Author(s)

Nur Ellina Azmi, Jaafar Abdullah, Musa Ahmad, Hamidah Sidek, Lee Yook Heng, Samsulida Abd Rahman

Industrial Biotechnology Research Centre, SIRIM Berhad, Shah Alam, Malaysia.
Industrial Biotechnology Research Centre, SIRIM Berhad, Shah Alam, Malaysia..
School of Chemical Sciences and Food Technology, Faculty of Sciences and Technology, Universiti Kebangsaan Malaysia, Bangi, Malaysia..
School of Chemical Sciences and Food Technology, Faculty of Sciences and Technology, Universiti Kebangsaan Malaysia, Bangi, Malaysia..

A simple and rapid optical biosensor for the determination of ammonium was developed by immobilization of gluta-mate dehydrogenase (GLDH) and diaphorase (Dph) in chitosan film coated on a glass slide employing thiazolyl blue tetrazolium bromide (MTT) as a color indicator. The developed biosensor displays a purple color formation of formazan attributed to the unreacted NADH in the reaction system in the presence of ammonium. The color intensity was found to decrease proportionally with the increase of ammonium concentrations after 10 min exposure. The linearity of the biosensor towards ammonium was in the range of 16.8 – 70 μM (R2 = 0.9955) with detection limit of 11 μM. A good agreement (R2 = 0.9984) with indothymol method was obtained in the measurement of fish pond water samples. The effect of potential interferences such as metals ion has also been evaluated.

Optical Biosensor; Glutamate Dehydrogenase; Diaphorase; Ammonium

N. Azmi, J. Abdullah, M. Ahmad, H. Sidek, L. Heng and S. Rahman, "An Optical Based Biosensor for the Determination of Ammonium in Aqueous Environment," American Journal of Analytical Chemistry, Vol. 3 No. 5, 2012, pp. 364-370. doi: 10.4236/ajac.2012.35048.