Tetrakis(4-N,N-dimethylaminobenzene)porphyrinato]manganese(III) acetate as a novel carrier for a selective iodide PVC membrane electrode.

[5,10,15,20-Tetrakis(4-N,N-dimethylaminobenzene)porphyrinato]Mn(III) acetate (MnTDPAc) was applied as an ionophore for an iodide-selective PVC membrane electrode. The influences of the membrane composition, pH of the test solution and foreign ions on the electrode performance were investigated. The sensor exhibited not only excellent selectivity to iodide ion compared to Cl- and lipophilic anions such as ClO4- and salicylate, but also a Nernstian response with a slope of -59.4 +/- 1.2 mV per decade for iodide ions over a wide concentration range from 1.0 x 10(-2) to 7.5 x 10(-6) M at 25 degrees C. The potentiometric response was independent of the pH of the solution in the pH range of 2 - 8. The electrode could be used for at least 2 months without any considerable divergence in the potential. Good selectivity for iodide ion, a very short response time, simple preparation and relatively long-term stability were the silent characteristics of this electrode. It was successfully used as an indicator electrode in the potentiometric titration of iodide ions, and also in the determination of iodide from seawater samples and drug formulations.     

Potentiometric sensor for sensitive and selective detection of heparin

A polymeric membrane ion-selective electrode for determination of heparin is described in this paper.Protamine is incorporated into the organic membrane phase and functions as sensing element for selective recognition of heparin.The proposed membrane electrode exhibits high selectivity for heparin over lipophilic anions such as thiocyanide and salicylate.The potentiometric response to the concentration of heparin is Unear in the range of 0.01-0.4 U/mL and a lower detection limit of 0.005 U/mL can be achieved.     

以单环有机锡配合物为载体的水杨酸根阴离子选择电极的研究

Two new cyclic pentacoordinative organotin(Ⅳ) complexes, 2,4-dihydroxyacetophenone tribenzyltin(HAPTBT) and 2,4-dihydroxyacetophenone triphenyltin(HAPTPT) were synthesized and used as anion ionophore for PVC membrane electrode. The new electrodes exhibit specificity selectivity for salicylate. The electrode based on HAPTBT as a neutral carrier displays a highly potentiometric response to salicylate and an anti-Hofmeister selectivity sequence in the following order: Sal^- ＞ SCN^- ＞ I^- ＞ NO₂^- ＞ Br^- ＞ Cl^- ＞ ClO₄^- ＞ NO₃^- ＞ SO₄^2-. The electrode has the advantages of fast response, stability and reproducibility, simplicity. The response mechanism is discussed in view of UV spectroscopy technique. The results show that there are close relationship between the potentiometric response characteristics and structure of organotin(Ⅳ) complexes. The electrode was applied to medicine analysis with satisfactory results.     

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.     

Calixarene-based potentiometric ion-selective electrodes for silver

Four lipophilic sulphur and/or nitrogen containing calixarene derivatives have been tested as ionophores in Ag(I)-selective poly (vinyl chloride) membrane electrodes. All gave acceptable linear responses with one giving a response of 50 mV/dec in the Ag(I) ion activity range 10(-4)-10(-1)M and high selectivity towards other transition metals and sodium and potassium ions. This ionophore was also tested as a membrane coated glassy-carbon electrode where the sensitivity and selectivity of the conventional membrane electrode was found to be repeated. The latter electrode was then used in potentiometric titrations of halide ions with silver nitrate.     

Poly(vinyl chloride) membrane cesium ion-selective electrodes based on lipophilic calix[6]arene tetraester derivatives

New lipophilic tetraesters of calix[6]arene and calix[6]diquinone are investigated as cesium ion-selective ionophores in poly(vinyl chloride) membrane electrodes. For an ion-selective electrode based on calix[6]arene tetraester I, the linear response is 1x10(-6)-1x10(-1) M of Cs(+) concentrations. The selectivity coefficients for cesium ion over alkali, alkaline earth and ammonium ions are determined. The detection limit (log a (Cs (+))=-6.31) and the selectivity coefficient (log k (Cs (+),Rb (+))(pot )=-1.88) are obtained for polymeric membrane electrode containing calix[6]arene tetraester I.     

A novel salicylate-selective electrode based on a Sn(IV) complex of salicylal-imino acid Schiff base

A novel poly(vinyl chloride) membrane electrode with high selectivity toward salicylate (Sal^–), based on the use of the salicylal-imino acid Schiff base dibenyl complex of Sn(IV) [Sn(IV)-SIADBen] as ionophore is described. The influence of lipophilic charged additives on the performance of the electrode was studied. The results suggested that Sn(IV)-SIADBen according to a positively-charged carrier mechanism. The influence of several other variables was investigated in order to optimize the potentiometric response and selectivity of the electrode. The electrode based on Sn(IV)-SIADBen, with 30.44 wt% PVC, 64.55 wt% plasticizer [dioctyl phthalate (DOP)], 3.81 wt% ionophore, and 1.2 wt% anionic additive exhibited a linear response for the Sal^– ion over the concentration range 1.0×10^–1 to 2.5×10^–6 mol l^–1, and displayed an anti-Hofmeister selectivity sequence as follows: salicylate perchlorate > thiocyanate > benzoate > iodide > nitrate > chloride > nitrite acetate > citrate > sulfate. UV-Visible absorption spectra were used to examine the specific interaction of salicylate with the ionophore. The electrode was applied to clinical medical analysis, and the results obtained were consistent with those obtained by conventional methods.     

Optical sensor for salicylic acid and aspirin based on a new lipophilic carrier for aromatic carboxylic acids

Summary The optode with fair selectivity for salicylate and aspirin is based on the use of a new lipophilic carrier for aromatic carboxylic acids, namely (±) n-butyl O-(1-naphthylaminocarbonyl) lactate (BNAL). The sensing scheme involves co-extraction of both salicylate anion and a proton from the aqueous sample medium into a pvc layer using BNAL as a salicylate carrier, and a pH-sensitive dye as a lipoid proton carrier, both contained in the pvc membrane. BNAL transports the salicylate anion into the pvc lipid membrane. In order to maintain electro-neutrality, the proton carrier dye simultaneously extracts a proton into the pvc membrane, thereby becoming protonated. As a result, the dye undergoes a colour change which is detected via measurement of fluorescence intensity. The sensor is fully reversible and has a dynamic range from 0.1 to 30 mmol/l salicylate at pH 5.00, but the response function is highly pH-dependent. The effect of 25 interfering anions was investigated, and optical selectivity coefficients were determined. It is also shown that by proper variation of the membrane composition, selectivities for other carboxy anions can be obtained. The method has been applied to determine aspirin in tablets using flow injection analysis, and the results were found to be satisfactory.On leave of absence from the Department of Chemistry, Nankai University, CN-300071 Tianjin, P. R. China     

Determination of hardness in tapwater and upland soil extracts using a long-term stable divalent cation selective electrode based on a lipophilic acrylate resin as a membrane matrix

A divalent cation-selective electrode, which utilizes a lipophilic resin as a matrix for the sensing membrane, and which has long-term stability has been developed. The sensing membrane is a lipophilic acrylate resin which is impregnated with a solution of 1-decylalcohol and the calcium salt of bis[4-(1,1,3,3-tetramethylbutyl) phenyl] phosphate at concentrations of 0.08 g ml(-1) each. The electrode exhibited nearly equal selectivity to Ca(2+) and Mg(2+) ions and could be used as a water hardness sensor. The electrode shows a Nernstian response with a slope of 29 mV decade(-1) to both Ca(2+) and Mg(2+) ions in the concentration range from 10(-5) M to 10(-1) M and could be used in the pH range from 3 to 10 for the determination of 10(-3) M Ca(2+) and Mg(2+) solutions. The initial performance of the electrode could be maintained for 1 year, since the lifetime test of the electrode was conducted in tapwater at a continuous flow rate of 4 ml min(-1). The hardnesses of tapwater and upland soil extracts were determined using the developed electrode and the analytical results were in good agreement with those obtained by chelatometric titration using an EDTA solution as the titrant. A coefficient factor of correlation 0.998 was obtained between the electrode method and titrimetry. The long-term stability of the electrode was found to be due to strong affinity of 1-decylalcohol to the lipophilic acrylate resin.     

Membrane-dialyzer injection loop for enhancing the selectivity of anion-responsive liquid-membrane electrodes in flow systems Part 2. A selective sensing system for salicylate

An electrode-based flow-injection system suitable for the direct determination of salicylic acid is described. The system utilizez a tubular polymer membrrane electrode based on manganese(III) tetraphenylporphyrin chloride to sense salicylate ions formed in a recipient buffer solution held within the upper channel of a flow-through membrane dialyzer assembly. Samples containing salicylic acid are manually intoduced into the lower channel of the dialysis unit, in which a thin silicone rubber membrane separates the two channels. The analyte is trapped across the membrane as salicylate ions within a static layer of an appropriate recipient buffer. After a fixed trapping time, the recipient plug is flushed to the electrode in a conventional flow-injection manner. Peak potentials observed are logarithmically related to the salicylic acid concentrations in the original sample. Without the dialysis unit, the electrode response to salicylate is nearly Nernstian over the range 2 × 10^?6?10^?2 M. In the complete flow/dialysis system, near Nernstian response was achieved for 10^?4?10^?2 M salicylate with a 2-min trapping time. Detection limits can be altered by changing the trapping time. Anionic salicylate can be determined by acidifying the sample. The resulting system offers very high selectivity for salicylate (as salicylic acid) over most inorganic and organic anions normally found in blood. Preliminary studies demonstrate the practical application of this system for the determination of salicylate in serum.     

Application of Tetra Cyclohexyl Tin(IV) as an Anionic Carrier for the Construction of a New Salicylate Membrane Sensor

A new tin complex namely tetracyclohexyl tin(IV) (TCHT) was synthesized and used as the ion carrier for the construction of a highly selective salicylate sensor. This sensor shows a Nernstian response to salicylate ions over a very wide concentration (1.0 × 10^?7–1.0 × 10^?1 M) in a pH range of 5.5–10.5. The optimum selectivity and response could be obtained for a membrane incorporating 30% PVC, 61% BA, 3% of cationic additive (HTAB) and 6% of TCHT. The response time of the electrode is very short in the whole concentration range (15 s). The electrode also shows an excellent discriminating ability for salicylate ions with respect to the most common organic and inorganic anions including chloride, sulfate, nitrate, nitrite, cyanide, sulfite, iodide, thiocyanate, phosphate, acetate, oxalate, citrate, and tartarate ions. The detection limit of the proposed sensor is 8.0 × 10^?8 M. The electrode was successfully used for determining the concentration of salicylate ion in synthetic serums.     

新型杯芳烃为载体的铅离子选择电极

报道了5,11,17,23-四（1,1-二甲基乙基）-25,27-二羟基-26,28-二[（2-丙酰胺）乙氧基]杯[4]芳烃1的合成及以此化合物为载体研制了PVC膜铅离子选择电极。研究了不同极性的膜增塑剂和亲脂性阴离子位点对铅离子选择电极响应性能的影响,测定了铅离子选择电极的性能。铅离子选择电极对铅离子表现出优良的能斯特响应和高选择性,能在pH4.0-6.5的范围内使用,该电极可作为电位滴定的指示电极。     

Neutral bidentate organophosphorus compounds as novel ionophores for potentiometric membrane sensors for barium(II)

Bis(diarylphosphine oxide) naphthalene compounds are used as novel ionophores in plasticized poly(vinyl chloride) matrix membrane sensors for barium ions. The most favorable sensor was 1,2-bis(diethylphenylphosphine oxide)naphthalene containing potassium tetrakis(4-chlorophenyl)borate as lipophilic salt and o-nitrophenyloctyl ether as plasticizer for ion-selective electrode membrane construction. The electrode showed excellent properties. It gave a linear response with a Nernstian slope of 30 mV per decade within the concentration range 10(-1)-10(-5) mol L(-1) BaCl2. The electrode exhibits a high selectivity towards Ba2+ with respect to Li+, Na+, K+, Rb+, Cs+, NH4+, Ag+, Mg2+, Ca2+, Sr2+, Mn2+, Fe2+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+, Pb2+, Al3+, La3+, and Ce3+ ions. The electrode response was stable over a wide pH range (3-11). The lifetime of the electrode was about 2 months. It was successfully applied to the determination of Ba2+ contents in some rocks.     

Design of Schiff base complexes of Co(II) for the preparation of iodide-selective polymeric membrane electrodes

The response characteristics of some iodide-selective solvent polymeric membrane electrodes based on with N,N'-bis(salicylaldehyde-n-octyl) diimine cobalt(II) (Co(II)SAODI) which is a more lipophilic substitute for a previously reported iodide-carrier are described. The electrode doped with Co(II)SAODI into a plasticized poly(vinyl chloride) membrane exhibits an anti-Hofmeister selectivity pattern with high selectivity toward iodide, long lifetime and small interference from H(+). Quartz crystal microgravimetric measurements and ac impedance experiments show that the excellent selectivity for iodide is related to the unique interaction between the carriers and iodide and steric effect associated with the structure of the Schiff base ligands.     

Ion-selective electrodes based on siderophores: Salicylate response of a ferrimycobactin membrane

Siderophores are compounds which transport iron across cell membranes; mycobactins are hydrophobic siderophores and were expected to be suitable for inclusion in the organic membrane phase of a liquid ion-exchange electrode responsive to iron(III) ions. In practice, no iron(III) response was obtained from mycobactin membranes (in a variety of solvents), but they did respond to salicylate ion with a sensitivity of 27–29 mV/decade over the range 2 × 10^?3–3 × 10^?2 mol l^?1 at pH 7. The effects of pH and interference by other anions are described and the possible mechanisms of the electrode are discussed. The selectivity of the electrode for salicylate is better than that of quaternary ammonium liquid ion-exchange electrodes.     

A novel ethacrynic acid sensor based on a lanthanide porphyrin complex in a PVC matrix

Lanthanide porphyrin complexes synthesized by a solid state method were used to prepare a novel ethacrynic acid (EA) sensor. The sensor, based on pentane-2,4-dionato(meso-tetraphenylporphinato)terbium [TbTPP(acac)] with an optimized membrane composition, exhibits a Nernstian response to EA- ion in the concentration range 7.4 x 10(-6)-1.0 x 10(-1) mol l-1 with a pH range from 3.2 to 6.8 and a fast response time of 30 s. The electrode shows improved selectivity towards EA- ion with respect to common co-existing ions compared with the previously reported EA sensor. As electroactive materials, lanthanide porphyrin complexes show better potentiometric response characteristics than copper porphyrin complexes. The effect of solvent mediators and lipophilic ion additives was studied and the experimental conditions were optimized. The electrode was applied to the determination of EA in human urine samples with satisfactory results.     

Study of Cobalt(III) Corrole as the Neutral Ionophore for Nitrite and Nitrate Detection via Polymeric Membrane Electrodes

Cobalt(III) 5,10,15‐tris(4‐tert‐butylphenyl) corrole was synthesized and incorporated into plasticized poly(vinyl chloride) membranes and studied as a neutral carrier ionophore via potentiometry. This cobalt(III) complex has binding affinity to nitrite, and the resulting membrane electrode yields reversible and Nernstian response toward nitrite. Enhanced nitrite selectivity is observed over other anions, including lipophilic anions such as thiocyanate and perchlorate when an appropriate amount of lipophilic cationic sites are added to the membrane phase. Detection limit to nitrite is ca. 5 µM. Using tributylphosphate as the plasticizer with the cobalt(III) corrole species yields electrodes with enhanced nitrate selectivity.     

新型钴配合物中性载体高选择性水杨酸根电极的研究

基于经典的离子交换剂如季铵盐、季鏻盐和邻菲罗啉配合物等的溶剂聚合膜电极对阴离子呈现出Hofmeister选择性序列.目前,研究反Hofmeister行为的阴离子选择性电极已成为化学传感器研究领域的重要研究方向之一.该类电极通常以金属卟啉及其衍生物、维生素B₁₂衍生物和金属酞菁及其衍生物等作为载体,研制出了SCN^-,NO₂^-,Cl^-和I^-等选择性电极.采用席夫碱金属配合物及金属汞.     

Hydrogen ion-selective poly(vinyl chloride) membrane electrode based on a p-tert-butylcalix[4]arene-oxacrown-4

A hydrogen ion-selective poly(vinyl chloride) (PVC) membrane electrode was developed using p-tert-butylcalix[4]arene-oxacrown-4 as ionophore. Apart from the ionophore, plasticisers and lipophilic anions were blended, in various proportions, with PVC in tetrahydrofurane and mixtures so prepared were poured onto glass surfaces to form the membrane. 2-Nitrophenylpentylether has proved to be the best alternative as plasticiser and the lipophilic anions tried have turned out to have an adverse effect on the pH response. The electrode of the optimum characteristics had a composition of 2% p-tert-butylcalix[4]arene-oxacrown-4, 68.3% o-NPPE and 29.7% PVC. The electrode showed an apparent Nernstian response in the pH range 2-11 with a slope of 54.2±0.4 mV pH⁻¹ at 20±1 °C. It has a rapid potential-response to changes of pH, high ion selectivity towards lithium, sodium and potassium, and other characteristics comparable to those reported for the conventional pH glass membrane electrode. It appears to be a suitable potentiometric indicator electrode specifically for hydrofluoric acid solutions.     

基于离子液体的硫酸根离子选择电极的研究

将离子液体BMIMPF6应用于传感膜中制备硫酸根选择性电极,研究发现离子液体在电极中不仅能够提高传感膜的介电常数和传导速率,还与硫酸根离子发生相互作用,起到载体的功能。利用离子液体和硫脲的协同作用制备的电位传感器,对硫酸根离子在10-5～10-2 mol/L范围内有能斯特响应,同时具有pH干扰小,重复性好,响应时间快等特点,能够用于环境和生物医疗检测。