Sensitive and Selective Detection of Mercury Ions by Potentiometric Biosensor Based on Urease Immobilized in Chitosan-Poly(Vinyl Alcohol) Hydrogel Film

In this paper, a potentiometric biosensor was fabricated by immobilizing urease into chitosan- poly(vinyl alcohol) hydrogel film at the surface of a pH electrode. Based on the inhibition effect of Hg 2+ to the activity of immobilized urease, the proposed biosensor was used for detection of Hg 2+ . The results showed that the inhibition rate exhibited a good linear relationship with the logarithm of Hg 2+ concentration in the range from 0.002 μM to 2μM. Defined as 10% inhibition rate, the detection limit was found to be 0.001 μM. The concentration for 50% inhibition rate was calculated to be 0.03μM. Furthermore, the proposed biosensor exhibited excellent selectivity to Hg 2+ . Other heavy metal ions, such as Ag + , Cu 2+ , Pb 2+ , Cd 2+ have littler influence on Hg 2+ determination. The biosensor was successfully applied for determination of Hg 2+ in industrial wastewater samples. The results obtained by the biosensor were consistent with those measured by inductively coupled plasma mass spectrometry (ICP-MS) method.