Electropolymerization potentiometric

Other usefiil gas sensors include the potentiometric ammonia (64) or hydrogen cyanide probes (65), and amperometric carbon monoxide (66) and nitrogen dioxide (67) devices. The hydrogen cyanide probe is an example of a modem device that relies on changes in the conductivity of electropolymerized film (polyanihne) in the presence of a given gas. 

A nitrate-selective potentiometric MIP chemosensor has been devised [197, 198]. For preparation of this chemosensor, a polypyrrole film was deposited by pyrrole electropolymerization on a glassy carbon electrode (GCE) in aqueous solution of the nitrate template. Potentiostatic conditions of electropolymerization used were optimized for enhanced affinity of the resulting MIP film towards this template. In effect, selectivity of the chemosensor towards nitrate was much higher than that to the interfering perchlorate ( o3 cio4 = 5.7 x 10-2) or iodide ( N03, r = x 10 2) anion. Moreover, with the use of this MIP chemosensor the selectivity of the nitrate detection has been improved, as compared to those of commercial ISEs, by four orders of magnitude at the linear concentration range of 50 pM to 0.5 M and LOD for nitrate of (20 10) pM [197]. 

The potentiometric sensing of urea was also demonstrated by entrapping the enzyme urease within a polypyrrole membrane electrosynthesized on a platinum electrode [75]. The bioactive sensing membrane was synthesized by potentiostatic electropolymerization of pyrrole monomer in a solution containing the urease enzyme and a nucleophilic electrolyte such as NaOH, NaCOs, or NaHCOs. This biosensor exhibited a good Nemstian response to urea, with a slope of 31.8 mV/decade over an mea concentration range of 1.0x10 mo]/dm -0.3 mol/dm. ... 

Komaba, S., M. Seyama, T. Momma, and T. Osaka. 1996. Potentiometric biosensor for urea based on electropolymerized electroinactive polypyrrole. Electrochim Acta 42 (3) 383. 

Blair, T.L., J.R. Allen, S. Daunert, and L.G. Bachas (1993). Potentiometric and fiber optic sensors for pH based on an electropolymerized cobalt porphyrin. Anal. Chenu 65,2155-2158. 

But the most smdied electropolymerizable porphyrins are the tetra-amino-and tetrahydroxyphenyl-substituted ones. Indeed, both of them were developed to elaborate electrodes having potentiometric responses to several kinds of anions, such as iodide for example . Co(II) tetrakis(p-hydroxyphenyl)porphyrin 53-based films were used for the elaboration of potentiometric and fibre optic pH sensors with minimal interferences from anions. Zn(II)-53-based films were also used and characterized for kinetics studies of hydrogen evolution at their surface . Zn(II)-53 as well as Pd(II)-53 and free base tetra(4-methyl pyridinium) porphyrin (H2-54) were electropolymerized on indium tin oxide substrates, leading thus to starting materials for the making of donor/acceptor... 

Bruti, E.M., M. Giannetto, G. Mori, and R. Seeber (1999). Electropolymerization of tetrakis(o-aminophenyl)porphyrin and relevant transition metal complexes from aqueous solution. The resulting modified electrodes as potentiometric sensors. Electroanalysis 11(8), 565-572. 

To prepare polymer film electrodes there are different techniques like dip coating, spin coating, electropolymerization from monomers, and molecularly imprinted polymers (MIPs) developed very recently. They are often used for both potentiometric and amperometric ion sensors. Some feature of different types of ion sensors based on polymer CMEs are shown in Table 1. Conducting polymer-based CMEs... 

Functionalizations of metal/metal oxide or carbon nanotechnology with polymers are reported in potentiometric pH designs. Li et al. [31] demonstrated a simple fabricated polybisphenol A (PBPA), electropolymerized on indium thin oxide (ITO) for pH sensing. The PBPA/ITO exhibits a sensitivity of 58.6 1.4 mV/pH, near theoretical value, and can be stored for up to 12 days. Possible interferents such as Na", K", Cl, and S04 show no significant response. Jang and coworkers developed self-assembly nanobead polystyrene, deposited on Au/Bi in lab chip sensor. As shown in Fig. 7, the microfluid chip has two ion-selective membranes to H and NO3 species. 

A five-electrode system was used with an SBDP with a gold electrode to measure potentiometric response correlated to local pH change through a porous membrane. The same SBDP fabrication method reported for redox probe diffusion was used, but electropolymerization of aniline to polyaniline (PANi) film on the Au portion of the probe enabled pH measurement. A porous polyimide membrane was mounted in... 

Alvarez-Romero, G. A., S. M. Lozada-Ascencio, J. A. Rodriguez-Avila, C. A. Galan-Vidal, and M. E. Paez-Hernandez. 2010. Potentiometric quantification of saccharin by a selective membrane formed by pyrrole electropolymerization. Food Chem. 

Figure 3. Potentiometric pH response of a bare glassy-carbon electrode (A), and electrodes based on electropolymerized [Co(p-OH)TPP] (O) and electropolymerized phenol ( ). (Reproduce with pennissionfroin ref. 40. Copyright 1993 American Chemical Society.)...

More recently, a new, simple, sensitive, low cost, and rapid potentiometric method for direct determination of ultra-trace amounts of SDS with a new DS selective electrode was reported. The electrode was prepared by electropolymerization of aniline on the surface of a Pt electrode in acidified solutions containing DS ions. The sensor showed a Nemstian behavior response of... 

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