title: Biosensor based on glutamate dehydrogenase immobilized in chitosan for the determination of ammonium in water samples.
abstract: An optical biosensor based on glutamate dehydrogenase (GLDH) immobilized in a chitosan film for the determination of ammonium in water samples is described. The biosensor film was deposited on a glass slide via a spin-coating method. The ammonium was measured based on beta-nicotinamide adenine dinucleotide (NADH) oxidation in the presence of alpha-ketoglutaric acid at a wavelength of 340 nm. The biosensor showed optimum activity at pH 8. The optimum chitosan concentrations and enzyme loading were found to be at 2% (w/v) and 0.08 mg, respectively. Optimum concentrations of NADH and alpha-ketoglutaric acid both were obtained at 0.15 mM. A linear response of the biosensor was obtained in the ammonium concentration range of 0.005 to 0.5 mM with a detection limit of 0.005 mM. The reproducibility of the biosensor was good, with an observed relative standard deviation of 5.9% (n=8). The biosensor was found to be stable for at least 1 month when stored dry at 4 degrees C.
authors.affiliation: School of Chemical Sciences and Food Technology, Faculty of Sciences and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor D.E., Malaysia.
authors.forename: Nur Ellina
authors.initials: NE
authors.lastname: Azmi
authors.forename: Musa
authors.initials: M
authors.lastname: Ahmad
authors.forename: Jaafar
authors.initials: J
authors.lastname: Abdullah
authors.forename: Hamidah
authors.initials: H
authors.lastname: Sidek
authors.forename: Lee Yook
authors.initials: LY
authors.lastname: Heng
authors.forename: Nadarajah
authors.initials: N
authors.lastname: Karuppiah
mesh_terms: D015374:Biosensing Techniques / Q000379:methods*; D048271:Chitosan / Q000737:chemistry*; D004800:Enzymes, Immobilized / Q000737:chemistry / Q000378:metabolism; D005969:Glutamate Dehydrogenase / Q000737:chemistry* / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007656:Ketoglutaric Acids / Q000737:chemistry; D009243:NAD / Q000737:chemistry; D010084:Oxidation-Reduction; D000644:Quaternary Ammonium Compounds / Q000032:analysis*; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000737:chemistry
chemical_list: D004800:Enzymes, Immobilized; D007656:Ketoglutaric Acids; D000644:Quaternary Ammonium Compounds; D014874:Water Pollutants, Chemical; D009243:NAD; D048271:Chitosan; D005969:Glutamate Dehydrogenase