III International Conference

PP-III-4THE PREPARATION AND TESTING OF A MODIFIED POLYANILINE BASEDELECTRODE AS A SENSOR FOR THE DETERMINATION OF ANTIOXIDANTCONTENTEfimov O.N., Abalyaeva V.V.Institute of Problems of Chemical Physics, RAS, Chernogolovka, Moscow region, RussiaE-mail: efimov@icp.ac.ruOver the past years special attention in medicine is given to free radicals formed as aresult of vital activity of living organisms. The best protectors from the destroying effect offree radicals are antioxidants, a large family of biologically active compounds widely spreadin nature. According to the standpoint of physicians, high everyday level of consumption ofantioxidants provides the maintainance of a desired antioxidation status of organisms.There are analytical methods to determine antioxidation activity of food 1 , most of themare suitable for laboratory expereiments but can hardy be used for the analysis in foodproduction and in proximate analysis.Thus, it seems reasonable to develop easy operating analytical devices, namely,electrochemical sensors comprising a chemically modified electrode (CME) as the mainsesitive unit. The operating principle of such CME is based on the reaction of a catalyticallyactive mediator (oxidant), which is invloved in the electrode coating, with an antioxidant(reductant) at the CME/electolyte interface followed by the regeneration of an oxidized formof a radical as a result of electron transfer to an electrode in the polymer bulk. The insertion ofa modifier (catalyst) into a modified electrode allows one to enhance electrode sensitivity andprovides a linear dependency of current on concentration in the tested antioxidant solutions.An organic mediator, 2,2 / -azino-bis(3-ethylbenzthiasoline-6-sulfonic acid (ABTS), and aninorganic mediator, hexachloroirideate anion (IrCI 2- 6 ), were tested as mediators. Trolox,ascrbic, uric and gallic acids were used as model antioxidants. Conventional electrodematerial is Pt, which essentially enhances the cost of a resulting product. We developed ageneral approach, which consists in using metal complex catalysts 2 to prepare high qualitypolyaniline (PAn) coatings on various supports coated even by an oxide film that allows Pt tobe replaced with more available and cheaper ecologically clean (pure) materials.This work reports on the preparation and investigation of CME based on PAn, and ABTS2-or IrCI 6 mediators inserted into a polymer matrix. The PAn coatings were prepared onglassy carbon, tantalum and titanium electrodes using electrosynthesis. The mediator was476