G. Nagy

Application of silicone rubber-based graphite electrodes for continuous flow measurements : Part II. Voltammetric study of active substances injected into electrolyte streams

Abstract A technique has been developed for the rapid analysis of samples injected into a streaming supporting electrolyte in small volumes. At constant potential the peak area of the voltammetric signal is proportional to the amount of electroactive material injected. The parameters of the determination were studied and interpreted theoretically. The experimental results are in good agreement with theory.

A novel titration technique for the analysis of streamed samples—the triangle-programmed titration technique: Part I. General considerations

Abstract The principle of a novel continuous titration technique with triangle-programmed reagent addition is described. The advantages of titration techniques, i.e. high precision, reliability, etc., are combined with the convenience and fast sample handling of mechanized analyzers of the flow-through type. The theoretical titration curves are discussed for detectors with logarithmic and linear signal conversion characteristics. The possibilities of different types of programmed reagent addition are summarized

A novel titration technique for the analysis of streamed samples—the triangle-programmed titration technique: Part II. Argentimetric titrations

Abstract An apparatus is described for carrying out triangle-programmed titrations with coulometric reagent generation. Different halides and pseudohalides can be determined by titration with silver(I). Both voltammetric and potentiometric detection systems are discussed, but emphasis is placed on potentiometric detection with ion-selective electrodes. The proposed technique can be used for accurate determinations of flowing samples of halides and pseudohalides at low concentrations. The simultaneous determination of two-component mixtures is discussed.

A novel titration technique for the analysis of streamed samples — the triangle-programmed titration technique : Part 3. Titrations with Electrically Generated Bromine

Abstract The triangle-programmed titration technique brings together the advantages of flow-through techniques and titration methods. Titrations with bromine prepared by current-programmed electrolysis are reported; suitable instrumentation is described for biamperometric end-point indication. The electrode processes and the effects of different parameters of the reagent addition program are discussed. The applicability of the method to organic and inorganic substances is described. The technique is applicable to flowing sample solutions of small volume, and the rate of analysis is similar to that achieved with other semi-automated analyzers.

THE VOLTAMMETRIC APPLICATION OF SILICONE RUBBER BASED GRAPHITE ELECTRODES WITH SPECIAL REGARD TO FLOWING SYSTEMS

The authors report on the silicone rubber based graphite electrode, a sensor applicable in the anodic polarization range. In addition to the voltammetric properties of the electrode, some applications are also presented in which the electrodes, incorporated in flow-through cells, were used for solving some practical problems.

A detailed study of sample injection into flowing streams with potentiometric detection

Abstract A new method developed by combining manual or coulometric injection into flowing streams and potentiometric detection is described. The potential-time curves obtained in a flow-through detector as a result of single injections are handled theoretically and examined practically. The effects of experimental parameters, concentrations and flow rates on the signal are discussed. A systematic survey of the potential use of the technique in analysis is given. Species can be determined easily either in the flowing stream or in the injected sample. Some applications in pharmaceutical and other types of analysis are listed, and the main advantages of the technique are summarized.

Application of silicone rubber-based graphite electrodes for continuous flow measurements: Part I. general relationships

Abstract The behaviour of the silicone rubber-based graphite electrode was studied. The relationship between the surface area of the electrode and the voltammetric current constant was established. The applicability of the silicone rubber-based graphite electrode in the continuous analysis of electrolyte flows was also investigated. At constant potential, the current exhibited a linear dependence on the concentration of the depolarizer and on the square root of the flow rate.

The flat surfaced membrane coated mercury electrode as analytical tool in the continuous voltammetric analysis

Abstract Specific analytical problems often arise which can be easily solved if a mercury electrode of constant surface area is used as voltammetric sensor. In this work a membrane covered mercury electrode was prepared and used in solving various analytical tasks. One of them was the determination of water hardness. A sample injection method was developed applying EDTA reagent and a flow-through analytical system. Two different voltammetric enzyme electrodes (measuring glucose and L-amino acid) were prepared by using the membrane covered mercury electrode as base sensor. The application of the enzyme electrode in flow-through circumstances was proved to be very advantageous in determining selectively L-DOPA in the presence of the D-form.

Determination of the prostaglandin F2α content of pharmaceutical preparations with triangle programmed bromimetric titration in flowing solutions

A survey of the different methods for prostaglandin analysis is given. The use of bromine as a reagent for the accurate determination of prostaglandin F2α is indicated from its chemical structure. Several reasons, however, hinder the use of classical bromimetry.In this paper the application of a new analytical method, the so-called triangle programmed titration technique, is described for prostaglandin analysis. This method permits the simple and effective use of bromine as a reagent by performing the titration in a continuous-flow system. The reagent is generated coulometrically during the titration.Methods are described for the determination of the prostaglandin F2α content of different pharmaceutical preparations.

Novel electroanalytical techniques for pollution analysis

ZusammenfassungZwei neue Methoden werden beschrieben. Die sog. Injektionstechnik wertet ein dynamisches Konzentrationssignal aus, das sich aus der Änderung in einem Durchflußkanal ergibt, wenn Probe oder Reagens in kleinen Volumina in einen konstant fließenden Flüssigstrom injiziert werden. Das zweite Verfahren, die programmierte coulometrische Titration, erlaubt die Anwendung der genaueren titrimetrischen Technik auf fließende Lösungen. Bei beiden Methoden werden potentiometrische und voltammetrische Detektoren verwendet. Mehrere Beispiele zeigen die vielfachen Vorteile dieser Verfahren bei der Anwendung auf die Analyse von Umweltmaterial.SummaryTwo new analytical techniques are described. The so-called injection technique operates on evaluating a dynamic concentration signal as a result of following the concentration change in a certain part of a flow-through channel after injecting a sample or reagent at a small volume into the current of an appropriate solution flowing at a constant rate.The second technique, the programmed coulometric titration technique, also uses the flow-through channel principle; that means this novel technique allows the more precise titrimetric way of analysis in flowing solutions. In the case of both techniques potentiometric and voltammetric detectors were involved. Several examples proved the multifold advantages of these techniques for environmental analysis.