共查询到20条相似文献,搜索用时 31 毫秒
1.
《Electroanalysis》2006,18(21):2070-2078
A highly selective potentiometric sensor for thiocyanate ion based on the use of a newly synthesized organo‐palladium ion exchanger complex dispersed in a plasticized poly(vinyl chloride) membrane is described. The sensor displays a Nernstian response (?57.8±0.2 mV decade?1) over a wide linear concentration range of thiocyanate (1.0×10?6–1.0×10?1 mol L?1 ), low detection limit (6.3×10?7 mol L?1), fast response (20 s), stable potential readings (±0.4 mV), good reproducibility (±0.9%), long term stability (8 weeks), high precision (±0.7%) and applicability over a wide pH range (4–10). Negligible interferences are caused by F?, Cl?, I?, Br?, NO3?, NO2?, CN?, SO42?, S2O32?, PO43?, citrate, acetate and oxalate ions. Under hydrodynamic mode of operation (FIA), the calibration slope is ?51.1±0.1 mV decade?1, the linear response range is 1.0×10?5–1.0×10?1 mol L?1 SCN? and the sample throughput is 40–45 per hour. The sensor is satisfactory used for manual and flow injection potentiometric determination of SCN? in the saliva and urine of cigarette smokers and non smokers. The data agree fairly well with results obtained by the standard spectrophotometric technique. Direct potentiometry and potentiometric titration of SCN? with Ag+ are also monitored with the sensor. 相似文献
2.
A potentiometric sensor for lead(II) ions based on the use of 1,4,8,11‐tetrathiacyclotetradecane (TTCTD) as a neutral ionophore and potassium tetrakis‐(p‐chlorophenyl)borate as a lipophilic additive in plasticized PVC membranes is developed. The sensor exhibits linear potentiometric response towards lead(II) ions over the concentration range of 1.0×10?5–1.0×10?2 mol L?1 with a Nernstian slope of 29.9 mV decade?1 and a lower limit of detection of 2.2×10?6 mol L?1 Pb(II) ions over the pH range of 3–6.5. Sensor membrane without a lipophilic additive displays poor response. The sensor shows high selectivity for Pb(II) over a wide variety of alkali, alkaline earth and transition metal ions. The sensor shows long life span, high reproducibility, fast response and long term stability. Validation of the method by measuring the lower limit of detection, lower limit of linear range, accuracy, precision and sensitivity reveals good performance characteristics of the proposed sensor. The developed sensor is successfully applied to direct determination of lead(II) in real samples. The sensor is also used as an indicator electrode for the potentiometric titration of Pb(II) with EDTA and potassium chromate. The results obtained agree fairly well with data obtained by AAS. 相似文献
3.
《中国化学快报》2021,32(9):2833-2836
We report the fabrication of highly ordered Nb2O5 nanochannel film (Nb2O5-NCF) onto niobium foil by an anodization method. After thermal treatment, the obtained Nb2O5-NCF with rich oxygen vacancies exhibits electrochemical N2 reduction reaction (NRR) activity with an NH3 yield rate of 2.52 × 10−10 mol cm-2 s-1 and a faradaic efficiency of 9.81% at −0.4 V (vs. RHE) in 0.1 mol/L Na2SO4 electrolyte (pH 3.2). During electrocatalytic NRR, the Nb2O5-NCF takes place electrochromism (EC), along with a crystalline phase transformation from pseudo hexagonal phase to hexagonal phase owing to H+ insertion. This results in the reduced NRR activity due to the decrease of oxygen vacancies of hexagonal phase Nb2O5, which can be readily regenerated by low-temperature thermal treatment or applying an anodic potential, showing superior recycling reproducibility. 相似文献
4.
《Electroanalysis》2017,29(12):2793-2802
In this work, SiO2/Nb2O5/ZnO prepared by the sol‐gel processing method was used as substrate base for immobilization of the protoporphyrin‐IX ion. Iron(III) ion was inserted into the porphyrin ring (SiNbZn‐PPFe). A simple square wave voltammetry method based on a composite sensor carbon paste electrode of this material,designed as EPC‐SiNbZn‐PPFe, was developed and validated successfully for the determination of L‐tryptophan (Trp). The optimum conditions were obtained by using sensor modified with 18.00 mg SiNbZn‐PPFe material, 12.00 mg graphite powder and 6.0 μL mineral oil and phosphate buffer 0.3 mol L−1 pH 7.0. The sensitivity of the sensor was found to be 0.523 AL mol −1, linear range from 10 to 70 μmol L−1 and limit of detection of 3.28 μmol L−1. Therefore, the developed method was successfully applied for the Trp determination in real samples of pharmaceutical formulation and can be used for routine quality control pharmaceutical formulations containing Trp. 相似文献
5.
Ashok K. Singh A.K. Jain Jitendra Singh Sameena Mehtab 《International journal of environmental analytical chemistry》2013,93(15):1081-1098
Plasticised membranes using 2-[{(2-hydroxyphenyl)imino}methyl]-phenol (L1) and 2-[{(3-hydroxyphenyl)imino}methyl]-phenol (L2), have been prepared and investigated as Cu2+ ion-selective sensors. Effect of various plasticisers, namely, dibutyl phthalate (DBP), dibutyl sebacate (DBS), benzyl acetate (BA), o-nitrophenyloctylether (o-NPOE) and anion excluders, oleic acid (OA) and sodium tetraphenylborate (NaTPB) was studied and improved performance was observed in several instances. Optimum performance was observed with membranes of (L1) having composition L1 : DBS : OA : PVC in the ratio of 6 : 54 : 10 : 30 (w/w, %). The sensor works satisfactorily in the concentration range 3.2 × 10?8–1.0 × 10?1 mol L?1 with a Nernstian slope of 29.5 ± 0.5 mV decade?1 of a cu2+ . The detection limit of the proposed sensor is 2.0 × 10?8 mol L?1 (1.27 ng mL?1). Wide pH range (3.0–8.5), fast response time (7 s), sufficient (up to 25% v/v) non-aqueous tolerance and adequate shelf life (3 months) indicate the utility of the proposed sensor. The potentiometric selectivity coefficients as determined by matched potential method indicate selective response for Cu2+ ions over various interfering ions, and therefore could be successfully used for the determination of copper in edible oils, tomato plant material and river water. 相似文献
6.
An amperometric dipyrone sensor based on a polymeric nickel-salen (salen = N,N´-ethylenebis(salicydeneiminato)) film coated platinum electrode was developed. The sensor was constructed by electropolymerization of nickel-salen complex at a platinum electrode in acetonitrile/tetrabuthylamonium perchlorate by cyclic voltammetry. After cycling the modified electrode in a 0.50 mol L-1 KCl solution, the estimated surface concentration was found to be equal to 1.29 x 10-9 mol cm-2. This is a typical behavior of an electrode surface immobilized with a redox couple that can usually be considered as a reversible single-electron reduction/oxidation of the nickel(II)/nickel(III) couple. A plot of the anodic current versus the dipyrone concentration for chronoamperometry (potential fixed = +0.50 V) at the sensor was linear in the 4.7 x 10-6 to 1.1 x 10-4 mol L-1 concentration range and the concentration limit was 1.2 x 10-6 mol L-1. The proposed electrode is useful for the quality control and routine analysis of dipyrone in pharmaceutical formulations. 相似文献
7.
《Electroanalysis》2004,16(8):633-639
A potentiometric sensor constructed from a mixture of 25% (m/m) spinel‐type manganese oxide (lambda‐MnO2), 50% (m/m) graphite powder and 25% (m/m) mineral oil is used for the determination of lithium ions in a flow injection analysis system. Experimental parameters, such as pH of the carrier solution, flow rate, injection sample volume, and selectivity for Li+ against other alkali and alkaline‐earth ions and the response time of this sensor were investigated. The sensor response to lithium ions was linear in the concentration range 8.6×10?5–1.0×10?2 mol L?1 with a slope 78.9±0.3 mV dec?1 over a wide pH range 7–10 (Tris buffer), without interference of other alkali and alkaline‐earth metals. For a flow rate of 5.0 mL min?1 and a injection sample volume of 408.6 μL, the relative standard deviation for repeated injections of a 5.0×10?4 mol L?1 lithium ions was 0.3%. 相似文献
8.
Dimethyl-4,4-dimethoxy-5,6,5′,6′-dimethylene dioxy biphenyl-2,2-dicarboxylate (DDB) liver drug is used as a novel ionophore in plasticized poly (vinyl chloride) (PVC) matrix membrane sensors for barium ions. Optimum performance characteristics are displayed by membrane sensor incorporating DDB ionophore, potassium tetrakis(4-chlorophenyl)borate as lipophilic salt, and o-nitrophenyloctyl ether as plasticizer. The sensor exhibits a linear response over the concentration range 10−1-10−5 mol l−1 BaCl2 with a Nernstian slope of 30 mV per decade and high selectivity towards Ba2+ with respect to Li+, Na+, K+, Rb+, NH4+, Mg2+, Ca2+, Sr2+, Mn2+, Co2+, Ni2+, Cd2+, Al3+, La3+, and Ce3+ ions. The sensor response is stable over a wide pH range (4-9) and the lifetime is about 2 months. The proposed sensor is successfully applied to the determination of Ba2+contents of some rocks. 相似文献
9.
Mohammad Hossein Mashhadizadeh Abbas Shockravi Zakiyeh Khoubi Davood Heidarian 《Electroanalysis》2009,21(9):1041-1047
A new podand of 1,1′‐thia‐bis‐[1‐(chloroethan‐2‐acetamid‐α‐oxy)] naphtol was synthesized and used as a suitable carrier for Ag+ PVC membrane electrode. The electrode exhibited linear response with a Nernstian slope of (59.5±0.8 mV/decade) within a wide concentration range of 1.0×10?7 to 1.5×10?2 mol L?1 silver ions. The electrode had a fast response time of <10 s and detection limit of 8.6×10?8 mol L?1 with a working pH range from 3.7 to 9.0. The electrode was highly selective for Ag(I) ions over a large number of cations such as alkali, alkaline earth, and heavy metal ions. The proposed sensor has been applied as an indicator electrode for indirect determination of vitamin B1 in tablets by determination of Cl? ions in this compound with a standard solution of Ag(NO3). 相似文献
10.
Hasan Bagheri Abbas Afkhami Ali Shirzadmehr Hosein Khoshsafar Hamid Khoshsafar Hamed Ghaedi 《International journal of environmental analytical chemistry》2013,93(5):578-591
A novel ion selective carbon paste electrode for Cd2+ ions based on 2,2′-thio-bis[4-methyl(2-amino phenoxy) phenyl ether] (TBMAPPE) as an ionophore was prepared. The carbon paste was made based on a new nano-composite including multi-walled carbon nanotubes (MWCNTs), nanosilica and room-temperature ionic liquid, 1-Butyl-3-methylimidazolium hexafluorophosphate (BMIM-PF6). The constructed nano-composite electrode showed better sensitivity, selectivity, response time, response stability and lifetime in comparison with typical Cd2+ carbon paste sensor for the successful determination of Cd2+ ions in water and in waste water samples. The best performance for nano-composite sensor was obtained with an electrode composition of 18% TBMAPPE, 20% BMIM-PF6, 48% graphite powder, 10% MWCNT and 4% nanosilica. The new electrode exhibited a Nernstian response (29.95?±?0.10?mV?decade?1) toward Cd2+ ions in the range of 3.0?×?10?8 to 1.0?×?10?1?mol?L?1 with a detection limit of 7.5?×?10?9?mol?L?1. The potentiometric response of prepared sensor was independent of the pH of test solution in the pH range 3.0 to 5.5. It had a quick response with a response time of about 6?s. The proposed electrode showed fairly good selectivity over some alkali, alkaline earth, transition and heavy metal ions. 相似文献
11.
A new ion-selective PVC membrane electrode based on salicylaldehyde thiosemicarbazone as an ionophore is developed successfully as sensor for mercury(II) ions. The electrode shows excellent potentiometric response characteristics and displays a linear log[Hg2+] versus EMF response over a wide concentration range of 1.778×10−6-1.0×10−1 M with Nernstian slope of 29 mV per decade with the detection limit of 1.0×10−6 M. The response time of the electrode is less than 30 s and the membrane electrode operates well in the pH range of 1.0-3.0. The lifetime of the sensor is about 2 months. The electrode shows better selectivity towards Hg2+ ions in comparison with the alkali, alkaline and some heavy metal ions; most of these metal ions do not show significant interference (KPotHg,M values of the order of 10−3-10−4). The present sensor showed comparable or even better performance vis-à-vis similar PVC based ion-selective electrodes reported in literature. The sensor was also applied as an indicator electrode for potentiometric titration of Hg2+ions with I− and Cr2O72−. 相似文献
12.
《Materials Chemistry》1982,7(6):755-765
EPR and magnetic susceptibility experiments have been performed on x(V2O5) (1−x) [2B2O3 · PbO] glasses with x varying in the range 0.2 ⩽ x ⩽ 55 mol %. The modifications of the EPR spectra with the increasing of V2O5 content are explained supposing that these are the result of the superposition of two EPR signals, one with a well resolved hyperfine structure typical for isolated vanadyl ions and one consisting from a broad line without structure typical for clustered ions. The last species of ions is dominating in the glasses with x > 45 mol % V2O5.For the samples with x ⩾ 35 mol % V2O5 the reciprocal magnetic susceptibility follows the Curie behaviour. From magnetic data and considering that only V4+ and V5+ ions occur in the studied glasses we have estimated the V4+ ions content as well as the NV4+/NV5+ ratio, the last being approximately constant+ ∼ 0.14. 相似文献
13.
V. G. Maiorov V. Ya. Kuznetsov A. I. Nikolaev N. L. Mikhailova O. A. Zalkind G. I. Kadyrova V. K. Kopkov 《Russian Journal of Applied Chemistry》2012,85(12):1820-1826
Solutions containing 500 g L?1 Nb2O5 were obtained by sintering Nb2O5 with potash followed by leaching with water. The potassium niobate released from niobium(V) alkaline solutions was examined with an application of methods of physical and chemical analysis. Hydrates K8Nb6O19·4H2O and K7.5[H0.5Nb6O19]·14H2O were first obtained. 相似文献
14.
I. V. Kul’bakin S. V. Fedorov A. V. Vorob’ev V. V. Belousov 《Russian Journal of Electrochemistry》2013,49(9):878-882
Transport properties (conductivity, transport numbers of oxygen ions, oxygen permeability) are studied for new composites of ZrV2O7-25, 30, 35, 40 mol % of V2O5 with a liquid-channel grain boundary structure (LGBS) at 680–740°C. It is shown that the composite of ZrV2O7-40 mol % of V2O5 with LGBS has high selective oxygen permeability of 1.1 × 10?8 mol cm?2 s?1 (T = 740°C, $P'_{O_2 } $ = 0.21 atm, $P''_{O_2 } $ = 0.003 atm, L = 2 mm) and can be used as an ion-transport membrane for separation of oxygen from air. 相似文献
15.
Victor L. Cherginets Tatyana P. Rebrova Tamara V. Ponomarenko Alexander L. Rebrov Oleg I. Yurchenko 《国际化学动力学杂志》2019,51(1):37-41
A comparative investigation of a complex process of the interaction between CCl4 vapor and oxide ions O2– (carbochlorination) in K2SrCl4 and KSr2Cl5 melts at 973 K was performed by the potentiometric method using Pt(O2)|ZrO2(Y2O3) membrane oxygen electrode as reversible to oxide ion. The analysis of the limiting stages of this process was made on the basis of van't Hoff diagrams. The entire process can be divided into three stages with corresponding limiting processes: the rate of CCl4 dissolution in the melts for stage 1, the chemical reaction in the melts for stage 2, and the rate of the contamination of the melts with oxygen-containing admixtures for the stage 3. The rate constants of the carbochlorination process in both melts at 973 K were calculated using the data corresponding to stage 2 as (4.4 ± 0.25) × 105 kg mol−1 min−1 for K2SrCl4 and (1.83 ± 0.5) × 105 kg mol−1 min−1 for KSr2Cl5. The final concentration of oxide ions after the treatment is higher ( = (1.6 ± 0.7) × 10−7 mol kg−1 for KSr2Cl5 and = (2.5 ± 1.3) × 10−8 mol kg−1 for K2SrCl4 melt, respectively). This corresponds to the difference in the oxoacidic properties of the studied melts. 相似文献
16.
The preparation and study of electrochemical properties of a graphite screen-printed electrode (SPE) modified with the GO/Fe3O4@SiO2 (GO is graphene oxide) nanocomposites are described. The morphologies of the GO/Fe3O4@SiO2 nanocomposites were examined by scanning electron microscopy. The electrochemical oxidation of vitamin B6 (pyridoxine) on SPE modified with the GO/Fe3O4@SiO2 nanocomposite was investigated by cyclic voltammetry, differential pulse voltammetry, and chronoamperometry. Under optimum conditions (pH 7.0), the vitamin B6 oxidation at the surface of the modified SPE occurs at a potential about 190 mV less positive than that at the unmodified SPE. A linear voltammetric response for vitamin B6 was obtained in the concentration range 1.0?10 6—9.0?10 4 mol L–1 with a detection limit of 5.2?10 7 mol L–1 using differential pulse voltammetry. The developed sensor was also successfully applied for determination of trace level of vitamin B6 in both the standard vitamin B6 sample and biological samples (urine). 相似文献
17.
In the present study, a cauliflower‐like NiCo2O4?Zn/Al layered double hydroxide (NiCo2O4?Zn/Al LDH) nanocomposite was used as a novel electrode material for the sensitive and selective determination of pyridoxine (vitamin B6). The structure and morphology of the as‐prepared nanocomposite were characterized by X‐ray diffraction (XRD), FT‐IR, field emission scanning electron microscopy (FESEM) and energy dispersive X‐ray spectroscopy (EDX). The NiCo2O4?Zn/Al LDH nanocomposite exhibited excellent electrocatalytic ability in the oxidation of pyridoxine, which could result from the synergistic effect of the two components. The developed sensor also provided a selective determination of pyridoxine in the presence of other species such as vitamins (B1, B2, B12 and ascorbic acid), inorganic ions and biomolecules. The fabricated sensor showed a good linear response for pyridoxine over the concentration ranges 2×10?7–2.0×10?4 mol L?1 with a low detection limit of 8.6×10?8 mol L?1. Finally, the proposed method was successfully applied for the determination of pyridoxine in commercial tablets and plasma samples with satisfactory results. Furthermore, this novel sensor displayed superior benefits in terms of stability, sensitivity, repeatability and cost. The present work aims to expand NiCo2O4 based nanocomposites to sensor fields and promote the development of pyridoxine sensors. 相似文献
18.
《Electroanalysis》2017,29(11):2526-2532
An amperometric bi‐enzyme sensor for detection of organophosphorus pesticides (OPs) with phenolic leaving groups, which are not electroactive, is presented in this work. The biosensing platform was created by a simple, controllable, and reproducible one‐step electrodeposition onto the surface of a glassy carbon electrode of a chitosan bionanocomposite with entrapped carboxylated multi walled carbon nanotubes, organophosphorus hydrolase (OPH), and horseradish peroxidase (HRP). The OPs determination involved a sequence of OPH and HRP‐catalyzed reactions resulting in phenolic radicals production, which were quantified by registering the current of their reduction at a potential of −50 mV vs. Ag, AgCl/KClsat.The developed sensor was applied for the determination of prothiofos, as an example. At optimized conditions (pH 7.25 and H2O2 concentration 200 μmol L−1), a LOD as low as 0.8 μmol L−1 was attained, while the linear concentration range was extended from 2.64 μmol L−1 up to 35 μmol L−1. The main advantage of the proposed bi‐enzyme sensor is its selectivity toward the OPs with phenolic leaving groups, excluding the interference of the nitrophenyl‐substituted OPs. 相似文献
19.
Li Tian Yongjia Feng Yanjuan Qi Binbin Wang Yinran Chen Xueyan Fu 《Mikrochimica acta》2012,177(1-2):39-45
We report on a novel non-enzymatic sensor for hydrogen peroxide (HP) that is based on a biocomposite made up from chitosan (CS), hemoglobin (Hb), and silver nanoparticles (AgNPs). The AgNPs were prepared in the presence of CS and glucose in an ultrasonic bath, and CS is found to act as a stabilizing agent. They were then combined with Hb and CS to construct a carbon paste biosensor. The resulting electrode gave a well-defined redox couple for Hb, with a formal potential of about ?0.17?V (vs. SCE) at pH?6.86 and exhibited a remarkable electrocatalytic activity for the reduction of HP. The sensor was used to detect HP by flow injection analysis, and a linear response is obtained in the 0.08 to 250?μM concentration range. The detection limit is 0.05?μM (at S/N?=?3). These characteristics, along with its long-term stability make the sensor highly promising for the amperometric determination of HP. Figure
(A) FIA i–t graphs of the different concentrations of H2O2 at CS/Hb/AgNP/CPE in the PBS (pH?6.86). Applied potential: ?0.4?V. (1) 0.8?×?10?6?mol?L?1, (2) 2.4?×?10?6?mol?L?1, (3) 4?×?10?6?mol?L?1 (B) Plot of catalytic peak currents vs. the concentration of H2O2. 相似文献
20.
G. M. Rozantsev S. M. Vavilova E. E. Belousova 《Russian Journal of Inorganic Chemistry》2007,52(9):1478-1485
Complex formation in the Nb6O 19 8? -WO 4 2? -H+-H2O system with c Nb : c W = 1 : 5 and varied c Nb + W 0 = 10?2, 5 × 10?3, 2.5 × 10?3, and 10?3 mol/L) has been studied. Distribution diagrams were simulated for individual niobium(V) and tungsten(VI) isopolyanions and mixed isopolyniobotungstates for $Z = \frac{{c_{H^ + }^0 }}{{c_{Nb + W}^0 }} = 0 - 3.0$ in an NaCl background electrolyte. We have shown that isopolyniobotungstates-6 of composition H x NbW5O 19 (3 ? x)? are formed via H x Nb n W6?n O 19 (2 + n ? x)? (n=2, 3, 5) ions. The concentration formation constants and thermodynamic formation constants of isopolyniobotungstate anions (IPNTAs) in aqueous solution have been calculated. Salt Tl3NbW5O19·9H2O has been synthesized and identified by chemical analysis and IR spectroscopy. 相似文献