A comparative study of Linear range, Sensitivity (S) and Limit of Detection (LOD) for two metal oxide nanocomposite enzyme based biosensors PANI/ZnO/Urease and PANI/MnO2/Urease for the detection of heavy metal ion Hg (ii) in water

Out of all the environmental issues, water pollution by heavy metal ion such as Mercury, Lead Arsenic, Cadmium, Chromium etc most important to be solved. Biosensors present an efficient alternative technique which can lead to the low cost heavy metal ion detector along with the features such as no need of special training for an operator, easily disposable, quick detection and less time consumption. In the present work, we have developed and compared two types of electrochemical amperometric biosensor by immobilizing Urease, to Stainless steel transducer. The stainless steel electrode was modified with PANI/ZnO and PANI/MnO2 nanocomposite by the method of electropolymerize-tion. Different parameter such as Linear Range, Sensitivity (S) and Limit Of Detection (LOD) were determined and compared. Finally the selectivity of the individual biosensor towards Hg (II) ions was studied by mixing another heavy metal ion Pb(II) in the same solution. It was observed that with increasing amount of Hg (II) ions the response current also increased linearly in the range from 2 mg/l to 7 mg/l. The detection limit was calculated to be 5.04 mg/l. The linear regression equation was I (mA) = y = 0.432[Urea Conc.] + 0.192 with correlation coefficient (R2) of 0.980. The obtained high sensitivity value 0. 432 mA/(mg/l) indicated that the proposed biosensors are excellent platform for sensitive detection of Hg (II).