Potentiometric Determination Of Chloride Research Articles

Determination of the selectivity coefficient of a chloride ion selective electrode in alkaline media simulating the cement paste pore solution

The measurement of the free chloride concentration in the pore solution of cement paste or concrete is of interest for assessing the probability of corrosion of the steel reinforcements embedded in concrete. This determination is performed through leaching or pore-pressing methods or through embedded potentiometric sensors into the hardened cementitious material. The potentiometric determination of chloride in cement paste pore solutions is limited by hydroxide ion interference, due to the high alkalinity of such media. The potentiometric selectivity coefficients, k Cl - , OH - , are determined for a chloride ionic selective electrode in alkaline solutions simulating the electrolyte present within the pore network of cement paste and concrete. This is done using a fixed interference methodology, with least-squares non-linear curve fitting for obtaining the selectivity coefficients together with other relevant electrode parameters. The limit of detection of the Cl − ISE, due to OH − interference, varies with pH. For the pore solution corresponding to an ordinary Portland cement paste or concrete, this limit can be set between 3 × 10 –3 m, and 7 × 10 –3 m, i.e., approximately below a chloride concentration value of 1 × 10 –2 molal. Taking into account these limits of detection the free Cl − concentrations able to depassivate the steel, can be adequately determined by potentiometric measurements with calibrated ISEs in the expressed pore solutions of Portland cement concretes, without significant influence of OH − interference. Nevertheless, this effect can prevent the adequate measurement of low free Cl − concentrations, below the corresponding limit of detection value.

Sample introduction in multi-syringe flow injection systems: comparison between time-based and volume-based strategies

In multi-syringe flow injection analysis (MSFIA), devices as selection, injection or commutation valves must be incorporated to the manifold to provide access to sample and standard solutions. Therefore, the definition of sample amount can be either volume or time-based. In the present work, four configurations for sample introduction (two for each approach) were tested in order to establish if the different strategies affect the analytical signal in MSFIA systems. The mean absorbance value from ten consecutive injections of a bromothymol blue solution obtained for the time-based strategy was lower than that provided by the volume-based approach as the exact volume delivered by each configuration was different from the “theoretical” volume. For time-based configurations, the exact volume delivered is 2–5% lower than the theoretical value while for volume-based configurations, the volume delivered was between 6 and 46% larger than the theoretical volume. Moreover, for time-based sampling, the order of steps in the analytical cycle was of utmost importance since any alteration in the flow direction affected the volume delivered in the subsequent step in the analytical cycle. The influence of the two sampling approaches was also evaluated in the MSFIA systems for the spectrophotometric determination of phenolic compounds and the potentiometric determination of chloride. There was no evidence that the use of either volume or time-based sampling would improve the analytical features of these determinations when real samples were tested.

Simultaneous assay of nitrite, nitrate and chloride in meat products by flow injection.

A flow injection (FI) analytical method for the simultaneous assay of nitrite, nitrate and chloride in meat products is reported. The method is based on the potentiometric determination of chloride using a tubular ISE and on the spectrophotometric determination of nitrite. The FI system consisted in splitting the flow after potentiometric detection using a tubular detector and the subsequent confluence of the flow before reaching the spectrophotometric detector. This allowed the reduction of nitrate to nitrite in part of the sample plug on an on-line copper cadmium reductor column. Since each channel had a different residence time, two peaks were obtained for nitrite and nitrite plus nitrate. Spectrophotometric determination was made after a diazotization-coupling reaction. The results obtained were in good agreement with reference procedures and showed adequate precision (RSDs less than 6% for chloride and nitrite and 2% for nitrate). A high sampling rate was obtained (120 determinations per hour corresponding to 40 samples per hour).

Studies on the elimination of sulfide interference in the potentiometric determination of chloride using ion selective electrodes in a flow injection system

Detailed investigations have been reported on the application of a common procedure using bromate in nitric acid for the removal of the interference of sulfide in the direct potentiometric determination of chloride using silver-based ion selective electrodes in a flow injection system. It is shown that this procedure is not very efficient and carries a high risk of chloride underestimation. With increasing levels of sulfide the oxidation of chloride to elemental chlorine becomes progressively significant and under certain circumstances virtually no chloride is left irrespective of its initial concentration. Hydrogen peroxide in alkaline medium is proposed as a suitable alternative for the efficient removal of sulfide without any adverse effects on the potentiometric method.

Oxidative removal of interferences in flow-injection potentiometric determination of chloride

Direct potentiometric determination of chloride in a flow-injection system can be performed in the presence of excess bromide, iodide, sulphide and cyanide, when potassium bromate in nitric acid is used as the carrier solution. The hydrodynamics and temperature of such a system have been examined and various oxidants and indicating electrodes investigated. The analysis can be performed at a maximum rate of 120 samples per hour.

Reference electrodes for use in the potentiometric determination of chloride. Part III. Chloranil electrodes

Reference electrodes consisting of platinum electrodes immersed in solutions of constant pH saturated with tetrachlorobenzoquinone and tetrachlorohydroquinone have been tested for use in the potentiometric determination of chloride. The composition of the solution inside the reference electrode is matched with the main components of the treated sample solution (i.e., after addition of reagents to control pH and ionic strength but excluding chloride itself). In this way the effect of the liquid junction potential is minimised. The electrodes have a sealed construction, need no maintenance and can be used immediately on assembly.

Reference electrodes for use in the potentiometric determination of chloride. Part I. Assessment of mercury-mercury(I) sulphate electrodes

Mercury-mercury(I) sulphate reference electrodes are used in the potentiometric determination of chloride. There have been various reports of their erratic behaviour, which is especially serious because chloride-selective electrodes are often working at the limits of their sensitivity in highly pure waters, such as condensed steam and boiler water. The loss of precision in e.m.f. in such circumstances has a much larger effect on the precision in concentration terms than when electrodes are working in their usual (Nernstian) sensitivity range. Commercial mercury-mercury(I) sulphate electrodes have been tested over several weeks of continuous operation so that their performance can be assessed when used under conditions similar to those of chloride monitoring, i.e., in pH 4.4 acetate buffer solution with silver chloride electrodes and 0.01 mol l–1 nitric acid solution with mercury(I) chloride electrodes. Electrodes were obtained from two manufacturers and were of two types—one with ground-glass sleeve liquid junctions and one with a ceramic-frit junction. The latter was the best of those tested. The rate of change of its potential with respect to a calomel electrode was less than 0.5 mV over 100 h and the standard deviation of its potential over a week's operation was about 0.3–0.5 mV. Deviations of potential previously reported with this type of electrode could not be reproduced in this work. Some electrodes with ground-glass sleeve junctions became erratic after 2–4 d in the nitric acid solution normally used with mercury(I) chloride sensing electrodes. Their performance was better in the acetate buffer medium used with silver chloride sensing electrodes but inferior to that of similar electrodes with ceramic frit junctions.

Reference electrodes for use in the potentiometric determination of chloride. Part II. Quinhydrone electrodes

Download options Please wait... Article information DOI https://doi.org/10.1039/AN9840900445 Article type Paper Download Citation Analyst, 1984,109, 445-452 BibTex EndNote MEDLINE ProCite ReferenceManager RefWorks RIS Permissions Request permissions Reference electrodes for use in the potentiometric determination of chloride. Part II. Quinhydrone electrodes D. Midgley, Analyst, 1984, 109, 445 DOI: 10.1039/AN9840900445 To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page. If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given. If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page. Read more about how to correctly acknowledge RSC content. Social activity Tweet Share Search articles by author Derek Midgley

Interference measurements in the potentiometric determination of chloride at ppb level using an ion-selective electrode

Detailed investigations on the interference of Br −, I −, S 2− and nitrogen-based pH adjustors over the chloride estimations at ppb level were carried out by differential potential measurement technique using an ion-selective electrode. The trend in the limiting interference concentrations were found to be not in accordance with the solubility product considerations alone. The presence of excess free amine/ammonia affected the stability of the measurement because of possible formation of the Ag—amine complex. The slope of the chloride calibration ranged from 0.01 to 0.015 mV per ppb, depending upon the medium.

Potentiometric determination of chloride and bromide in airborne dust

A simple, rapid and reproducible potentiometric titration method for determination of both bromide and chloride in airborne dust is described. The use of a precise microburette and a differentiating recorder allows good resolution of the two species determined. The method can be easily applied for routine environmental control analysis.

Potentiometric determination of chloride in inorganic orthophosphates in citrate-buffered media

The chloride content of some inorganic orthophosphates and phosphate rock samples has been determined in a medium buffered to pH 2·5 with a mixture of perchloric acid, citric acid and trisodium citrate. The method has been compared with an earlier method which employed a mixture of perchloric acid, citric acid and triethanolamine. The present method is of similar reproducibility and does not suffer from decomposition of the reagents. The interference patterns of several metals are discussed.

Potentiometric determination of chloride in biological fluids.

Potentiometric determination of chloride in biological fluids.

Attempts at the potentiometric determination of chloride in biological fluids with the silver-silver chloride electrode

Download options Please wait... Article information DOI https://doi.org/10.1039/AN9507500679 Article type Paper Download Citation Analyst, 1950,75, 679-684 BibTex EndNote MEDLINE ProCite ReferenceManager RefWorks RIS Permissions Request permissions Attempts at the potentiometric determination of chloride in biological fluids with the silver-silver chloride electrode McD. Duxbury, Analyst, 1950, 75, 679 DOI: 10.1039/AN9507500679 To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page. If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given. If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page. Read more about how to correctly acknowledge RSC content. Social activity Tweet Share Search articles by author McD. Duxbury