Synthesis of Mn(Ⅲ) Complexes of New "Tailed" Porphyrins and Their Application as Carriers for PVC Membrane SCN-Anion-Selective Electrode

Three new 'tailed' porphyrins and their corresponding Mn(Ⅲ) metalloporphyrins were synthesized and characterized. The potentiometric response characteristics of the PVC membrane electrode based on the Mn(Ⅲ) complexes of the three new 'tailed' porphyrins toward SCN- have been studied.

Erbium(Ⅲ) PVC membrane sensor based on N-(benzyloxycarbonyloxy)succinimide as a new neutral ionophore

In this study,a new Er^3＋ sensor based on N-（benzyloxycarbonyloxy）succinimide（BCS） as a neutral carrier has been constructed. The sensor exhibits potential linear response with a Nernstian slope of 20.5±0.4 mV/decade in the concentration range of 1.0×10^-6to 1.0×10^-2mol/L of Er^3＋.It has a very short response time（10 s）,detection limit of 6.3×10^-7 mol/L and a good selectivity relative to a wide variety of other metal ions including common alkali,alkaline earth,heavy,and transition metal ions.It can be used in the pH range of 2.5-10.6 without any considerable divergence in potentials.The proposed sensor was successfully applied for the recovery of Er^3＋ ions spiked in tap and river water samples.

Fabrication of a Ho^(3+)-PVC membrane sensor based on N-phenyl-2-(thiophen-2-ylmethylene)hydrazinecarbothioamide for determination of holmium ions

In this research,a new poly（vinyl chloride）（PVC） membrane sensor for Ho^3＋ ion based on N-phenyl-2-（thiophen-2- ylmethylene）hydrazinecarbothioamide（PHC） as an ionophore was prepared.This sensor demonstrated good selectivity and sensitivity towards the holmium ion in comparison with variety of cations,including alkali,alkaline earth,transition and heavy metal ions.The effect of membrane composition and pH on the response properties of the electrode was investigated.In detail,the suggested sensor exhibited a Nernstian behavior（with a slope of 20.4±0.3 mV decade^-1） in the range of 1.0×10^-6 to 1.0×10^-2 mol/L with a detection limit of 6.2×10^-7 mol/L.The response time was relatively quick in the whole concentration range（～5 s）.The sensor usage was found to be at least 10 weeks in a pH range of 3.3-10.9.It was successfully applied in determination of fluoride ions in mouth wash preparations.

Potentiometric determination of diclofenac in pharmaceutical formulation by membrane electrode based on ion associate with base dye

The characteristics, performance and application of membrane electrode based on ion associate of diclofenac with base dye Safranine T are described. The electrode response to diclofenac has the sensitivity of 47 ± 1.0 mV decade(?1) over the range of 5 × 10(?5) to 5 × 10(?2) mol/L at pH 6–12, and the detection limit of 3.2 × 10(?5) mol/L. The electrode is easy assembled at a relatively low cost has fast response time (2–4 s) and can be used for a period up to 3.5 months without any considerable divergence in potential. The proposed sensor displayed good selectivity for diclofenac in the presence of different substances. It was used to determine diclofenac in pharmaceuticals by means of the standard addition method.

Novel Palladium （II） Selective Membrane Electrode Based on Phenyl Disulfide

PVC （a poly vinyl chloride） membrane was prepared by using phenyl disulfide as a carrier for selective determination of Pd （II） ion. The membrane can be worked well over a wide concentration range （1.0 × 106-1.0 × 10-1） M with a slope 29.53 mV/decade and a limit of detection （1.77× 10-7） M. The measured of response time was 9 s. It was found to be selective and useable within the pH range （3.0-7.0）. The lifetime of membrane sensor prepared could be used for at least 4 months. The electrode was successfully used as an indicator electrode in potentiometric titration of palladium ion with EDTA.

pH-Sensitive Polymer Matrix with Immobilized Indicator Ion Pairs

A new sensor material for monitoring pH in aqueous solutions is described. It is based on lipophilic ion pairs consisting of an anionic pH indicator Bromocresol Green and a quaternary ammonium cation cetyltri-methylammonium. The ion pairs are homogeneously distributed inside the plasticized PVC membrane. The change of pH in an aqueous solution causes the change of optical property of the indicator immobilized on the plasticized PVC membrane. The plasticized PVC membrane is sensitive in a pH range from 4.0 to 6.0.

N^1,N^2-Bis[1-(2-hydroxyphenyl)methylidene]ethanedihydrazide as a neutral ionophore for preparation of a new Ho^(3+) PVC-membrane sensor

N^1,N^2-Bis[1-（2-hydroxyphenyl）methylidene]ethanedihydrazide（MEH） was used as new compound which plays the role of an excellent ion carrier in the fabrication of a Ho（Ⅲ） membrane electrode.The electrode shows a good selectivity for Ho（Ⅲ） ion with respect to most common cations including alkali,alkaline earth,transition and heavy metal ions.This electrode has a wide linear dynamic range from 1.0×10^（-6） to 1.0×10^（-2） mol/L with a Nernstian slope of 19.8±0.3 mV per decade and a low detection limit of 5.8×10^（-7） mol/L in the pH range of 2.5-9.8,while the response time was rapid（10 s）.The suggested sensor was applied to the determination of Ho（Ⅲ） ions in tap water and river water samples.

Application of 2,2'-dithiobis(4-methylthiazole) as sensing material for construction of Lu^(3+) PVC-membrane sensor

In this work a new Lu^（3＋） PVC-membrane sensor based on 2,2＇-dithiobis（4-methylthiazole）（TMT） has been fabricated.The sensor exhibits a Nernstian slope of 19.6±0.4 mV decade（？） in the concentration range of 1.0×10~6-1.0×10~2 mol L^1 and a detection limit of 6.8×10~7 mol L^1.It could work well in the pH range of 2.7-9.6.The selectivity of the sensor against a lot of common alkaline,alkaline earth,transition,heavy metals and specially lanthanide ions was very good.

Novel Phosphate-sensitive Fluorescent Composite Matrix

Via several techniques to modify sensitive matrix for inhabiting the leakage of fluorescent indicator, a new stable sensing material for monitoring phosphates has been prepared and applied to the measurement of phosphates in artificial seawater. It is based on the reaction of PO 3- 4 with Al(Ⅲ) Morin that leads to the fluorescence quenching of the composite matrix. At pH value 4 0 and the salinity value 25 0, the response time of output signal having reached the steady state is less than 300 seconds. Its calibration graph is gained in the range of H 2PO - 4 mass concentration from 1 50 to 7 00 μg/mL with the limit of detection(3 σ/K ) 0 02 μg/mL. When it was used to measure phosphates in artificial seawater, the recovery ranged from 96 78% to 102 09%. Being stored under the proper condition, the membranes maintain sensitive for 90-120 days, and are able to be used for 50-80 times with indicator supplement.

Metal cation removal by P（VC-r-AA） copolymer ultrafiltration membranes

A series of amphiphilic copolymers containing poly（vinyl chloride-r-acrylic acid） （P（VC-r-AA）） was synthesized and used to prepare membranes via a non-solvent induced phase separation method. The prepared membranes were characterized by scanning electron microscopy, X-ray photoelectron spectroscopy, and water contact angle and zeta potential measurements. The copolymer P（VC-r-AA） chains did not dissolved in a coagulation bath, indicating that the AA segments were completely retained within the membrane. Enriching degree of AA segments in surface layer was 2 for copolymer membrane. In addition, the introduction of AA segments made the membrane electronegative and hydrophilic so that the membrane was sensitive to the solution pH. The fouling resistance, adsorption of Cu（II）, Cr（III） and Ce（IV） ions and the desorption properties of the membranes were also determined. The copolymer membranes exhibited good antifouling performance with a fouling reversibility of 92%. The membranes also had good adsorption capacities for Cu（II）, Cr（III） and Ce（IV） ions. The optimal pH for Cu（II） adsorption was 6 and the copolymer membrane has potential applications for low concentration Cu（II） removal.

Development of Chromium(Ⅲ)-selective Potentiometric Sensor by Using Synthesized Pyrazole Derivative as an lonophore in PVC Matrix and its Applications

A novel poly(vinyl chloride)membrane potentiometric sensor for chromium(Ⅲ)ions based on the use of 5,5′-(1,4-phenylene)bis(3-(naphthalen-1-yl)-4,5-dihydro-1H-pyrazole-1-carbothioamide)as a neutral ionophore was developed.The optimum composition of the best performing membrane contained ionophore,potassium tetrakis(p-chlorophenyl)borate(KTpClPB),dibutyl phthalate(DBP),and poly(vinyl chloride)(PVC)in the ratio of 5.5:1.5:55:38(mg).The sensor exhibits a working concentration range of 1.0×10^(-5)-1.0×10^(-1 )mol L^(−1) and a detection limit of 1.7×10^(-6) mol L^(−1).The sensor shows good selectivity for chromium(III)ions over a number of cations including alkali,alkaline earth,heavy and transition metals.The response time of the sensor is 8 s.In addition,the developed sensor shows good reusability and stability.The sensor operates in the wide pH range of 5.0-11.0.The sensor could be used as an indicator electrode in the quantification of Cr^(3+)ions by potentiometric titration against ethylenediaminetetraacetic acid(EDTA).Finally,this sensor was successfully used for the determination of chromium(III)in commercial water,purification water and wastewater.

A novel Ce(Ⅳ)ion-selective polyvinyl chloride membrane electrode based on HDEHP and HEH/EHP

A novel Ce（Ⅳ） ion-selective polyvinyl chloride（PVC） membrane electrode based on HDEHP and HEH/EHP as ionophore was successfully prepared. The factors affecting the response of Ce（Ⅳ） ion were investigated, such as membrane composition, internal solution, concentration of SO_4^（2–）, and acidity in test solution. The best performance was obtained using the membrane with PVC：DBP：HDEHP：HEH/EHP：OA mass ratio of 75：175：5：5：5. The proposed electrode exhibited a Nernstian slope of 30.44 mV/decade for Ce（Ⅳ） ion over a linear concentration range of 1×10^（–5）–1×10^（–1） mol/L with the detection limit of 9.0×10^（-6） mol/L. The electrode showed stable response within the SO_4^（2–） concentration range of 0.1–1 mol/L and the acidity range of 0.25–1.2 mol/L H＋. The proposed electrode showed high selectivity for Ce（Ⅳ） over a wide variety of interfering ions and a fast response time. It was used as an indicator in the potentiometric titration of Ce（Ⅳ） solution with H_2O_2 solution, and could also be used for the determination of Ce（Ⅳ） in real Ce（Ⅳ）-containing aqueous samples.

Electrochemical Detection of the Different Species of Levofloxacin Using PVC,Carbon Paste and Screen‑Printed Electrodes:Effect of pH

The zwitterionic compound,levofloxacin,was determined for the first time at different pH values in pure samples,pharmaceutical preparations and spiked serum and urine samples.Different types of potentiometric sensors including poly(vinyl chloride)membrane electrode,carbon paste electrode and screen printed electrode,containing the ion pair levofloxaciniumphosphomolybdate as the electroactaive species,were used for this purpose.The effect of pH is the key factor in determining the ratio of the different species that can exist in the medium(zwitterionic,monocationic,dicationic,anionic and neutral),and so it is the controller of the electrochemical performance.The different sensors were fully characterized and optimized in terms of composition,pH effect,selectivity,response and lifetimes.The different sensors showed reliable reversibility and could be utilized for the determination of the drug in real spiked physiological fluids with reliable recovery values.

Development of new potentiometric sensors for the determination of proguanil hydrochloride in serum and urine

Potentiometric electrodes were developed for the rapid determination of proguanil hydrochloride in pure samples, pharmaceutical preparations and spiked serum and urine samples using PVC membrane,screen printed（SPE）, coated wired（CWE）, carbon paste（CPE） and modified carbon paste（MCPE）electrodes based on the ion-exchanger of proguanil with phosphotungestic acid（Pr-PT） as a chemical modifier. The prepared electrodes showed Nernestian slopes of 59.7, 58.1, 58.5, 58.5 and 57.0 for the PVC,SPE, CWE, CPE and MCPE for the proguanil ions in a wide concentration range of 1.0 ＊ 10^-5–1.0 ＊ 10^-2mol L^-1 at 25°C with detection limits of 7.94 ＊ 10^-6, 1.0 ＊ 10^-5, 1.0 ＊ 10^-6, 7.07 ＊ 10^-6 and 2.5 ＊ 10^-6 mol L^-1, respectively. The prepared electrodes exhibited high proguanil selectivity in relation to several inorganic ions and sugars and they could be successfully utilized for its determination in pure solutions, pharmaceutical preparations and serum and urine samples using the direct potentiometry and standard addition methods with very good recovery values.

Quantitative Analysis of Holmium Ion by a Ho^3＋ Ion-Selective Sensor Based on a Symmetric Thio-Schiff＇s Base

A poly（vinyl chloride） （PVC） membrane sensor for holmium ions was fabricated based on N-[（Z）-l-（2-thienyl）- methylidene]-N-[4-（4-{[（Z）-l-（2-thienyl）methylidene]amino} phenoxy）phenyl] amine （TPA） as a new ion carrier, acetophenon （AP） as plasticizing solvent mediator and sodium tetraphenyl borate （NaTPB） as an anion excluder. The electrode shows a good selectivity towards Ho^3＋ ions respect to other inorganic cations, including alkali, alka- line earth, transition and heavy metal ions. The constructed sensor displays a Nernstian behavior （19.5±0.3 mV/decade） over the concentration range of 1.0× 10^-6 to 1.0 ×10^- 2 mol·L^-1 with the detection limit of the electrode being 4.6）〈 10-7 mol·L^-1 and very short response time （ca. 5 s）. It has a useful working pH range of 3.2-9.8 for at least 8 weeks. The electrode was successfully applied as an indicator electrode for the potentiometric titration of a Ho^3＋ solution with EDTA and holmium determination in some alloys. The proposed sensor accuracy was studied by the determination of Ho^3＋ in mixtures of three different ions.

Thiocyanate ion selective electrode based on bis(N-3-methylphenyl salicylidenaminato)copper(Ⅱ) ionophore

In this work a PVC membrane electrode based on bis（N-3-methyl phenyl salicylidenaminato）copper（II）as ionophore was prepared.The electrode was tested by inorganic anions and showed good selectivity for thiocyanate ion.This sensor showed Nerstian behavior with a slope of a-59.3 mV per decade at 25℃.The proposed electrode exhibited a wide linear range from 1.0 × 10^-6 mol/L to 1.0× 10^-1 mol/L with a detection limit of 5.0×10^-7 mol/L.The electrode response was independent of pH in the range of 4.0-10.0.The response time is about 9-21s,and the electrode can be used for over 60 days without considerable deterioration.The prepared sensor was applied as an indicator electrode in potentiometric titration of SCN^- with Ag^＋ ion and to determine the thiocyanate in samples of urine and saliva.