Tetracycline selective electrode based on molecularly imprinted polymer particles

Tetracycline selective electrode using molecularly imprinted polymer particles as quasi-ionophore was constructed the first time, and its performance was carefully characterized. Due to the specific recognition of tetracycline by the particles, the selectivity coefficients for routine interferences were less than 10-4. Benefited from the absence of tetracycline in the sensitive membrane and the optimized composition of the inner filling solution, the limit of detection of the electrode was reduced to about 2.5 × 10^-8 mol/ L. It exhibited a good electrode slope 57.6 mV/decade near the theoretical Nernstian one, with a wide linear working range from 6.0 × 10^-8 to 1.0 × 10^-3 mol/L. The fabricated electrode should be used in pH 2--4, response time of which was less than 200 s when the concentration of tetracycline was higher than 1.0 × 10^-6 mol/L and no more than 30 min at the concentration of 1.0 × 10^-8 mol/L.

Determination of Boron Trifluoride in Boron Trifluoride Complex by Fluoride Ion Selective Electrode

A method was proposed to determine boron trifluoride in boron trifluoride complex using fluoride ion selective electrode(ISE). Hydroxide was chosen to mask aluminum for the determination of 0.01—0.1 mol/L of fluoride. The simulation indicated that the permissible aluminum masked at a certain p H value was limited and hardly related to F-concentration and boric acid. It is better to control p H value below 11.5 and the aluminum concentration within 0.025 mol/L to minimize the interference of hydroxide to the fluoride ISE. The decomposition conditions of boron trifluoride by aluminum chloride were investigated. It is found that the F-detection ratio will approach 1.0 if the Al/F molar ratio is 0.3—0.7 and aluminum concentration is no more than 0.02 mol/L when heated at 80 ℃ for 10 min. In one word, hydroxide is quite fit to mask aluminum for samples which contain high content of fluoride and aluminum and the BF3 content can be successfully determined by this method.

A Method of Determining Selectivity Coefficients Based on the Practical Slope of Ion Selective Electrodes

It is a problem to be solved that the experimental selectivity coefficients of ion selective electrodes (ISEs) depend on the activity. This paper studied the new method of determining selectivity coefficients. A mixed ion response equation, which was similar to Nicolsky-Eisenman (N-E) equation recommended by IUPAC, was proposed. The equation includes the practical response slope of ISEs to the primary ion and the interfering ion. The selectivity coefficient was defined by the equation instead of the N-E equation. The experimental part of the method is similar to that based on the N-E equation. The values of selectivity coefficients obtained with this method do not depend on the activity whether the electrodes exhibit the Nernst response or non-Nernst response. The feasibility of the new method is illustrated experimentally.

Molecular Design of Crown Ethers. 19~1. Synthesis of Novel Disulfide and Diselenide-Bridged Bis (benzo-12-crown-4)s and their Ag^+ Selective Electrode Properties

Two novel heteroatom-bridged his (benzo-12-crown-4 ether)s, i.e. his [2-nitro-4,5 (1,4,7,10-tetraoxadecamethylene) disulfide 1 and diselenide 2, have been synthesized. X ray crystallographic structure was obtained for 1. Ion selective electrodes (ISE) for Ag+, containing 1 and 2 in PVC membrane as neutral carriers, were prepared, and their selectivity coefficients for Ag^+ (K_(Ag.M)^(pot)) were determined against other heavy metal ions, alkali and alkaline-earth metal ions. and ammonium ion. These ISEs showed excellent Ag^+ selectivities, log K_(Ag.M)^(pot) ≤ -3.8, against most of the interfering canons examined, except for Hg^+.

Effect of Preparation Process of Functional Polymer Active Materials on Properties of Gadolinium Ion Selective Electrode

Recently we have studied the rare earth ion-selective electrodes with active materials of the func-tional polymers and found that the process chosen for the functional polymers had an effect on the propertiesof gadolinium ion selective electrode besides the effects of their structures.1.Effect of preparation process of the grafted polymers on the properties ofgadolinium ion selective electrodesThe electrode membranes which consist of functional polymers as active materials were prepared by re-action of gadolinium chloride with the radiation grafted clmer of acrlic acid and polystyrene of which

A Method of Preparation of Ag/AgCl Chloride Selective Electrode

We put forward a method of rapid preparation of chloride selective electrode（Ag/AgCl electrode） by dipping silver wire into sodium hypochlorite solution. The electrodes were prepared through different immersion time. The properties of the electrodes, such as Nernst response, response time and longterm stability, were tested in simulated concrete pore solutions（SCPS）. Moreover, the surface morphology of the electrodes was also detected after immersion in solutions over three months. The experimental results reveal that the Ag/AgCl electrode with the fabrication time of 20 minutes（E-20） which is recommended to work as the chloride ion selective electrode has the best performance. Compared to that fabricated by the electrolytic process（E-EP）, E-20 can be manufactured in mass. The method has almost the same good performance of Nernst response as E-EP, and has a better response time which is less than 25 seconds. The method also shows a better good long-term stability in SCPS containing chloride ions over three months.

EFFECT OF STRUCTURE OF FUNCTIONAL POLYMER ACTIVE MATERIALS ON PROPERTIES OF GADOLINIUM ION SELECTIVE ELECTRODE

In this paper,the functional polymeric active materials were prepared by the grafting copolymerization and their structure and properties were studied.The results show that the structure and properties of these ac- tive materials have the relative large effects on the properties of gadolinium ion selective electrodes.

DETERMINATION OF SERUM ALBUMIN USING A SILVER ION SELECTIVE ELECTRODE

In this paper is reported a new method of determining serum albumin with potentiometry. The silver ion selective electrode was used as working electrode and S. C. E as reference electrode. By controlling the ionic strength, PH and temperature constant, a good linear relationship was obtained between the cell potential and albumin concentration. This method .possessed characters-of operating simplicity, rapidity and directness. The samples could be detected directly and the results were in accordance with the values detected by classic K method.

Determination of Fluoride in Various Samples Using a Fluoride Selective Electrode

Fluoride is widespread in the environment, water, air, vegetation and Earth’s crust which can entre ground and surface water by natural process. Fluoride in minute quantities is essential component for human health and help in normal mineralization of bone and formation of dental enamel. The determination of fluoride in some species was performed by using fluoride ion-selective electrode by direct measurement and standard addition method. The concentration of fluoride ion was determined in drinking water (from different place at Kathmandu), toothpaste, various brand of tea and coffees. The range of fluoride concentration in water sample was 0.16 to 0.39 mg/l, tea and coffee samples were 0.011 to 0.084 mg/l and its value of toothpaste was 0.026 to 0.75 mg/l. The concentration of fluoride ion obtain from different sample was compared with the legitimate value given by the world health organization.

Ion Selective Electrode Determination of Ammonia Nitrogen in Passaic River Waste Water in New Jersey Essex County Area

The percent ammonia nitrogen was determined in Passaic River waste water using Ion-Selective Electrode EPA Method 350.3. The intelligent ammonia sensor integrates ammonia electrode, pH electrode and Ammonia Ion electrode together to realize the in situ detection of ammonia. The test results have shown that the sensor is easy operation, low cost and no pollution. The ammonia is determined potentiometrically using an ammonia ion selective electrode and a pH/mV meter, having an expanded millivolt scale. The ammonia selective electrode uses a hydrophobic gas-permeable membrane to separate the sample solution from an electrode internal solution of ammonium chloride. Dissolved ammonia is converted to NH3 gas by raising the pH to above 11.0 with a strong base. NH3 gas diffuses the membrane and changes the internal solution pH that is sensed by the electrode. In single laboratory test results have been found 1.001 NH3-/L and 0.897 mg NH3-N/L, recoveries were 77.3% and 83.1%, respectively.

Preparation of New Uric Acid Sensors Based on Iodide Selective Electrode

An electrode for uric acid has been prepared by using an iodide selective electrode with the uricase enzyme. The iodide selective electrode used was prepared from 10% TDMAI and PVC according to our previous study. The enzyme was immobilized on the iodide electrode by holding it at pH 7 phosphate buffer for 20 min at room temperature. The H2O2 formed from the reaction of uric acid was determined from the decrease of iodide concentration that was present in the reaction cell. The potential change was linear in the 2 × 10-5 to 2 × 10-4 M uric acid concentration (3 - 34 mg uric acid/100ml blood) range. Uric acid contents of some blood samples were determined with the new electrode and consistency was obtained with a colorimetric method. The effects of pH, iodide concentration, the amount of enzyme immobilized and the operating temperature were studied. No interference of ascorbic acid, glucose and urea was observed.

A New Type of Dibenzoyl Tartaric Acid Selective Electrode Based on Polymer Membrane Containing Calixarene Ionophore

A new type of di benzoyl tartaric acid selective electr ode has been developed. Three double\| arm calixarene derivatives were emp loyed as the neutral ionophores. The poly(vinyl chloride) membrane electrode containing an amide derivative of ca lixarene as the neutral carrier an d a dibutyl phthalate as the plastici zer exhibited the highest sensitivity for dibenzoyl tartaric acid. The slop e of linear portion was 27.8 mV per c oncertration decade. The electrode has a fast response and a long lifetime .

Study on the Multi-Sensing System Based on the Tin Oxide pH Electrode

In this study,the multi-sensing system based on the tin oxide pH electrode for the ion-determination was presented. With the advantages of the real-time supervisory control apparatus,the measured values could be displayed on the liquid crystal display (LCD) immediately.In this study,the basic sensor was the tin oxide pH electrode,which was fabricated by radio frequency (r.f.) sputtering system on the indium tin oxide (ITO)/glass substrate.Moreover,the major blocks of the system consist of the tin oxide electrode-based ion selective electrodes (ISEs),an analog front-ended readout circuit,a microcontroller with built-in analog to digital (A/D) converter.In addition,by the embedded system design,the measurement results can be transmitted to a portable system or computer through the Universal Serial Bus (USB) and Universal Asynchronous Receiver Transmitter (UART) interface immediately.According to the experimental results,the multi-sensing system has high performance and reliability for pH,K^+,and Na^+ detection.

Free cupric ions in contaminated agricultural soils around a copper mine in eastern Nanjing City, China

To determine the environmental free metal ion activity was a recent hot issue. A method to measure low-level free cupric ion activity in soil solution extracted with 0.01 mol/L KNO3 was developed by using cupric ion-selective electrode （ISE） and calibrating with Cu-buffer solution. Three copper buffers including iminodiacetic acid （IDA）, ethylenediamine （EN）, and glycine （Gly） were compared for calibrating the Cu-ISE curves in the range of free cupric ions （pCu^2＋） 7-13. The Cu-EN buffer showed the best electrode response and thus was applied as the calibration buffer. The pCu^2＋ of 39 contaminated agricultural soils around a copper mine was measured, ranging from 5.03 to 9.20. Most Cu in the soil solutions was found to be complexed with dissolved soil organic matters, averaging 98.1%. The proportion of free Cu^2＋ ions in the soil solutions decreased with the increasing of solution pH. Soluble Cu and free Cu^2＋ ions concentrations were analyzed by multiple linear regressions to evaluate the effects of soil properties on metal levels and speciation. The results showed that soil solution pH was the most significant factor influencing pCu^2＋ （with R^2 value of 0.76）, while not important for the soluble Cu concentration.

Porous Silicon as a Carrier of Sensing Materials in Sensors

Novel potassium ion selective electrodes (K^+ISEs) and cDNA array sensors based on porous silicon (PS) have been developed.The calibration curve for the K^+ISEs is linear within a wide range of pK=2.0～6.0 with the slope of 56 mV per decade,which is near Nernst response.The response time and detection limit are within 31 s and 0.5μmol/L,respectively.The selective coefficient for Na^+ is-3.8,satisfies the requirement for the assay of blood potassium.The response variation is within 2 mV during 2 months.The binding capacity,the dynamic range and the detection limit of the DNA sensors were improved by replacing glass slide with PS substrates.The cDNA array sensors can bear 80℃of high temperature,75% of humidity,3.6 kLx of irradiation and keep stable within 10 days when they are exposed in air.Good performances of the K^+ISE and the cDNA array sensor are attributed to the large internal surface area and the easily modified microstructure of PS.

Recent progress on electro-sorption technology for lithium recovery from aqueous sources

Lithium is known as the“white petroleum”of the electrification era,and the global demand for lithium grows rapidly with the quick development of new energy industry.The aqueous solutions,such as salt lake brine,underground brine,and seawater,have large lithium reserves,thus this kind of lithium resource has become a research hotspot recently.Compared with other lithium extraction technologies,electro-sorption method shows good prospects for practical applications with advantages in the aspects of efficiency,recovery ratio,cost,and environment.Herein,this review covers recent progress on electro-sorption technology for lithium recovery from aqueous solutions,including the concept illustration,research progress of the applied working electrodes and counter electrodes,and the evaluation indicators of electro-sorption system.Meanwhile,some prospects for the development of this technology are also proposed.We hope this review is beneficial for the construction of high-efficient electrochemical lithium recovery system to achieve an adequate lithium supply in the future.

Design of Neutral Carrier for Solvent Polymeric Membrane Iodide Electrode With High Selectivity

Anion-selective electrodes based on dissociated ion-exchangers such as lipophilicquaternary ammonium or phosphonium species always display classical Hofmeister be-havior in the following order: ClO4-】SCN-】I-】Br-】NO2-】Cl-】SO42-.A new sol-vent polymeric membrane electrode based on Schiff base complexes of Co（Ⅱ）[Co（Ⅱ）S]and showing excellent selectivity toward iodide ion is for the first time prepared inour work. The resulting electrodes exhibit fairly low detection limits andpotentiometric anion-selectivity sequences deviated from the Hofmeister pattern.Bis（salicylaldehyde） ethylenediiminecobalt（Ⅱ） [Co（Ⅱ）（salen）], bis（salicylaldehyde）-phenyldiiminecobalt（Ⅱ） [Co（Ⅱ）（salophen）],

Mean Activity Coefficients of KCI in the KCI-K2B4O7-H2O Ternary System at 308.15 K by EMF Method

The mean activity coefficients of KCI in a KCI-K2B407-H20 ternary system were experimentally determined at 308.15 K by the electromotive force measurement（EMF） via a battery cell without a liquid junction： K-ISEIKCI（m1）, K2B4O7（m2）ICI-ISE（ISE=ion selective electrode） in a total ionic strength of from 0.01 mol/kg to 1.00 mol/kg at different ionic strength fractions of KzB407 with yB=0, 0.200, 0.400, 0.600 and 0.800. K-ISE and CI-ISE presented a good Nernst effect, which implies that this method could be used to measure the activity coefficients of an electrolyte in the above system. The Harned rule was fitted to the experimental data, the Harned coefficients and the Pitzer single-salt ion parameters of KC1 were evaluated, and the relationship diagrams between the mean activity coefficient of KC1 and the ionic strength fraction（yB） were drawn. The mean activity coefficients of KCI（γ±KCI） decreased monotonically with the increase of I. The experimental results obeyed the Harned rule well.

Novel potentiometric application for the determination of amprolium HCl in its single and combined dosage form and in chicken liver

Three novel amprolium HCl（AMP）-selective electrodes were investigated with 2-nitrophenyl octylether as a plasticiser in a polymeric matrix of polyvinyl chloride（PVC）. Sensor I was fabricated using potassium tetrakis（4-chlorophenyl） borate（Tp ClPB） as a cationic exchanger without incorporation of an ionophore.Sensor Ⅱ used 2-hydroxy propyl β-cyclodextrin as an ionophore while sensor Ⅲ used p-tert-butylcalix[8]arene as an ionophore. The three proposed sensors showed Nernestian response slopes of 29.2±0.8,29.3±0.6 and 30.2±0.4 m V/decade over the concentration range from 10–6 to 10–2 mol L_（-1）,respectively. The proposed sensors displayed useful analytical characteristics for the determination of AMP in bulk powder, different pharmaceutical formulations, and chicken liver and in the presence of ethopabate. The proposed method was validated according to ICH guidelines for its linearity, accuracy,precision and robustness.