University of North Florida
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Stuart Chalk, Ph.D.
Department of Chemistry
University of North Florida
Phone: 1-904-620-1938
Fax: 1-904-620-3535
Email: schalk@unf.edu
Website: @unf

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Electrode

Classification: Electrode -> ion selective -> iodide

Citations 21

"Flow Injection Potentiometric Determination Of Residual Chlorine In Water"
Anal. Chim. Acta 1982 Volume 136, Issue 1 Pages 85-92

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Marek Trojanowicz, Wojciech Matuszewski and Adam Hulanicki

Abstract: Residual chlorine is measured in water by using a potentiometric system composed of an iodide-selective electrode and a platinum electrode sensing the iodine-iodide ratio. When the sample is added to acidified iodide solution, the cell response is in a logarithmic relation to the iodine concentration which in turn depends on the concentration of residual chlorine. In the flow injection system evolved, 0.1-5.0 mg L-1 residual chlorine can be determined at a rate of 40-60 samples per hour. The results of potentiometric determinations of residual chlorine in tap water compared to spectrophotometric results suggest that the presence of various organic substances is responsible for discrepancies between these measurements.
Chlorine Environmental

"Sequential Flow Injection Determination Of Cyanide And Weak Metal Cyanide Complexes With Flow-through Heterogeneous Membrane Electrodes"
Anal. Chim. Acta 1988 Volume 215, Issue 1-2 Pages 283-288

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E. Figuerola, A. Florido, M. Aguilar and J. De Pablo, S. Alegret

Abstract: Two I--selective heterogeneous epoxy-based membrane flow-through electrodes were placed before and after a gas diffusion unit in a flow injection system for determination of free and total CN-. The CN--containing sample was injected into a KNO3 carrier solution and free CN- was determined by the first flow-through electrode. The solution was then treated with the HCl stream in the reaction coil. The HCN evolved passed through the gas-permeable membrane in the diffusion unit and was collected in an alkaline solution, where the CN- was measured by the second flow-through electrode. Under optimum conditions, the response was rectilinear from 10 µM to 1 mM CN- and the coefficient of variation were ~2% with a sampling rate of 20 h-1. Total CN- could be determined in the presence of Zn, Cu(II) and Cd but results were low in the presence of Ni, Co(II) and Fe(III). Sulfide and SCN- were not tolerated. The reproducibility was worse than that of spectrophotometric detection but the method could be used over a wider concentration. range and was more suitable for an online control monitoring system.
Cyanide Cyanide, complexes, metal Gas diffusion Interferences Optimization Indirect Method comparison

"Response Time Phenomena Of Coated Open-tubular Solid-state Silver Halide-selective Electrodes And Their Influence On Sample Dispersion In Flow Injection Analysis"
Anal. Chim. Acta 1992 Volume 261, Issue 1-2 Pages 381-390

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Jacobus F. van Staden

Abstract: A comparative study has been made of the response times of coated open-tubular Ag membrane electrodes selective towards Cl-, Br- or I- (cf. Ibid., 1986, 179, 407) as they affect the throughput of flow injection analysis systems. The tubular indicator electrodes were used in conjunction with an Orion 90-02 double-junction reference electrode with 10% KNO3 solution in its outer chamber. The digitized signals were smoothed by applying the DS (data sets) Cat and Smooth operations of the ASYST software; typical background-corrected graphs for the flow injection measurement of halides (10 to 5000 mg l-1) are reproduced. Examination of the leading edges of the various peaks showed that their rate of response was independent of concentration. and did not significantly decrease the sampling rate, although the response of the Br- electrode at the initial peak-formation stages near the baseline was slightly slower than that of the others. The rate of response of the trailing edges was mainly responsible for the sampling rate in an optimized flow injection system, and the I- electrode showed a memory effect, which was largely responsible for the low sampling rate of this system compared with similar systems with the other two electrodes. The contribution of the memory effect or response time phenomena of coated open-tubular solid state chloride-, bromide-, and iodide-selective electrodes on the anal. output in flow injection systems are presented for concentration. ranges between 10 and 5000 mg L-1. The rate of response for the leading edges of all three electrodes due to electrode properties are independent of concentration. and do not contribute significantly to any decrease in sampling rate, although the rate of response of the bromide-selective electrode flow injection analysis (FIA) system seems to be slightly slower than the other two electrode systems at the initial peak-formation stages near the base line. The rate of response for the tailing edges of the different electrodes due to electrode properties is mainly responsible for the sampling rate obtained in an optimized FIA-ISE system. The memory effect of the iodide-selective electrode is mainly responsible for the fact that the sampling rate of this system is very much lower than the sampling rate obtained for similar systems with the other two electrodes. For the bromide-selective electrode system, the slower rate of response due to electrode properties at the tailing edges (especially with high concentrations of bromide) than that of the chloride-selective electrode, contributes mainly to a lower sampling output for the bromide-selective electrode-FIA system when compared with the chloride electrode system.
Bromide Chloride Iodide Optimization Signal processing Dispersion

"Flow-through Tubular Iodide- And Bromide-selective Electrodes Based On Epoxy-resin Heterogeneous Membranes"
Talanta 1989 Volume 36, Issue 8 Pages 825-829

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S. Alegret*, A. Florido, J. L. F. C. Lima and A. A. S. C. Machado

Abstract: The electrodes were made from 4-mm lengths of Perspex tubing (1 cm o.d., 8 mm i.d.), which were filled with Ag-containing conductive epoxy-resin to which a shielded cable was then attached. A hole (1.75 mm diameter) was drilled through the centre, which was then packed with powdered AgX - Ag2S mixture (X = I or Br) dispersed in non-conductive epoxy-resin. A central channel (0.75 mm diameter) was then drilled leaving a membrane of 0.5-mm thickness. The response characteristics were evaluated in a low-dispersion flow injection system, and both showed a Nernstian response between 50 µM and 0.1 M with good reproducibility and a rapid response that permitted a sampling rate of 60 h-1. Operational pH ranges for I- and Br- were 2.5 to 11 and 3 to 10, respectively. Interference by several ions is reported; I- must be absent in determinations with the Br- electrode.
Iodide Bromide Interferences Membrane Resin Injection technique

"Simultaneous Determination Of Chloride, Bromide, Iodide And Fluoride With Flow Injection - Ion-selective Electrode Systems"
Talanta 1992 Volume 39, Issue 10 Pages 1259-1267

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Fadhil M. Najib* and Shireen Othman,

Abstract: Electrodes for Cl-, Br- and I- were constructed (preparation described) from Ag2 - AgCl or AgBr (1:1) and Ag2S - AgI (1:3); for F- a commercial electrode was used. By combining the electrodes and suppressor columns of AgCl and amalgamated Pb, the ions were simultaneously determined in a carrier stream (0.5 mL min-1) of e.g. 0.1 M HClO4 at pH 4.0. The calibration graphs were rectilinear down to 100, 5, 1 and 5 µM for Cl-, Br-, I- and F-, respectively. The reproducibility was 1% for the determination of the halides in eight water samples, the results agreed well with those obtained by three reference methods. Flow-through ion-selective electrodes were constructed from compressed pellets (8-10 mm thick, 13 mm diameter, 10 tons/cm2 pressure) of Ag2S/AgX (X = Cl-, Br- or I-) drilled longitudinally (1.5 mm diameter hole) to be suitable for use in flow injection analysis. A column of AgCl (5.5 cm long, 2-3 mm internal diameter) was included in the Cl- electrode manifold to remove interferences from 10^-4 M Br- and 3 x 10^-5 M I- and S2-. A column of amalgamated lead (2-3 cm long, 2-3 mm internal diameter) was used in the Br--electrode manifold to remove interference from 2 x 10^-5 M I-, 3 x 10^-5 M S2- and 7 x 10^-4 M Cl-. These columns and the addition of ascorbic acid were not required when I- was determined with the iodide electrode. The carrier stream was 0.1 M sodium perchlorate (pH 4) at a flow-rate of 0.5 mL/min. The sample pH could be 4-7. Simultaneous determination of Cl- and I-, Cl-, I- and Br-, and Cl-, I-, Br- and F- ions was possible with combinations of the corresponding electrodes and columns in series and/or parallel in specially designed manifolds. Calibration plots were linear, with almost theoretical slopes, down to 10^-6 M I-, 5 x 10^-6 M Br-, 10^-4 M Cl- and 5 x 10^-6 M F-, with precision better than 1%. Sampling rates for single-ion determinations were 72, 102, 90 and 80 per h for the one-, two-, three- and four-electrode systems respectively. Determinations of these ions in water samples by the recommended procedure and by established batch methods showed no significant difference at the 95% confidence limits in a paired comparison t-test.
Chloride Bromide Iodide Fluoride Environmental Method comparison pH Interferences

"Flow-through Units For Solid-state, Liquid And PVC Matrix Membrane Ion-selective Electrodes To Minimize Streaming Potentials"
Analyst 1987 Volume 112, Issue 9 Pages 1293-1298

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Theodore K. Christopoulos and Eleftherios P. Diamandis

Abstract: Three flow-through units were constructed (diagrams given) and evaluated for electrode membranes sensitive to iodide (solid), perchlorate (liquid) and propantheline (PVC matrix), respectively. Streaming potential oscillations were reduced to 0.2 mV by siting the sensing membrane as near as possible to the external reference electrolyte - sample solution contact zone. Air-segmented streams were used to study the effect of flow rates of 1.74, 3.64 and 6.7 mL min-1. Sampling rates of up to 60, 120 and 240 h-1, respectively, were achieved.
Iodide Perchlorate Propantheline Method comparison Segmented flow

"Effect Of Flow Injection Parameters On The Selectivity Of An Iodide-selective Electrode"
Analyst 1992 Volume 117, Issue 4 Pages 761-765

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David E. Davey, Dennis E. Mulcahy and Gregory R. O'Connell

Abstract: The effects of sample loop volume, flow rate, carrier I- concentration, interferents, solution pH and temperature were studied, with selectivity coefficient being measured for Br-, SCN- and thiosulfate. Samples of 100 µL should be mixed with a 1 µM-KI carrier and a 0.1 M KNO3 reagent stream flowing at a combined rate of 6 to 7 mL min-1 in either neutral or acid solution at 20°C. A study has been carried out on the influence of several experimental parameters on the selectivity of a homogeneous membrane iodide-selective electrode operating under flow injection conditions. Selectivity coefficients were measured for bromide, thiocyanate and thiosulfate by use of a mixed-solution technique, with the effects of sample loop volume, flow rate, carrier iodide concentration, interferent activity, solution pH and temperature being investigated in turn. When the flow system was optimized, it proved possible to double the selectivity of the electrode towards iodide. Facets of the observed behavior were found to correlate well with existing theories on the time-dependent response of solid-state ion-selective electrodes. Peak profiles were also examined, with particular attention being given to the potential excursions or 'overshoots' recorded when mixed solutions of low iodide activity were injected into the flow stream.
Iodide Selectivity Interferences Optimization

"Rapid-flow Continuous Analysis With Ion-selective Electrodes"
Anal. Chem. 1980 Volume 52, Issue 14 Pages 2403-2406

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Peter W. Alexander and Purneshwar Seegopaul

Abstract: A study of rapid sampling in a continuous-flow system is reported with an iodide solid-state electrode as a continuous sensor. The system is operated by consecutive manual aspiration of sample and wash solutions into a flow manifold with air segmentation to reduce carry-over. The design features and flow rates used in the operation of the system are described, and it is found that sampling rates up to 360/h are permissible with flow rates as low as 9.2 mL min-1. The concept of combining rapid flow with air segmentation is shown to give an Improved method for achieving rapid sampling with electrode detection in a continuous-flow system with advantages over the more complex bubble-gating and flow-injection techniques currently in use.
Iodide

"Incorporation Of A Coated Tubular Solid-state Iodide Selective Electrode Into The Conduits Of A Flow Injection System"
Fresenius J. Anal. Chem. 1986 Volume 325, Issue 3 Pages 247-251

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Jacobus F. van Staden

Abstract: A tubular flow-through electrode (5 mm long, 2 mm i.d.) prepared by depositing AgI on silver foil and connected to an Orion Research microprocessor Ionalyzer with an Orion double-junction reference electrode was incorporated in a flow injection system (diagram given) capable of 90 samples h-1. Samples and ionic-strength-adjustment buffer were fed by a peristaltic pump with a pulse suppression system. Optimum sensitivity and response were obtained with 0.1 M KNO3 - 0.02 M acetic acid buffer. Response of carefully conditioned electrodes was rectilinear from 5 to 5000 mg L-1 of I-; they were stable and needed little maintenance. Analyses of iodized table salt agreed reasonably with quoted I- concentration, with a coefficient of variation of <1.8% (n = 15). The practical range was 5 to 2000 mg l-1.
Iodide Iodized Apparatus Computer Optimization Pulse dampener Ionic strength Buffer

"Flow Injection Potentiometry For Low Level Measurements In The Presence Of Sensed Ion In The Carrier"
Fresenius J. Anal. Chem. 1987 Volume 328, Issue 8 Pages 653-656

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Marek Trojanowicz and Wolfgang Frenzel

Abstract: A theoretical treatment based on the Nikolski equation is presented for the response of ion-sensitive electrodes in flow injection analysis, and the predictions are compared with experimental results obtained with a F--selective electrode and 0.2 M NaCl - 0.2 M acetate buffer (pH 5.2) containing F- (100 µg l-1) as carrier and with an I--selective electrode and a carrier of 0.2 M KNO3 containing ascorbic acid (1 g l-1) and I- (100 µg l-1). Measurements were made in a single-line manifold with a variable length of tubing (0.8 mm i.d.) and an injected volume of 100 µL. Significant deviations due to slow response were observed, but it is possible to linearize the calibration graph for low-dispersion systems and the electrodes can be used, with limited sensitivity, in the µg L-1 concentration. range.
Fluoride Iodide Theory

"Effect Of Addition Of Main Ion To Carrier Solution In Potentiometric Flow Injection Measurements With Solid State Ion-selective Electrodes"
Fresenius J. Anal. Chem. 1987 Volume 328, Issue 1-2 Pages 27-32

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