The impedance‐titrator : A novel setup to perform automated pH‐dependent electrochemical experiments

Fenster, Christian; Rohwerder, Michael; Hassel, Achim Walter

doi:10.1002/maco.200905384

Cited by 7 publications

(5 citation statements)

References 11 publications

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“…In principle, it is also conceivable to prepare protein samples manually in buffers at different pH values, but in practice, such an endeavor would be characterized by low pH resolution. Previously, Fenster et al developed an impedance titrator, in which the pH of a solution is automatically adjusted to a certain alkaline pH value or scanned through the alkaline pH range in a stepwise manner with a step width of pH 0.25 during electrochemical experiments . Likewise, pH controllers have also been developed for industrial and hydroponic cultivation to maintain a specific pH of water in large reservoirs.…”

Section: Resultsmentioning

confidence: 99%

“…Previously, Fenster et al developed an impedance titrator, in which the pH of a solution is automatically adjusted to a certain alkaline pH value or scanned through the alkaline pH range in a stepwise manner with a step width of pH 0.25 during electrochemical experiments. 52 Likewise, pH controllers have also been developed for industrial 53 and hydroponic cultivation 54 to maintain a specific pH of water in large reservoirs. The protein experiments on milliliter volume samples (1.5−5 mL) we intended to perform in our laboratory require an automatic microtitration system that can essentially cover both acidic and alkaline pH ranges.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

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Scanning pH-metry for Observing Reversibility in Protein Folding

et al. 2022

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One of the main factors affecting protein structure in solution is pH. Traditionally, to study pH-dependent conformational changes in proteins, the concentration of the H+ ions is adjusted manually, complicating real-time analyses, hampering dynamic pH regulation, and consequently leading to a limited number of tested pH levels. Here, we present a programmable device, a scanning pH-meter, that can automatically generate different types of pH ramps and waveforms in a solution. A feedback loop algorithm calculates the required flow rates of the acid/base titrants, allowing one, for example, to generate periodic pH sine waveforms to study the reversibility of protein folding by fluorescence spectroscopy. Interestingly, for some proteins, the fluorescence intensity profiles recorded in such a periodically oscillating pH environment display hysteretic behavior indicating an asymmetry in the sequence of the protein unfolding/refolding events, which can most likely be attributed to their distinct kinetics. Another useful application of the scanning pH-meter concerns coupling it with an electrospray ionization mass spectrometer to observe pH-induced structural changes in proteins as revealed by their varying charge-state distributions. We anticipate a broad range of applications of the scanning pH-meter developed here, including protein folding studies, determination of the optimum pH for achieving maximum fluorescence intensity, and characterization of fluorescent dyes and other synthetic materials.

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Section: Resultsmentioning

confidence: 99%

Section: ■ Results and Discussionmentioning

confidence: 99%

Scanning pH-metry for Observing Reversibility in Protein Folding

et al. 2022

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“…Accurate descriptions of the setup are given elsewhere . A typical three electrode configuration was used for performing electrochemical measurements.…”

Section: Methodsmentioning

confidence: 99%

Film dissolution kinetics of aluminium at precisely adjusted pH‐values

Walkner

Hafner

Hassel

2016

Physica Status Solidi (a)

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This work focuses on the corrosion of aluminium in alkaline solution particularly at pH 11.0. The pH value plays a key role in corrosion processes. In a certain pH range, either the metal dissolves or protective films may be formed. For performing electrochemical measurements at a precisely adjusted pH value a setup, the so called 'impedance titrator' is used, that allows adjusting and controlling of pH value very precisely, while characterising the film properties. Electrochemical impedance spectroscopy is performed to investigate the formation of corrosion products. By keeping the pH at a constant value and simultaneously offering the system a constant hydroxide concentration, film formation takes place under defined conditions and a full kinetic characterisation becomes possible. This special system is required as the behaviour of aluminium in alkaline solution is quite complex and a various number of competing reactions like oxide film formation and dissolution occur.

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“…In a certain pH ‐range, either the metal dissolves or protective films may be formed. In other words, some metals dissolve easily under alkaline conditions, while some metals are susceptible to acidic dissolution or even doing both, thus being amphoteric. The situation becomes more complicated during the anodizing of alloys having constituents with different electrochemical susceptibility to dissolve in a particular electrolyte .…”

Section: Introductionmentioning

confidence: 99%

A Thermodynamic Approach for Selection of Anodizing Electrolytes in Aluminium‐Holmium System

Shahzad

Mardare

et al. 2020

ChemElectroChem

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In this paper, an approach is described for the electrolyte selection to grow optimally anodic films on thermally co‐evaporated aluminium and holmium combinatorial alloys. This method based on thermodynamic and electrochemical principles proves that electrolyte selection for anodizing of alloys having different microstructures and electrochemical behaviour of individual constituents can be decided by superimposing potential‐pH diagrams of individual constituents of the alloy. For the application of this approach, the most widely investigated valve metal, aluminium, and a non‐valve metal rare earth, holmium, have been chosen as a model case. Based on self‐constructed Eh‐pH diagrams and solubility data, suitable electrolytes and pH range leading to the formation of barrier‐type anodic films on aluminium and holmium as well as on their alloys are proposed.

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The impedance‐titrator : A novel setup to perform automated pH‐dependent electrochemical experiments

Cited by 7 publications

References 11 publications

Scanning pH-metry for Observing Reversibility in Protein Folding

Scanning pH-metry for Observing Reversibility in Protein Folding

Film dissolution kinetics of aluminium at precisely adjusted pH‐values

A Thermodynamic Approach for Selection of Anodizing Electrolytes in Aluminium‐Holmium System

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