Sensors for Phenols and Amines

Phenols are important intermediates of coal processing their concentration in wastewater is relevant for pollution control. Furthermore, various drugs such as adrenaline and noradrenaline belong to this class of substances. 

For the determination of phenols and amines enzymes with low selectivity, e.g. laccase, horseradish peroxidase, tyrosinase, and polyphenol oxidase, as well as specific enzymes, e.g. phenol hydroxylase and catechol-1,2-oxygenase, can be used in biosensors. 

A laccase electrode for the determination of the lignin content of wood has been described by Malovik et al. (1983). The samples were extracted with organic solvent and the extracts directly injected into the measuring cell. 

Laccase also catalyzes the 02-dependent oxidation of ascorbic acid, ferrocyanide, iodide, and uric acid. These reactions have been utilized to eliminate electrochemical interferences in amperometric hydrogen peroxide detection at membrane-covered enzyme electrodes (Wollen-berger et al., 1986). The capacity of the laccase membrane to oxidize ferrocyanide has been characterized by anodic oxidation of ferrocyanide at +0.4 V (Fig. 62). When a fresh enzyme membrane is used, a current signal appears only at substrate concentrations above 5 mmolA the current increases linearly with increasing concentration. This threshold concentration decreases with increasing membrane age until the remaining enzyme activity is too low for complete substrate oxidation. 

The flavoprotein phenol-2-hydroxylase (EC 1.14.13.7) and the o-phenol-splitting catechol-1,2-oxygenase (EC 1.13.1.1) are prepared from 

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