Biosensor based on glutamate dehydrogenase immobilized in chitosan for the determination of ammonium in water samples.
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.
Azmi
Nur Ellina
NE
School of Chemical Sciences and Food Technology, Faculty of Sciences and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor D.E., Malaysia.
Ahmad
Musa
M
Abdullah
Jaafar
J
Sidek
Hamidah
H
Heng
Lee Yook
LY
Karuppiah
Nadarajah
N
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
D004800:Enzymes, Immobilized; D007656:Ketoglutaric Acids; D000644:Quaternary Ammonium Compounds; D014874:Water Pollutants, Chemical; D009243:NAD; D048271:Chitosan; D005969:Glutamate Dehydrogenase