Phenol-specific immunoassay

Phenol-specific immunoassay has also been used as a detection system in liquid chromatographic separation system [111]. The connection between HPLC and immunoassay detection was regarded by the authors to be more labor demanding than conventional HPLC-UV, but the payoff in selectivity and sensitivity is claimed to be immense. 

Possible obstacles to using immunoassays are created by environmental factors, such as pH, temperature, or other food product ingredients, e.g., endogenous enzymes whose specificity is similar to the specificity of the enzyme present in the conjugate, colorings present in a given samples can interfere with the color obtained from the enzyme-substrate reaction, phenolic compounds which can adsorb proteins. 

Lacc has a broad substrate specificity, it oxidizes a variety of diphenols. Inorganic and organic redox dyes, amino substituted phenols and catecholamines (12). On the other hand GDH accepts a number of redox mediators for glucose oxidation. Therefore, any substrate of Lacc, which oxidized form Is accepted by GDH can be determined by the Lacc-GDH electrode. Consequently, the sensor response is not selective for a certain substrate. However, this is not a problem for the cases described below, when only one of the substrates is present (immunoassays) or a mixture with unchanging ratio of catecholamines (norepinephrine and epinephrine) secretion is analyzed. The dependence of electrode response on the concentration of 8 different substrates is presented In Fig. 3. The optimal substrate is PAP, followed by epinephrine, ferroceneacetic acid, ferrocenecarboxylic acid, L-DOPA, arterenol, 1,1-ferrocendicarboxylic acid, and norepinephrine. It should be noted that for ascorbic acid no amplification was observed. 

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