Procedure 20 Determination of methyl mercury in fish tissue using electrochemical glucose oxidase biosensors based on invertase inhibition
This chapter discusses the effect of the inhibitor in the presence and in the absence of the matrix. For the very low concentration of methyl mercury very low concentration of the enzyme invertase has been used (0.05 μg/mL) because at this concentration the enzyme is more sensitive toward methyl mercury using the biphasic system. The principle of combination of electrochemical glucose oxidase biosensor with the clean-up method for direct extraction and determination of methyl mercury has been successfully demonstrated. The extraction of methyl mercury from the organic solvent has been based on invertase enzyme inhibition. The combination of very low concentration of invertase enzyme and 10 min of incubation time allows the detection of methyl mercury at 5 ppb level. The method permits the detection of this inhibitor below the legal limit given by the European Union with good recoveries when fish samples have been measured. The chapter demonstrates a simple and rapid screening method for determination of methyl mercury in organic solvent using invertase inhibition. The method is free from interferences using the solvent extraction combined with the invertase enzyme.