described, which displays a preferential potentiometric response to iodide ion and an anti-Hofmeister selectivity sequence in the following order: I- > ClO4- > Sal- > SCN- > NO2- > Br- > NO3- > Cl- > SO3(2-) > SO4(2-). The electrode exhibits a near-Nernstian potential linear range of 9.0 x 10(-7)-1.0 x 10(-1) M with a detection limit of 6.8 x 10(-7) M and a slope of -53.0 mV/decade in pH 2.0 of a phosphate buffer solution at 20 degrees C. The response mechanism is discussed in view of the A.C. impedance technique and the UV spectroscopy technique. The electrode was successfully applied to the determination of iodide in Jialing River and Spring in Jinyun Mountains with satisfactory results.     

Highly selective thiocyanate poly(vinyl chloride) membrane electrode based on a cadmium-Schiff's base complex

A PVC membrane electrode based on a cadmium-salen (N,N'-bis-salicylidene-1,2-ethylenediamine) complex as an anion carrier is described. The electrode has an anti-Hofmeister selectivity sequence with a preference for thiocyanate at pH 1.5-11.0. It has a linear response to thiocyanate from 1.0 x 10(-6) to 1.0 x 10(-1) mol L(-1) with a slope of 59.1 +/- 0.2 mV per decade, and a detection limit of 7 x 10(-7) mol L(-1). This electrode has high selectivity for thiocyanate relative to many common organic and inorganic anions. The proposed sensor has a fast response time of approximately 15 s. It was applied to the determination of thiocyanate in a milk sample.     

Highly selective iodide electrode based on the copper(II)-N,N'-bis(salicylidene)-1,2-bis(p-aminophenoxy)ethane tetradentate complex.

In this paper, a new PVC-based liquid-membrane anion-selective electrode based on a copper(II) of N,N'-bis(salicylidene)-1,2-bis(p-aminophenoxy)ethane tetradentate complex (Cu(II)BBAP) is described, which displays a preferential potentiometric response to iodide ion at pH 2.0 and an anti-Hofmeister selectivity sequence: I->SCN->ClO4->NO2->H2PO4->NO3->SO4(2-)>Br->Cl-. The electrode exhibits a near-Nernstian potential linear range of 8.2x10(-7)-1.0x10(-1) M with a detection limit of 5.3x10(-7) M and a slope of -58.8 mV per decade. The A.C. impedance technique and the UV/Vis spectroscopy technique were used to analyze the response mechanism. The electrode could be applied to determine iodide in medicine analysis, and the obtained results were fairly satisfactory.     

Binuclear Schiff base complex of manganese(III) as a neutral carrier for a highly selective iodide electrode.

A new highly selective iodide electrode incorporating a binuclear manganese(III) complex, bis(salicylaldehyde-aminopropanol)dichloroaceticdimanganese(III) [Mn(III)(2)-BSAPDCA], as a neutral carrier is described. The electrode displays an anti-Hofmeister selectivity sequence: iodide > perchlorate > salicylate > thiocyanate > nitrate > bromide > nitrite > chloride > sulfate. The excellent selectivity for iodide is related to a direct interaction between the central Mn(III) atom and iodide and a steric effect associated with the structure of the carrier, which is supported by UV spectroscopy and AC impedance techniques. The electrode exhibits a near-Nernstian potentiometric linear response range to iodide from 1.0 x 10(-1) to 2.0 x 10(-5) mol/L with a detection limit of 8.0 x 10(-6) mol/L and a slope of -60.3 mV/decade in pH 3.0 of phosphate buffer solutions at 20 degrees C. From a comparison of the potentiometric response characteristics between a binuclear manganese(III) complex, Mn(III)(2)-BSAPDCA, and a mononuclear manganese(III) complex, Mn(III)-BSAPB, an enhanced response towards iodide from a binuclear metallic complex-based electrode was observed. The electrode, based on binuclear manganese(III) complex, was successfully applied to the determination of inorganic total iodine in iodized table salt with satisfactory results.     

双安息香缩三乙四胺双核钴硫氰酸根的离子电极研究

季铵盐型阴离子选择性电极由于其电位选择性往往表现出Hofmeister顺序,故使其应用受到限制,因此,研究呈现反Hofmeister行为的阴离子选择性电极已成为离子电极研究领域中重要的研究方向之一。近年来,人们研制出了以金属配合物为中性载体且呈现反Hofmeister行为的阴离子选择电极,本实验室也分别研究了以Schiff碱金属配合物及二氮杂四烯基金属配合物为载体的碘离子和水杨酸根离子电极,但上述电极多数是以单核金属配合物为载体,以双核金属配合物作为载体的电极则很少。     

Salicylate ion-selective electrode based on new tetranuclear copper complexes of O-vannlin-methionine as neutral carriers.

A new salicylate-selective PVC membrane electrode based on a new Schiff base tetranuclear copper complex of O-vannlin-methionine (Cu(II)(4)-TVM) as a neutral carrier is described. This electrode displays a preferential potentiometric response to salicylate and an anti-Hofmeister selectivity sequence in the following order: Sal(-) > ClO(4)(-) > SCN(-) > I(-) > NO(2)(-) > NO(3)(-) > Br(-) > Cl(-) > SO(3)(2-) > SO(4)(2-) > H(2)PO(4)(-). The electrode exhibits near-Nernstian potential linear range of 1.5 x 10(-6)-1.0 x 10(-1) M with a detection limit of 8.0 x 10(-7) M and a slope of -56.3 mV/decade in pH 3.0-8.0 of phosphorate buffer solution at 20 degrees C. Thanks to the tetranuclear copper(II) in the carrier, the electrode has the advantages of simplicity, fast response, fair stability and reproducibility and low detection limit. The response mechanism to the electrodes is discussed by the a.c. impedance technique and the UV spectroscopy technique. The electrode can be applied to analyses of medicine and the results obtained are in fair agreement with the results given by a standard method.     

A new lead(II)-selective PVC-coated graphite rod electrode based on a Schiff base complex.

A new lead(II)-selective electrode has been developed based on bis(acetylacetone)-p-phenylenediamine-lead(II) [LPb(NO3)2]H2O complex ionophore as a sensing material, dioctylphthalate (DOP) as a solvent mediator and PVC as a matrix. This electrode exhibits a linear Nernstian response over the concentration range of 1 x 10(-5)-1 x 10(-1) mol l(-1) of Pb(II) cation, with a cationic calibration slope of 30.0 +/- 0.2 mV/concentration decade and a detection limit of 2 x 10(-6) mol l(-1) (0.40 ppm). It has a fast response time and can be used for a period of 2 months without any divergence in potentials. The proposed electrode reveals a good selectivity for Pb(II) over a wide variety of other tested cations and could be used in the pH range of 4-8. It was successfully used for direct determination of Pb(II) concentration in some samples. The obtained results show a good agreement with those obtained by an atomic absorption spectrometric method. The average recovery obtained is 96.5 +/- 0.5% with standard deviation of 1.2% (n = 8).     

Potentiometric membrane electrode for salicylate based on an organotin complex with a salicylal Schiff base of amino acid.

A novel salicylate-selective electrode based on an organotin complex with a salicylal Schiff base of amino acid salicylaldehydeaminoacid-di-n-butyl-Sn(IV) [Sn(IV)-SAADB] as ionophore is described, which exhibits high selectivity for salicylate over many other common anions with an anti-Hofmeister selectivity sequence: Sal- > PhCOO- > SCN- > Cl04- > I- > NO3- > NO2- > Br- > Cl- > CH3COO-. The electrode, based on Sn(IV)-SAADB, with a 30.44 wt% PVC, a 65.45 wt% plasticizer (dioctyl phthalate, DOP), a 3.81 wt% ionophore and a 0.3 wt% anionic additive is linear in 6.0 x 10(-6) - 1.0 x 10(-1) mol l(-1) with a detection limit of 2.0 x 10(-6) mol l(-1) and a slope of 62.0 +/- 1.2 mV/decade of salicylate concentration in a phosphate buffer solution of pH 5.5 at 25 degrees C. The influence on the electrode performances by lipophilic charged additives was studied, and the possible response mechanism was investigated by UV spectra. The electrode was applied to medicine analysis and the result obtained has been satisfactory.     

Thiocyanate ion-selective PVC membrane electrode based on N,N'-ethylene-bis(4-methylsalicylidineiminato)nickel(II).

A highly selective poly(vinyl chloride) (PVC) membrane electrode based on an N,N'-ethylene-bis(4-methyl-salicylidineiminato) nickel(II) [Ni(EBMSI)] complex as a carrier for a thiocyanate-selective electrode is reported. The influences of the membrane composition, pH and possible interfering anions were investigated based on the response properties of the electrode. The electrode exhibited a good Nernstian slope of -58.9 +/- 0.7 mV decade(-1), over a wide pH range of 3.5 - 8.5 and a linear range of 1.0 x 10(-6) - 1.0 x 10(-1) M for thiocyanate. The detection limit of electrode was 3.1 x 10(-7) M SCN(-). The selectivity coefficients determined by a fixed interference method (FIM) indicate that a good discriminating ability towards the SCN- ion compared to other anions. The proposed sensor had a fast response time of about 5 - 15 s and could be used for at least 3 months without any considerable divergence in the potential. It was applied as an indicator electrode in the titration of thiocyanate with Ag+ and in the potentiometric determination of thiocyanate in saliva and urine samples.     

Comparative electrochemical study of new self-assembled monolayers of 2-{[(Z)-1-(3-furyl)methylidene]amino}-1-benzenethiol and 2-{[(2-sulfanylphenyl)imino]methyl}phenol for determination of dopamine in the presence of high concentration of ascorbic acid and uric acid

The comparative electrochemical behavior of self-assembled monolayers of two Schiff's bases, 2-{[(Z)-1-(3-furyl)methylidene]amino}-1-benzenethiol (FMAB) and 2-{[(2-sulfanylphenyl)imino]methyl}phenol (SIMP) on a bare gold electrode (Au FMAB SAM-modified electrode and Au SIMP SAM-modified electrode, respectively), was investigated by means of cyclic voltammetry and electrochemical impedance spectroscopy in a 0.1 mol L(-1) KCl solution that contains 5.0 × 10(-3) mol L(-1) [Fe(CN)(6)](3-/4-). The results revealed that the modified electrodes showed an electrocatalytic activity toward the anodic oxidation of dopamine by a marked enhancement in the current response and lower overpotential (60 and 90 mV for the Au FMAB and Au SIMP SAM-modified electrodes, respectively) in phosphate buffer solution at pH 6.0. The Au SIMP SAM-modified electrode was applied successfully to the determination of dopamine in the presence of a high concentration of ascorbic acid. Selective detection was realized in total elimination of ascorbic acid response-a method different from the ones based on the potential separations. The detection limit of dopamine was 5.0 × 10(-8) mol L(-1) in a linear range from 1.0 × 10(-6) to 1.2 × 10(-4) mol L(-1) in the presence of 1.0 × 10(-3) mol L(-1) ascorbic acid. The interference studies also showed that the Au SIMP SAM-modified electrode exhibited good selectivity in the presence of a large excess of uric acid and could be employed for the determination of dopamine in pharmaceutical formulations, plasma samples and human urine with adequate selectivity and precision.     

Highly selective PVC-membrane electrodes based on Co(II)-Salen for determination of nitrite ion.

A cobalt(II) derivative was used as a suitable ionophore for the preparation of a polymeric membrane nitrite-selective electrode. The electrode reveals a Nemstian behavior over a very wide NO2- ion concentration range (1.0 x 10(-6)-1.0 x 10(-1) M) and a very low detection limit (5.0 x 10(-7) M). The potentiometric response is independent of the pH of solution in the pH range 4.0-9.5. The electrode shows advantages such as low resistance, fast response and, most importantly, good selectivity relative to a wide variety of inorganic and organic anions. In fact, the selectivity behavior of the proposed NO2- ion-selective electrode shows great improvements compared to the previously reported electrodes for nitrite ion. The proposed electrodes could be used for at least 2 months without any significant changes in potentials. The electrode was successfully applied to the determination of nitrate ion concentrations in sausage and milk samples.     

Determination of SCN- in urine and saliva of smokers and non-smokers by SCN(-)-selective polymeric membrane containing a nickel(II)-azamacrocycle complex coated on a graphite electrode.

The construction, performance characteristics, and application of a novel polymeric membrane coated on a graphite electrode with unique selectivity towards SCN- are reported. The electrode was prepared by incorporating Ni(II)-2,2,4,9,9,11-hexamethyltetraazacyclotetradecanediene perchlorate into a plasticized poly(vinyl chloride) membrane. The influences of membrane composition, pH and foreign ions were investigated. The electrode displays a near Nernstian slope (-57.8 mV decade-1) over a wide concentration range of 1 x 10(-7)-1 x 10(-1) M of SCN- ion. The electrode has a detection limit of 4.8 x 10(-8) M (2.8 ng/cm3) SCN- and shows response times of about 15 s and 120 s for low to high and high to low concentration sequences, respectively. The proposed sensor shows high selectivity towards SCN- over several common organic and inorganic anions. The electrode revealed a great enhancement in selectivity coefficients and detection limit for SCN-, in comparison with the previously reported electrodes. It was successfully applied to the direct determination of SCN- in milk and biological samples, and as an indicator electrode in titration of Ag+ ions with thiocyanate.     

钴(II)-丁二酮肟-亚硝酸盐体系极谱催化波的机理研究

在氨性底液(PH8)中, 钴(II)-丁二酮肟(DMG)-亚硝酸盐体系产生高灵敏的极谱催化波. 利用吸附伏安法, 测定下限可达1×10^-^1^1mol.dm^-^3Co. 我们用多种电化学方法和紫外可见分光光度法证明, 吸附在汞电极表面的[NH4]2[Co(DMG)2(NO2)2]是有很高电活性的混配化合物, 在复杂的电还原过程中, 不仅Co(II)和DMG被催化还原, 而且NO2^-也被催化还原, 从而产生很大的催化电流, 本文再一次证明, “活性钴"在催化波的形成过程中起着重要的作用.     

Study of a bis-furaldehyde Schiff base copper(II) complex as carrier for preparation of highly selective thiocyanate electrodes

A new highly selective thiocyanate electrode based on N,N-bis-(furaldehyde)-1,2-phenylenediamine-dipicolyl copper(II) complex [Cu(II)-BFPD] as neutral carrier is described. The electrode has an anti-Hofmeister selectivity sequence: SCN^–>I^–>Sal^–>ClO₄ ^–>Br^–>NO₂ ^–>Cl^–>NO₃ ^–>SO₄ ^2–>SO₃ ^2–>H₂PO₄ ^– and a near-Nernstian potential linear range for thiocyanate from 1.0×10^–1 to 5.0×10^–6 mol L^–1 with a detection limit 2.0×10^–6 mol L^–1 and a slope of 57.5 mV decade^–1 in pH 5.0 of phosphate buffer solution at 20 °C. The response mechanism is discussed on the basis of results from A.C. impedance measurement and UV spectroscopy. The anti-Hofmeister behavior of the electrode results from a direct interaction between the central metal and the analyte ion and a steric effect associated with the structure of the carrier. The electrode has the advantages of simplicity, fast response, fair stability and reproducibility, and low detection limit. The selectivity of electrodes based on [Cu(II)-BFPD] exceeds that of classical anion-sensitive membrane electrodes based on ion exchangers such as lipophilic quaternary ammonium or phosphonium salts. Application of the electrode for determination of thiocyanate in waste water samples from a laboratory and a gas factory, and in human urine samples, is reported. The results obtained were fair agreement with the results obtained by HPLC.     

牛磺酸双核铜络合物为载体的高选择性硫氰酸根离子电极的研究

本文报道了一种以牛磺酸双核铜络合物为中性载体的硫氰酸根PVC膜电极。该电极对硫氰酸根有良好的电位响应并呈现出anti-Hofmeister行为,其选择性顺序SCN^->I^->ClO₄^->Sal^->NO₃^-> NO₂^-> Br^- > Cl^- > SO₃^-> SO₄ ^2-。在20℃ pH 5.0的磷酸缓冲溶液中,其线性范围为1.0´10 ^-1~ 1.0´10^-6mol×L-1,检测线为8.0×10 ^-7mol•L^-1,斜率为 -56.5 mV/pcSCN^-。紫外、红外和交流阻抗研究表明电极的高选择性与载体的立体结构和分析物与中心金属离子的作用相关。将该电极用于废水和人体尿液中硫氰酸根的测定,获得了较满意的结果。     

Voltammetric determination of cadmium(II) using a chemically modified electrode

An 1-(pyridylazo)-2-naphthol modified glassy carbon electrode has been investigated as sensor for the measurement of trace levels of Cd2+. Cd2+ is deposited on the surface of a PAN modified glassy carbon electrode at -1.10 V (vs. SCE) via forming Cd2+-PAN and subsequent reduction at the electrode. In the following step, Cd-PAN is oxidized, and voltammograms are recorded by scanning the potential in a positive direction. Calibration plots were found to be linear in the range 2 x 10(-8) mol/L to 8 x 10(-7) mol/L. The detection limit was 5 x 10(-10) mol/L, and the coefficient of variation, determined on one single electrode at a concentration of 5 x 10(-7) mol/L, was calculated to be 3.2% (n = 5). Using this new kind of modified electrode, trace levels of Cd(II) in water samples were determined; the average recovery was calculated to be 98.78%.     

Nitric oxide biosensors based on Hb/phosphatidylcholine films.

Hemoglobin (Hb) was entrapped in a phosphatidylcholine (PC) film and immobilized at a pyrolytic graphite (PG) electrode surface. Its electron-transfer reactivity and enzyme activity were characterized by employing electrochemical methods. It was observed that Hb exhibited direct electrochemistry as well as enzyme-like activity towards the electrocatalytic reduction of NO in PC film. An unmediated, reagentless nitrogen oxide (NO) biosensor was accordingly prepared. Experimental results revealed that the peak current related to NO was linearly proportional to its concentration in the range of 1.0 x 10(-7)-3.0 x 10(-4) mol/L. The detection limit was estimated to be 1.0 x 10(-7) mol/L. Considering its good stability, nice selectivity and easy construction, this biosensor shows great promise for the rapid determination of traces of NO.     

长寿命高选择性液膜碘离子电极的研究

合成了PVC-双硫腙-Hg(Ⅱ)载体.以该载体物质制备了高选择性碘离子电极,其选择性次序为:I^-》ClO₄^->SCN^->NO₂^-》Sal^-～Br^->NO₃^->Cl^-.电极对碘离子的线性响应范围为1×10^-3～5×10^-7mol/L,检测下限为2×10^-7mol/L,斜率为(59±1)mV/decade(16℃).并研究了电极的响应机理,表明系碘离子与载体中金属汞原子直接作用.将该电极应用于食盐中碘的测定,取得了满意的结果.     

直接电位法测定工业废水中的硫氰酸根离子

用直接电位法测定了统扑净生产废水和印染厂排放废水中硫氰酸根的浓度。在温度为 1 6℃ ,浓度为 0 .0 2 mol/L HCl的体系中 ,以功能高分子 PVC-双硫腙 -铜 ( I)载体的 SCN-离子电极在 SCN-离子浓度为 1 .0× 1 0 -2 ～ 5× 1 0 -6mol/L时呈能斯特响应 ,斜率为 58± 2 m V/dec,检出限为 2 .0× 1 0 -6mol/L。电极的选择性次序为 :SCN->>Cl O4 -～Sal->>Cl->NO3 ->HPO4 2 ->SO4 2