Impedimetric method

Nielsen, P.V. 1991. Preservative and temperature effects on growth of the three varieties of the heat-resistant mold Neosartorya fischeri, as measured by an impedimetric method. J. Food Sci. 56, 1735-1740. 

Three broad classifications of electrochemical methods are used in this chapter. Po-tentiometric methods include zero-current potentiometry and methods in which current of controlled magnitude is apphed to the working electrode, such as in potentiometric stripping analysis (PSA). Amperometric methods consider all techniques in which current is measured these include constant-potential amper-ometry and amperometric measurements made in response to a variety of applied potential waveforms in voltammetric methods. Impedimetric methods comprise a final classification in these methods, faradaic currents are generally absent, and impedance, conductance, or capacitance is the measured property. 

Impedimetric measurements are based on the nonfaradaic response observed between two electrodes immersed in a sample solution when a high frequency (1 to 300 kHz) alternating potential is applied. The amplitude of the applied waveform is small, and this, combined with the high frequency relative to other electrochemical methods, effectively prevents faradaic reactions from occurring to any significant extent. In contrast to potentiometric and amperometric methods, impedimetric methods are not analyte-selective instead, bulk properties of the solution and the electrode-solution interfaces are monitored. 

Tran HV, Reisberg S, Piro B, Nguyen TD, Pham MC (2013) Label-liee electrochemical immunoaffinity sensor based on impedimetric method for pesticide detection. Electroanalysis 25 664-670... 

Polypyrrole has the potential to provide an effective method for reagentless transduction by immobilization of the ssDNA probe within the polymer matrix. Significant differences in the impedance profile of ssDNA and dsDNA have been demonstrated [59]. The differences in the impedance profile are purportedly based on intercalation differences of the polymer with ssDNA compared to dsDNA. The exact mechanism for impedimetric change resulting from conducting polymer films has not been identified, although it is likely linked, much like the impedimetric response of pure DNA, to the change in ion density that accompanies the double strand compared to the... 

An alternative competitive impedimetric assay for analyzing neomycin B was demonstrated (de-los-Santos et al., 2007) (Figure 3.10A). A gold electrode was modified with neomycin B, and the respective RNA aptamer was linked to the surface. The resulting neomycin B-aptamer complex introduced an electron-transfer barrier to the solution-solubilized redox label FeCCN) , and this resulted in high interfacial electron-transfer resistance. In the presence of neomycin B, partial displacement of the aptamer occurred, and this resulted in a decrease in the interfacial electron-transfer resistance. Since the extent of the aptamer displacement was controlled by the concentration of neomycin B, the quantitative analysis of the substrate was achieved (Figure 3.10B). The method was applied successfully to analyze neomycin B in milk. 

Table 16.2 Comparison of the working temperature (T), electrical response, sensing material and method employed in different works related to impedimetric CO2 gas sensors...

P. Van Gerwen, K. Baert, and R. Rossau. Impedimetric detection system and method of production thereof. US Patent 6440662, assigned to Innogenetics N. V. (Ghent, BE), August 27,2002. 

The same group discussed recently described impedimetric detection methods for double-tagged DNA from PCR amplification of Salmonella spp. [77]. One of these methods involved amplification of the impedimetric signal by using a monoclonal IgGlkappa anti-... 

Biospecificity is the property of the biorecognition membrane of the biotransducer that is conferred by the purposeful use of a bioactive receptor. There exists a wide range of possible approaches to the conferment of biospecificity to impedimetric array biosensors. These methods vary somewhat depending upon the bioactive receptor to be immobilized (molecule, subcellular fragment, cell, or tissue). However, these methods have one... 

Electrochemistry works using the principles of oxidation-reduction reactions which generate electric currents or, more simply, the conversion of chemical information into an electrical signal. Electrochemical cells or sensors usually contain a working electrode, to which a potential is applied, and a reference electrode. The oxidation-reduction reaction that ensues is then recorded as an electric current which is a measurement of the analyte from the reaction. Electrochemical methods can be further subdivided into amperometric (measures current), potentiometric (measures potential), conductometric (measures the conductive properties of the medium), impedimetric (measures resistance and reactance) or field effect (measures current through charge accumulation at a gate electrode). ... 

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