Titania sol-gel-derived tyrosinase-based amperometric biosensor for determination of phenolic compounds in water samples. Examination of interference effects

For detection of phenolic compounds in environmental water samples we propose an amperometric biosensor based on tyrosinase immobilized in titania sol gel. The analytical characteristics toward catechol, p-cresol, phenol, p-chlorophenol, and p-methylcatechol were determined. The linear range for catechol determination was 2.2 x 10(-7) - 1.3 x 10(-5) mol L-1 with a limit of detection of 9 x 10(-8) mol L-1 and sensitivity 2.0 x 10(3) mA mol(-1) L. The influence of sample matrix components on the electrode response was studied according to Plackett-Burman experimental design. The potential interferents Mg2+, Ca2+, HCO3-, SO42- , and Cl-, which are usually encountered in waters, were taken into account in the examination. Cu2+ was also taken into account, because CuSO4 is sometimes added to a water sample, as a preservative, before determination of phenolic compounds. It was found that among the ions tested only Mg2+ and Ca2+ did not directly affect the electrode response. The developed biosensor was used for determination of catechol in spring and surface water samples using the standard addition method.