Development of Amperometric Enzyme Biosensor for Determination of Heavy Metal Ions in aqueous samples

¹Maitera O.N, ²Buba M, and ³I.I Nkafamiya

^1&3Department of chemistry, Modibbo Adama University, Yola Adamawa State Nigeria

²Department of Science Laboratory Technology, Federal Polytechnic, Mubi Adamawa State

Corresponding author :- bubanenne58@gmail.com

ABSTRACT

An amperometric urease inhibition-based biosensor was developed to detect Pb²⁺ and Cr³⁺ ions in water matrix. The modified GCE/ZnO/urease electrode was developed by immobilizing ZnO nanoparticles and urease using gelatin and glutaraldehyde as crosslinking agent. With urea as a substrate, ZnO catalytic activity was examined through cyclic voltammetry. Working conditions of the biosensing system were optimized in terms of current generated in the presence of substrate (urea) as a function of different variables. Optimal sensor activity (current response) was obtained with a urease loading of 4 µl and ZnONPs concentration of 1.5 mg/L. For solution parameters, optimum pH was in the range of 7.0-7.5, optimum temperature was 35^oC, optimal substrate concentration 40 µl. Evaluation of some key biosensing properties revealed relatively stable biosensor activity within the first 7 days, good reproducibility with an RSD of 3.61%. Limits of detection (LOD) for the biosensor ranged from 0.04 – 0.07 while limits of quantitation (LOQ) ranged from 0.22- 0.13 ppm. Applying the developed biosensor to real samples was evaluated by analysing water samples from Kasuwangada River in Mubi North Local Government Area. The system showed good percentage recovery of the added heavy metal standard (0.05 – 0.25 ppm). Percentage recovery within the acceptable range of 98.00% to 103.00% was observed for Pb²⁺, 92.00% – 102.00 % recovery for Cr³⁺. Analysis of real samples and assessment of obtained results against a standard method (AAS) showed minimal differences. The developed biosensor showed sufficient sensitivity to the analysed sample and gave quantitative information on the Pb²⁺ and Cr³⁺content of the sample.

Keywords: Biosensor, Heavy Metals, Urease enzymes, Inhibition studies, Enzyme activity

CITE AS: Maitera O.N, Buba M, and I.I Nkafamiya (2024). Development of Amperometric Enzyme Biosensor for Determination of Heavy Metal Ions in aqueous samples. IDOSR JOURNAL OF EXPERIMENTAL SCIENCES 10(2) 45-59. https://doi.org/10.59298/IDOSR/JES/102.4559.1124