Phenolic compounds modified electrodes

Detection of Caffeic Acid and Phenolic Compounds Using Electrodes Modified with Phthalocyanine Complexes of Non-transition Metals... 

Hydroxy derivatives or phenolics are frequent target for method development using carbon paste electrodes based either on direct oxidation of hydroxy group on an aromatic ring or on enzyme-based reactions with the final determination of the product of the enzymatic reaction involved. The reason lies both in their usual ease of oxidation and in their relatively frequent occurrence as hydroxy derivatives of aromatic hydrocarbons form the base of various biologically active organic compounds used as disinfectants, pharmaceuticals, herbicides, and pesticides. CPE and CPE modified with humic acids were used for the determination of pentachloro-phenol. With modified electrode lower determination limit was reached due to better accumulatiOTi of the analyte. Formation of a quinone-Uke compound during... 

Other materials were also employed to construct electrodes for amperometric detection. For instance, a boron-doped diamond (BOD) electrode was used for amperometric detection of nitroaromatic explosives, organophosphate nerve agents, and phenols. The BOD electrode offers enhanced sensitivity, lower noise, negligible adsorption of organic compounds, and low sensitivity to oxygen [760], In addition, a copper particle-modified carbon composite electrode was used for amperometric detection of glucose in a PDMS chip [761]. 

Voltammetric sensors based on chemically modified electrodes (conducting polymers, phthalocyanine complexes) with improved cross-selectivity were developed for the discrimination of bitter solutions [50], The performance and capability were tested by using model solutions of bitterness such as magnesium chloride, quinine, and four phenolic compounds responsible for bitterness in olive oils. The sensors gave electrochemical responses when exposed to the solutions. A multichannel taste sensor was constructed using the sensors with the best stabilities and cross-selectivities and PCA of the signals allowed distinct discrimination of the solutions. 

Litescu, SC, Cioffi, N, Sabbatini L, Radu G.L. (2002), Study of Phenol-Like Compounds Antioxidative Behavior on Low- Density Lipoprotein Gold Modified Electrode, Electroamlysis, 14(12), 858-865, ISSN 1041L0397... 

Figure 1. Reaction scheme of enzyme-modified electrodes for the determination of phenolic compounds. CDH is cellobiose dehydrogenase and GDH is PQQ-dependent glucose dehydrogenase. Ph, Ph and Q are the phenolic molecule, its phenoxy radical, and its quinone, respectively.

Haghighi, B., A. Rahmati-Panah, S. Shleev, and L. Gorton, 2007. Carbon ceramic electrodes modified with laccase from Trametes hirsuta Fabrication, characterization and their use for phenolic compounds. Electroanalysis 19 907-17. 

Haghighi, B., L. Gorton, T. Ruzgas, and L. J. Jonsson. 2003. Characterization of graphite electrodes modified with laccase from Trametes versicolor and their use for bio-electrochemical monitoring of phenolic compounds in flow injection analysis. Anal. Chim. Acta 487 3-14. 

Francisco MSP, Cardoso WS, Kubota LT, GusUkem Y (2007) Electrocatalytic oxidation of phenolic compounds using an electrode modified with Ni(II) porphyrin adsorbed on Si02/ Nb205-phosphate synthesized by the sol-gel method. J Electroanal Chem 602 29-36... 

The work reported the applicability of a voltammetric BioET to the monitoring of different phenolic pollutants present in wastewaters. Voltammetric responses obtained from an array of bulk-modified (bio)sensors, containing enzymes such as tyrosinase and laccase, were combined with chemometric tools such as ANNs for building the quantitative prediction model. The four voltammetric electrodes prepared consisted in one blank electrode plus three (bio)composite electrodes modified with tyrosinase, tyrosinase-i-laccase and Cu nanoparticles. This choice was intended as to maximize the response of the (bio)sensor array towards phenolic compounds. That is, on one side, tyrosinase and laccase were chosen as they are extensively used for the development of amperometric biosensors aimed to the detection of phenolic compounds on the other side, copper nanoparticles were also considered due to the well-known catalytic properties of nanoparticles and the importance of copper in the two enzymes used. To fully exploit all the information... 

Determination of Phenolic Compounds IN Wines with Tyrosinase Modified Electrodes... 

In this paper we describe the use of several clays (sepiohte, bentonite and hectorite) as modifiers of carbon paste electrodes in the determination of the following organic compounds fiunitrazepam, nitrobenzene, aniline, phenol, linuron, dinocap and endosulfan. 

In one of the first works using electrodes modified with metallo-N4 complexes for the detection of organic compounds, Mafatle et al. [44] used GC electrodes modified with unsubstituted metallophthalocyanines MPc (GC/MPc), where M = Co, Mn, Fe, Ni, Zn, and also with unmetalated H2PC, as electrosensors for cresols, chlorophenols and phenols. The adsorbed MPc films were prepared by the drop-diy method. Using cyclic voltammetry at 0.1 V s in 0.05 M H2SO4, the GC/CoPc electrode showed higher oxidation currents and less fouling than the unmodified GC electrodes. If CoTSPc was added to the aqueous solution, the activity of bare GC electrodes also increased. 

Four-element arrays, with each element consisting of three Pt electrodes (one modified 30 pm x 30 pm square working, one counter and one Pt pseudoreference), have been fabricated on glass substrates for the detection of the anabolic steroid albuterol, which is a doping concern in athletics and has been used as a food supplement for farm animals [88]. The arrays are based on working electrode modification with a molecularly imprinted polymer that is selective for albuterol over clenbuterol and terbutaline, two closely related compounds. The arrays are reusable (at least 20 times) and linear responses, as differential pulse voltammetric peak currents, for the oxidation of phenolic hydroxyl groups at about +0.45 V, occur over the 1-50 pM concentration range of albuterol. The molecularly imprinted polymer electrode films allow discrimination over similarly functionalized interferants. 

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