Application Finder

In the application note AN-EIS-004 on equivalent circuit models, an overview of the different circuit elements that are used to build an equivalent circuit model was given. After identifying a suitable model for the system under investigation, the next step in the data analysis is estimation of the model parameters. This is done by the non-linear regression of the model to the data. Most impedance systems come with a data-fitting program. In this application note, the way NOVA is uses to fit the data is shown.

In this application note, the advantage of recording the raw time domain data for each individual frequency during an electrochemical impedance measurement is described.

Electrochemical impedance spectroscopy (EIS) is a powerful technique which provides information about the processes occurring at the electrode-electrolyte interface. The data collected with EIS are modeled with a suitable electrical equivalent circuit. The fitting procedure will change the values of the parameters until the mathematical function matches the experimental data within a certain margin of error. In this Application Note, some suggestions are given in order to get acceptable initial parameters and to perform an accurate fitting.

This Application Note presents the Mott-Schottky measurement, an extension of electrochemical impedance spectroscopy (EIS), on a popular semiconducting material.

A fuel cell is an electrochemical energy conversion device that produces electricity and heat by electrochemically combining a fuel (typically hydrogen) and an oxidant (typically oxygen). The higher efficiency also results in much lower carbon dioxide emissions and negligible amounts of SOx and NOx (when reformed fuel is used) compared with fossil fuel-based technologies for the same power output.

To overcome the various technical problems, many different fuel cell types have been developed. In this Application Note, proton exchange membrane, direct methanol and solid oxide fuel cells are discussed in more detail.

In this Application Note the use of Electrochemical Impedance Spectroscopy (EIS) for the characterisation of PEM fuel will be demonstrated. It will be shown that EIS is a powerful diagnostic tool for the determination of the following factors that can influence the performance of a PEM fuel cell.

In this application note, a combination of PGSTAT and electronic load is use to perform electrochemical impedance spectroscopy in a fuel cell operating at high currents.

The use of impedance measurements on fuel cells under load makes it possible to study the influence of the different fuel cell elements on the behavior and (if detectable) on the ageing of the fuel cell. To perform high current density measurements, the Autolab systems can be connected to a third party electronic load. This extends the measurable range of the instrument by several current decades.

The operational behavior of a fuel cell stack is usually evaluated by determining the polarization and power density curves of the cell. These curves provide a quick characterization of the stack performance and an assessment of its optimal operating conditions (temperature, humidity, electrocatalyst, ion-exchange membrane).

In recent years, field-effect transistors (FETs) have become more commonly used as a sensing platform for a multitude of electrochemical and biological applications. These devices are promising bioelectronic transducers that allow both low-potential operation and stable potentiometric measurements. FETs are now seen as an attractive alternative to using conventional electrochemical detection systems in the scientific community. This Application Note gives in-depth guidance about how to operate Metrohm DropSens bipotentiostat devices for the characterization of FETs and their use as transducers. A single μStat-i 400 device, a small and portable bipotentiostat and galvanostat, is used to demonstrate the experiments.

In this Application Note, the Metrohm DropSens SPELEC instrument is used with the FLUORESCENCE KIT for time-resolved monitoring of electrochemical reactions in a semi-infinite diffusion regime by performing fluorescence spectroelectrochemistry of the [Ru(bpy)3]2+/3+ redox couple.

Alamar Blue is monitored with fluorescence spectroelectrochemistry during its irreversible reduction to resorufin and further reversible reduction to dihydroresorufin.

Determination of Total Acid Number (TAN) values in mineral oils and similar fluids.

Determination of the sulfate content of wet process phosphoric acid.

This Application Note explains how fluoride determination in acid etching baths can be performed with thermometric titration.

Determination of cuprous ions in the presence of ferrous ions in electrochemical copper leaching solutions.

Determination of a nonionic surfactant of the alkyl propylene oxide derivative type in commercial mixtures containing anionic surfactants.

Standardisation of sodium tetraphenylborate (NaTPB) solution for the determination of potassium and for nonionicsurfactants.

Determination of soluble orthophosphate ions, for example soluble phosphate in fertilizers such as DAP.

Determination of the sulfate content of brines.

Thermometric titration quickly and accurately assesses the total solids content of fluids employed in drilling oil and gas wells within minutes.

Thermometric titration is presented as a simple, fast, and reliable method to determine calcium content in various drilling fluids.

Determination of ferrous ions in heat exchanger and vessel acid wash solutions, for measuring the effectiveness of acid inhibitors used in the solutions. Depending on the condition of the sample, the lower practical limit for the determination will vary from approximately 20-100mg/Kg Fe2+. Samples with high silicic acid contents require relatively large amounts of dilution water to render them mobile, and this limits the aliquot size and hence the amount of Fe2+ which can be analyzed.

Determination of water in moist particulate solids such as cobalt oxyhydroxide.

Determination of free acid in solutions containing metal ions, particularly Fe(III).

Determination of acetic anhydride in the presence of acetic acid in acylation mixtures.

Determination of mixtures of phosphoric, nitric, and acetic acids used in etching aluminum in the manufacture of semiconductor devices.

Determination of bromide and chloride in photographic developer solutions.

Determination of chloride in oil well drilling fluids.

Determination of chlorine in household bleaches.

Determination of chromium in leather waste solutions in the range between 1000 and 30,000 ppm.

Determination of free acid in copper refining solutions.

Determination of moisture in lubricating oils with TEOF (triethyl orthoformate).

Determination of nickel in the absence of cobalt and other interferences.

Determination of tar acids in coal tar products. This procedure may also be applied to the determination of a range of weakly acidic organic compounds such as carboxylic acids, hydroxy acids, phenols, phenolic acids, keto-enols, imides, and aromatic nitro compounds.11 Vaughan, G. A. Thermometric and Enthalpimetric Titrimetry. Van Nostrand Reinhold Co. Ltd (1973)

Determination of water in automotive lubricating oils.

This Application Note describes a method for the determination of causticizer, carbonate and aluminum oxide in used Bayer process liquors. The method is based on processes that were developed by Watts-Utley and VanDalen-Ward.

Determination of total basicity of extractable organic compounds of acidic character in Bayer process refinery liquors.

Standardization of 0.1 mol/L in propan-2-ol for use in applications for the determination of weakly acidic species in non-aqueous media.

Determination of chlorite by direct thermometric titration with standard sodium thiosulfate solution. The procedurewas applied originally to the determination of chlorite in hide treatment solutions.

Determination of low levels of sulfate (to approximately 20mg/L SO42-) by thermometric titration.

Standardization of 0.1 mol/L ammonium ferrous sulfate solution for use in thermometric titration of Cr(VI) solutions.

Determination of low levels of chloride (to approximately 5 mg/L Cl-) by thermometric titration.

Determination of calcium and magnesium in process solutions.

Phosphorus is a primary macronutrient for plants and is a constituent of DNA and adenosine triphosphate (ATP), which is involved in many biological processes requiring energy. In fertilizers, phosphorus is present in the form of phosphate, as the most accessible form of phosphorus for plants is dihydrogen phosphate. Knowledge of the phosphorus content helps to select the right fertilizer for the plants.Traditionally, phosphate is determined gravimetrically (a time consuming procedure) or spectrophotometrically (expensive instrumentation). In this Application Note, an alternative method is presented, where phosphate is determined by a precipitation titration with magnesium. Various solid and liquid NPK fertilizers with phosphorus contents between 6.5 and 17% were analyzed. The analysis by thermometric titration requires no sample preparation in case of liquid NPK fertilizers and only minimal sample preparation in case of solid NPK fertilizers. One determination takes about 5 minutes.

Determination of free fatty acids (FFA) in oils.

Determination of phosphate content in an acid etching bath.

Determination of sulfate and total acids in a nitrating mixture.

Determination of sodium lauryl ether sulfate surfactants.