A 9,10-anthraquinone derivative having two propenyl arms as a neutral ionophore for highly selective and sensitive membrane sensors for copper(II) ion.

New polymeric membrane (PME) and coated graphite (CGE) copper(II)-selective electrodes based on 1-hydroxy-2-(prop-2'-enyl)-4-(prop-2'-enyloxy)-9,10-anthraquinone were prepared. The electrodes reveal linear emf-pCu2+ responses over wide concentration ranges (1.0 x 10(-5)-1.0 x 10(-1) M with a slope of 27.3 mV decade-1 for PME and 8.0 x 10(-8)-5.0 x 10(-2) M with a slope of 29.1 mV decade-1 for CGE) and very low limits of detection (8.0 x 10(-6) M for PME and 5.0 x 10(-8) M for CGE). The potentiometric response is independent of the pH of the test solution in the pH range 3.0-6.0. The proposed electrodes possess very good selectivities over a wide variety of other cations, including alkali, alkaline earth, transition and heavy metal ions, the selectivity coefficients for the CGE being much improved over those for the PME. The electrodes were used as indicator electrodes in the potentiometric titration of Cu2+ and in the recovery of copper ions from wastewater.     

冠醚化合物的合成——ⅩⅣ.二茂铁硫冠醚的合成及其银离子选择电极的研究

本文合成了两种类型6个二茂铁硫冠醚1—6,其中4—6是一类新型缩醛硫冠醚。将冠醚2—6作为传感活性物质研制成PVC膜银离子选择电报,其中以用冠醚4的电极性能最佳,对一价和二价干扰离子的选择性,远优于文献[1]结果。     

Triethylene glycol ether end-grafted carbosilane dendrimer: a potential ionophore for potassium ion recognition.

The performance of a newly synthesized carbosilane dendrimer bearing four triethylene glycol ether (TEG) units, Si(CH2CH2CH2Si(Me)2CH2CH2CH2(OCH2CH2)3Me)4 (1), as ionophores in ion-selective electrodes has been investigated. Optimization of the plasticized polyvinyl chloride membrane composition has produced electrodes that exhibit a Nernstian response for potassium ions. The best general characteristics exhibited by the electrodes were found when the membrane composition ratio of DPE:1:NaTPB:PVC 60:3:2:35 (wt%) was used. The response of the electrode was linear with a Nernstian slope of 58.3 mV/decade over the K+ ion concentration range of 1.9x10(-7) to 1.0x10(-1) M with a detection limit of 3.1x10(-7) M. The response time to achieve a 95% steady potential for the K+ concentration ranging from 1.0x10(-1) to 1.0x10(-8) M was less than 10 s, and it was found that the electrode is suitable for use within a pH range of 5.5-8.5. The selectivity coefficients (log KPotK+,Mn+)), which were determined by the fixed interference method, showed good selectivity for K+ against most of the interfering cations. The influence of this selective ion-binding behavior using electrospray ionization time-of-flight (ESI-TOF) mass spectrometric studies is discussed.     

Mercury(II) ion-selective electrodes based on heterocyclic systems

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.     

A comparative study of four 20-membered N2S4-crown ethers as ionophores for polymeric membrane silver

Four 20-membered N2S4-monoazathiacrown ethers have been synthesized and explored as neutral ionophores for Ag+-selective electrodes.Potentiometric responses reveal that the flexibility of the ligands has great effect on the selectivity and sensitivity to Ag+ions.The electrode based on ionophore 9,10,20,25-tetrahydro-5H,12H-tribenzo[b,n,r][1,7,10,16,4,13]tetrathiadiaza cycloicosine6,13-(7H,14H)-dione(C)with 2-nitrophenyl octyl ether(ο-NPOE)as solvent in a poly(vinyl chloride)(PVC)membrane matrix shows a measuring range of 1.0 × 10-6 to 1.0 × 10-3 mol/L with a Nemstian slope of 54.9 ± 0.3 mV/decade.This electrode has high selectivity for Ag+with negligible interference from many other cations and can be used in a wide pH range of 3.6-9.2.     

New conventional coated-wire ion-selective electrodes for flow-injection potentiometric determination of chlordiazepoxide.

New chlordiazepoxide hydrochloride (Ch-Cl) ion-selective electrodes (conventional type) based on ion associates, chlordiazepoxidium-phosphomolybdate (I) and chlordiazepoxidium-phosphotungstate (II), were prepared. The electrodes exhibited mean slopes of calibration graphs of 59.4 mV and 60.8 mV per decade of (Ch-Cl) concentration at 25 degrees C for electrodes (I) and (II), respectively. Both electrodes could be used within the concentration range 3.16 x 10(-6)-1 x 10(-2) M (Ch-Cl) within the pH range 2.0-4.5. The standard electrode potentials were determined at different temperatures and used to calculate the isothermal coefficients of the electrodes, which were 0.00139 and 0.00093 V degrees C(-1) for electrodes (I) and (II), respectively. The electrodes showed a very good selectivity for Ch-Cl with respect to the number of inorganic cations, amino acids and sugars. The electrodes were applied to the potentiometric determination of the chlordiazepoxide ion and its pharmaceutical preparation under batch and flow injection conditions. Also, chlordiazepoxide was determined by conductimetric titrations. Graphite, copper and silver coated wires were prepared and characterized as sensors for the drug under investigation.     

Ligand-modified multi-walled carbon nanotubes for potentiometric detection of silver

Three novel hybrid materials have been synthesized by ligands: N-(2-vinylsulfanyl-ethylidene)-benzene-1,2-dimine (SBD), N-pyridin-2-ylmethylene-benzene-1,2-dimine (NBD) and N-furan-2-ylmethylene-benzene-1,2-dimine (OBD), covalently linking to multi-walled carbon nanotubes (MWCNTs). These MWCNT hybrid materials were used both as ionophores and as ion-to-electron transducers to construct Ag(+) carbon paste electrodes. The resulting electrodes show higher selectivity to Ag(+) than other cations tested. Among the three electrodes, the electrode based on SBD-g-MWCNTs with optimum composition shows the best performance to Ag(+). It exhibits an excellent Nernstian response to Ag(+) in the concentration range from 8.8 × 10(-8) to 1.0 × 10(-1) M with a detection limit of 6.3 × 10(-8) M, and it can also be used over a wide pH range of 3.0-8.0 with a quick response time of 5 s. The response mechanism of the proposed electrode was also investigated by using AC impedance and UV-vis spectroscopy techniques.     

Oligocarbazoles as ligands for lead-selective liquid membrane electrodes.

Oligocarbazoles have been applied as new ionophores in liquid membrane electrodes (ISEs) destined for lead(II) determination in water samples. The oligocarbazole-containing ISEs demonstrated a close-to-Nernstian potentiometric response towards Pb2+ in the activity range 10(-7)-10(-2) M. The selectivity coefficients measured by the matched potential method (MPM) confirmed their good selectivity against common interfering mono- and doubly charged cations. The oligocarbazole-containing ISEs do not respond towards protons. Their applicability has been checked by performing the recovery test while using a sample of wastewater.     

双酰胺双(3'-正十五烷基-苯并-15-冠-5)PVC膜钾离子选择电极的研究

本文合成了十个双酰胺型双(3'-正十五烷基-苯并-15-冠-5)化合物, 制成的PVC膜钾离子选择电极, 性能优良.     

Cation selectivity of ionophores based on tripodal thiazole derivatives on benzene scaffold

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.     

Polydiphenylamine-dodecyl sulfate films for the simultaneous amperometric determination of electroinactive anions and cations in ion-exclusion cation-exchange chromatography

An amperometric detector with two working electrodes both modified with polydiphenylamine-dodecyl sulfate (PDPA-DS) was successfully used for the simultaneous determination of electroinactive anions (SO42-, Cl-, NO3-) and cations (Na+, NH4+ and K+) in single-column ion-exclusion cation-exchange chromatography (IEC-CEC). The PDPA-DS chemical modified electrode (CME) was based on the incorporation of dodecyl sulfate (DS) into PDPA by electropolymerization of diphenylamine in the presence of sodium dodecyl sulfate. The electrochemical responses against the anions and cations at the PDPA-DS CME in differential pulse voltammetry were studied. A set of well-defined peaks of electroinactive anions and cations were obtained. The anions and cations were detected conveniently and reproducibly in a linear concentration range 0.01-5.0 mmol/L and their detection limits were in the range 5-9 micromol/L at a signal-to-noise ratio of 3 (S/N = 3). The proposed method was quick, sensitive and simple and was successfully applied to the analysis of lake water samples. The working electrode was stable over one week period of operation with no evidence of chemical and mechanical deterioration.     

Calixazacrown ethers for copper(II) ion-selective electrode

Five novel 1,3-alternate calix[4]azacrown ethers having 2-picolyl, 3-picolyl, and benzyl unit on the nitrogen atom were synthesized and used as ionophores for transition metal-selective polymeric membrane electrodes. The electrode based on 2-picolyl armed 1,3-alternate calix [4] azacrown ether exhibited Nernstian response toward copper (II) ion over a concentration range (10(-4.5) M-10(-2.5) M). The detection limit was determined as 10(-5) M in pH 7 and the selectivity coefficients for possible interfering cations were evaluated. Anions in the sample solution strongly affected the electrode response.     

Comparative studies of mercapto thiadiazoles self-assembled on gold nanoparticle as ionophores for Cu(II) carbon paste sensors

Comparative studies of the potentiometric behavior of three mercapto compounds [2-((5-mercapto-1,3,4-thiadiazol-2-ylimino)methyl)phenol] (MTMP), [5-(2-methoxy benzylidene amino)-1,3,4-thiadiazole-2-thiol] (MBYT) and [5-(pyridin-2-ylmethyleneamino)-1,3,4-thiadiazole-2-thiol] (PYTT) self-assembled on gold nanoparticles (GNPs) as ionophores in carbon paste electrodes (CPEs) have been made. These mercapto thiadiazole compounds were self-assembled onto gold nanoparticles and then incorporated within carbon paste electrode. The self-assembled ionophores exhibit a high selectivity for copper ion (Cu²⁺), in which the sulfur and nitrogen atoms in their structure play a role as the effective coordination donor site for the copper ion. These carbon paste electrodes were applied as indicator electrodes for potentiometric determination of copper ions. The sensor based on PYTT exhibits the working concentration range of 4.0 × 10⁻⁹ to 7.0 × 10⁻² M and a Nernstian slope of 28.7 ± 0.3 mV decade⁻¹ of copper activity. The detection limit of electrode was 1.0 × 10⁻⁹ M and potential response was pH independent across the range of 3.0-6.5. It exhibited a quick response time of <5 s and could be used for a period of 45 days. The ion selectivity of this electrode for Cu²⁺ was over 10⁴ times that for other metal cations. The application of prepared sensors has been demonstrated for the determination of copper ions in spiked water and natural water samples.     

Characterization and application of humic acid modified carbon electrodes

Four routes for the modification of carbon electrodes with humic acids and the determination of three divalent metallic cations were studied. The determination of bound Fe²⁺, Cu²⁺ and Ni²⁺ was performed by cyclic and square wave voltammetry using either a batch or flow analysis system. Using the FIA system and SWV, linear relationships between the oxidation (or reduction) current and the cations concentration were obtained with the modified electrodes, while no signals were obtained for the same conditions for bare carbon electrodes. The system can be used to study the interaction between a wide range of electroactive cations and humic substances; however, the performance as an analytical tool is limited due to the high limits of detection (μM). However, some advantages like simplicity, short analysis time, inexpensive instrumentation needs and miniaturization capabilities are remarkable.     

Novel PVC-based membrane sensors selective for vanadyl ions

Poly(vinyl chloride) based membranes of di-(2-ethylhexyl)phosphoric acid (DEHPA) and dibutyl(butyl)phosphonate (DBBP) have been prepared and investigated as VO²⁺-selective sensors. The membranes containing DEHPA/DBBP and sodium tetraphenylborate, an anion excluder, show near-Nernstian/Nernstian response in the concentration range 10⁻⁵–10⁻¹ M. The sensors exhibit a fast response time and good selectivity for VO²⁺ over a number of other cations. Quantitative determination of vanadium in waste V₂O₅ catalyst has been achieved by these sensors and they have also been used as indicator electrodes for the determination of the end point in the potentiometric titration of VO²⁺ against EDTA.     

铋(Ⅲ)-卤素络阴离子选择电极的研究

我们曾报导了PVC膜四碘络铋离子选择电极的研制。现又研制了铋(Ⅲ)-溴,铋(Ⅲ)-氯的络阴离子PVC膜选择电极。本文比较了三种铋(Ⅲ)-卤素络阴离子选择电极的主要性能,并对络阴离子电极配位体的选择条件及阳离子的干扰规律进行了讨论。     

Membrane electrodes for determination of some beta-blocker drugs

Five poly(vinyl chloride) (PVC) matrix membrane electrodes responsive to the beta-blockers atenolol (AT), bisoprolol fumarate (BI), timolol maleate (TI), and levobunolol HCl (LV) were developed and characterized. A precipitation-based technique with ammonium reineckate anion as an electroactive material in PVC matrix with AT, BI, TI, and LV cations was used for fabrication of Electrodes 1-4, respectively. Electrode 5 fabrication was based on precipitation of LV cation with tungstophosphate anion as an electroactive material. Fast and stable Nernstian responses at 1 x 10(-2)-1 x 10(-7) M for different beta-blockers over the pH range of 2-8 were found for these electrodes, which were evaluated according to International Union of Pure and Applied Chemistry recommendations. The method was successively applied for the determination of beta-blockers in their pharmaceutical formulations. Validation of the method according to quality assurance standards showed the suitability of the proposed electrodes for use in the quality control assessment of these drugs. The recoveries for the determination of the beta-blocker drugs by the 5 proposed selective electrodes were 100.1 +/- 0.7, 99.9 +/- 0.8, 100.0 +/-1.1, 100.5 +/- 1.1, and 100.6 +/- 0.7% for Sensors 1-5, respectively. Statistical comparison between the results obtained by this method and the official method of the drugs was performed and no significant difference was found.     

Potentiometric sensor for the high throughput determination of tetramisole hydrochloride

The electrochemical response characteristics of poly(vinyl)chloride (PVC) based membrane sensors for determination of tetramisole hydrochloride (TmCl) is described. The membranes of these electrodes consist of tetramisole-tetraphenyl borate (Tm-TPB), chlorophenyl borate (Tm-ClPB), and phosphotungstate (Tm(3)-PT) ion associations dispersed in a PVC matrix with dibutylpthalate as a plasticizer. The electrodes were fully characterized in terms of composition, life span, usable pH range, and working concentration range and ionic strength. The electrodes showed Nernstian response over the concentration ranges of 7.4 x 10(-7) to 1.0 x 10(-2) M, 1.7 x 10(-6) to 1.0 x 10(-2) M, and 5.6 x 10(-6) to 1.0 x 10(-2) M TmCl, respectively, and were applied to the potentiometric determination of tetramisole ion in pure solutions and pharmaceutical preparations. The potentiometric determination was also used in the determination of tetramisole in pharmaceutical preparations in four batches of different expiration dates. The electrodes exhibited good selectivity for TmCl with respect to a large number of excipients such as inorganic cations, organic cations, amino acids, and sugars. The solubility product of the ion-pair and the formation constant of the precipitation reaction leading to the ion-pair formation were determined conductometrically. The new potentiometric method offers the advantages of high-throughput determination, simplicity, accuracy, automation feasibility, and applicability to turbid and colored sample solutions.     

Poly(4-amino-2,1,3-benzothiadiazole) films: preparation,characterization and applications

The electrochemical preparation of novel poly(4-amino-2,1,3-benzothiadiazole) films on a platinum surface in sulfuric aqueous medium by cyclic voltammetry is described. The resulting polymeric electrodes were characterized by FT Raman spectroscopy, scanning electron microscopy and potentiometry. Spectroscopic measurements confirmed the participation of the amino group and sulfur atom in the process that forms the granular structure of poly(ABTD). Potentiometric results showed the response of the poly(ABTD) film towards divalent cations such as Zn²⁺ and Cd²⁺ in the concentration range from 10^?7 up to 10^?2 mol L^?1. A cooperative combination of the cation-sensitive poly(ABTD) electrodes in an array with pH- and anion-sensitive electrodes was able to recognize different Czech beers.     

Liquid membrane electrodes for the selective determination of nicotine in cigarette smoke

Five liquid membrane electrode systems responsive to the nicotinium cation are described. These electrodes are based on the use of the ion-association complexes of the nicotinium cation with tetraphenylborate, 5-nitrobarbiturate, flavianate, reineckate and picrolonate counter anions in nitrobenzene solvent as ion-exchange sites. The performance characteristics of these electrodes, evaluated according to IUPAC recommendations, reveal fast, stable and near-Nernstian responses for 10(-2)-10(-5) M nicotine over the pH range 3.5-7. Many inorganic and organic cations do not interfere. The direct potentiometric determination of 3 micrograms ml-1-1.6 mg ml-1 of nicotine in aqueous solutions showed an an average recovery of 99.5% and a mean standard deviation of 1.2%. The electrodes were also used for monitoring the titration of nicotine with sodium tetraphenylborate, measuring the pK of nicotine and determining nicotine in the smoke from different cigarettes. The results compare favourably with those obtained by the standard gas chromatographic method.