El método de Mohr se emplea para la determinación de cloruros en . ¿Cuál será la concentración en equilibrio de los iones de plata en mg/L, con. Métodos instrumentales para la determinación de NaCl en las salmueras de de iones cloruro o sodio, para la determinación de la concentración de NaCl en las encuentran desplazados en relación al obtenido por el método de Volhard. Determinación de cloruros por los métodos de Mohr y Volhard. Sara Isabel Bonilla Hernández. Valentina Betancur Agudelo. VOLUMETRÍA. Encontrar la.
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Construction and evaluation of chloride ion-selective electrodes. The constructed electrodes showed a fast potentiometric response to chloride in the concentration range from 0 -6 to 10 -2 mol. The accurate determination of low levels of the chloride ion is essential, according to its important biological relevance . As an example, chloride is an essential component of the human diet, being the minimal request for adults of mg day.
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Besides, this ion plays an important role in the regulation of extra-cellular fluids and variations in its concentration in biological fluids are often associated to different abnormal metabolic processes and diseases .
Different methodologies have been reported for the determination of the chloride ion. These include chromatographic, spectrophotometric, voltmetric, turbid metric and volumetric methods such as the classical Volhard titration . Although several methodologies have become standard in the field for chloride determination, many of them suffer from important disadvantages, in particular due to the need of large analysis times and tedious sample pre-treatments.
The use of selective electrodes represents an alternative method for the potentiometric determination of different species; allows reducing some of the drawbacks associated with the chloride ion analysis by other methodologies . In the last few yearsthe construction of robust electrochemical sensors, sensitive and precise, capable of detecting and quantifying the concentration of different substances in a variety of solutions including biological fluids and direct samples from ecosystems has been a subject of much interest.
Ion-selective electrodes ISE are very appropriate for dloruros purpose because they are easy to build, the results are obtained quickly, they show good selectivity for inorganic ions, they are of relatively low cost and dloruros are portable and easily handled determinaciln they can be used in the places of interest.
All the reagents used in this study were of analytical grade. Polyvinylchloride PVC from Aldrich was directly used as received as the polymeric matrix, employing Araldite Ceys mixing of A and B components for the grafting. The elemental analyses were carried out using a Carlo-Erba Ea Elemental Analyzer and melting points were determined with a Buchi melting point apparatus.
The composition of the prepared membranes was as follows: The mixture was dissolved in 3 mL of dry THF.
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The resulting membrane cocktail was then deposited on a previously formed 1: Determination of the electromotive force EMF. The electromotive force EMF determinations were carried out by using an open cell to ambient temperature.
This was done following the Nernst law through data adjustment by a linear regression method. The selectivity coefficients K AB Pot were determined in the presence of various foreign ions by using the method of mixed solutions  2. Synthesis of 2- 5- 4-nitrophenyl furyl -4, 5-diphenyl imidazole. The synthesis of 2- 5- 4-nitrophenyl furyl -4, 5-diphenyl imidazole FFDFIN was carried out from 5- 4-nitrophenyl furfural and benzyl in the presence of ammonium acetate and glacial acetic acid.
The reaction between benzyl I and 5- 4-nitrophenyl furfural II was carried out by adding 1,94 g 0, 2 mol of I to 2 g 0, 2 mol of II and in the presence of 14 g 0,2 mol of ammonium acetate. Glacial acetic acid 40 mL was used as solvent.
The reaction mixture was heated for 5 h at reflux temperature and then 25 mL of distilled water was added. The crude product was then filtered and washed with water followed by dissolution in mL of water.
The different analyses carried out on this compound were in good agreement with the formation of the expected structure. Thus, the FT-IR spectrum showed the presence of the N-H absorption bands at 3 cm -1 along with absorption bands at 1 cm -1 region corresponding to the aromatic fragments. The presence of the nitro group was confirmed by existing of the absorption bands at 1 and 1 cm The 1 H NMR of FFDFIN showed the presence of the expected signals at 7,6 ppm for the phenyl groups at C4 and C5 of the imidazole group, at 8,4 ppm for the 4-nitrophenyl group located at C2 of the imidazole and at 6,5 ppm for the imidazole N-H and for the hydrogen atoms at the furan ring.
The elemental analysis of the salt gave: Electrode preparation and characterization.
After optimization of the conditions of use, experimental data revealed that this kind of electrodes were highly selective to the chloride ion relative to several other ions figure 1. In general, the characteristics and properties of an ion-selective electrode, i.
In this regard, we studied the influence of the different coruros assayed for the membranes on their properties. The characteristic parameters of the optimized membranes are summarized in metoco 1.
The response of the electrodes prepared with different amounts eeterminacion plasticizers and ionophores was studied providing some clear trends.
In all cases studied, the electrodes showed Nernstian slope per decade for chloride activity in wide range of the activity studied, showing detection limits in the order of 10 -6 -2 mol. The detection limit decreases considerably with the lifetime. The effect of the pH of the test solutions on the response of the sensor was studied using different solutions being 1.
In order to carry out properly this study, it is important avoiding simple combined pH electrodes. A second aspect to be considered is the variation in the potential at the liquid union between the reference and the working solution. This variation can occur, in particular, at low pH because of the high mobility of the hydronium ion and can be minimized if the nature of the ionic species present in solution does not experiment significant variations.
According to this, H 2 SO 4 was selected for the acidification of clorurso medium taking into consideration that the sulphate anion is present in the reference electrode, while NaOH was selected as the base for the basification of the medium.
In this way, the variation in the liquid union potential can be essentially attributed to the differences in concentrations, but not to the existence of different species in the solution.
The responses in the values for the potential indicated that no significant changes take mefodo within the pH range In order to determine the deterjinacion potential for the analytical application of this ISE, the possible interference by different anions was studied by using the method of mixed solutions .
The static response time obtained was moohr than 30 seconds.
Preliminary analytical application of the sensor. An example of the resulting titration curves is shown in figure 4. As can be seen, the amount of silver ions in solution could be determined with the electrode. A new ion-selective electrode formed by a polymeric liquid membrane and by using 2- 5- 4-nitrophenyl furyl -4,5-diphenyl imidazole FFDFIN as ionophore, DOS as plasticizer and PVC as matrix, sensible to chloride ion can be considered highly reproducible.
The results obtained permitted the utilization of the constructed ion-selective electrode for precise determination of chloride. Here we report the use of 2- 5- 4-nitrophenyl furyl -4, 5-diphenyl imidazole, a highly selective carrier for the building of ISE devices for the detection of the chloride ion using a PVC membrane with bis 2-ethylhexyl sebacate DOS as the plasticizer.
The electrodes were conditioned in 1. The electrochemical cell used was: In order to achieve a detailed study of the response of the electrodes to the chloride anion, the corresponding calibration curves were obtained figure 2. These calibration curves were used to calculate the essential parameters such as slope Cloruroapractical detection limit PDL and lower limit of linear response LLLR.
This was done through data fitting using a linear regression method following the Nernst law. As can be seen in table monrthe selectivity coefficients range at about 10 -2indicating they most significantly disturb the functioning of the chloride selective membrane.
The lifetime of the sensor is also an important parameter to assess its practical applicability. After these periods of time, the electrochemical behaviors meetodo the sensors gradually deteriorate.
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Log K AB Pot.