Feasibility of Performing Concurrent Coulometric Titrations Using a Multicompartment Electrolysis Cell

Abstract

Feasibility of performing multiple coulometric titrations in a single course of electrolysis is presented. In these titrations, three pairs of cathode and anode compartments were connected with a network of electrodes and salt bridges. Passage of current through the cell caused concurrent electrolysis in cathode and anode compartments. Electrogenerated reagents produced in these compartments were used as titrants for quantifying the analyte samples. Endpoints of the titrations were determined from the visual color change of an indicator. The charge passing through the cell was monitored and Faraday’s laws of electrolysis were applied to assess the quantitative relation between the charge and analyte concentration. Experimentally determined coulombs required to titrate aqueous potassium hydrogen phthalate, MnO 4 – , OH – , and S 2 O 3 2– were 0.100, 0.466, 0.103, and 0.0934 C, respectively. These results matched with estimated values of 0.0965, 0.482, 0.0965, and 0.0965 C, respectively. Agreement between the coulombs determined from experimental results and reaction stoichiometry suggests a feasible application of concurrent coulometric titrations. Efficacy of the method was tested for determining the active ingredients in household vinegar and vitamin C dietary supplement tablets. Quantities of acetic acid and ascorbic acid in these products were 5.1% and 980 mg, respectively, agreeing with the quantities determined from volumetric titrations (5.1% and 990 mg) and manufacturer’s label (5.0% and 1000 mg).

Analytical Capabilities of Coulometric Sensor Systems in the Antioxidants Analysis

“…Taking into account the different strengths of the titrants-oxidants, there is the possibility of controlling the selectivity of the target analyte response. Thus, electrogenerated iodine does not oxidize phenolic AOs [55] and retinol [63], while it reacts with thiol-containing AOs [47][48][49][50][51] and ascorbic acid [55,59,60]. On the contrary, hexacyanoferrate(III) ions easily interact with phenolic AOs and ascorbic acid [55] but do not react with S-containing AOs.…”

Electrochemical Capture and Storage of CO2 as Calcium Carbonate

“…Therefore, we designed an alternative electrochemical method for the in situ production of OH − ions to facilitate Equations (2)–(4) and alleviate the need for NaOH. Electrochemistry is a powerful way to produce reactants on demand at the surface of an electrode [25] and in this instance OH − ions can be produced by reduction of water at the cathode [Eq. (6)]: …”

Coulometer from a Digitally Controlled Galvanostat with Photometric Endpoint Detection

“…The coulometric technique shows some important advantages over the classical titration methods such as high sensitivity, the usage of aa very low amount of reagent required, and/or unstable compounds as titration agents, no primary standard is needed and the main reactant (electrons) can be precisely controlled. Nevertheless, some drawbacks that can be overcome are also present such as a more complex instrumentation, the non-commercial availability of specific experimental devices, specific training for the laboratory specialist, and normally, a higher budget hardware [ 6 , 7 , 8 ].…”