[An enzyme sensor for phenolic compounds analysis]

Phenolic analysis was established on the immobilized horseradish peroxidase (HRP) catalyzed oxidation reaction. It subsequently catalyzed oxidative coupling of phenol with 4-aminophenazone using aqueous hydrogen peroxide to form intensely colored products for spectrophotometric analysis. HRPs were trapped in sol-gel matrix in a mild procedure. The immobilized HRPs maintain almost identical enzymatic activity as those in solution. BET analysis indicates that the silica itself is a porous structure with the average pore diameter of 2.95 nm. It permits small size molecules i. e. hydrogen peroxide, phenol and 4-aminophenazone to diffuse into the matrix while large molecules like enzyme (HRP) remain in the pores. It thus allows a biocatalysis to occur and makes the most out of the enzymes encapsulated in the silica matrix to stand against leakage so that the immobilized horseradish peroxidase could be recycled. The method can be employed for 2-chlorophenol, 3-chlorophenol or 2,4-dichlorophenol analysis as well. The feasibility of recycle on immobilized enzyme is evaluated. Although enzymatic activities are obviously decreased after repeated utilization of 9 times, the method definitely offers a potential spectrophotometric biosensor for phenolic compounds analysis.