POTENTIOMETRIC DETECTION OF AMMONIUM ION IN SOIL SAMPLES OF ROHTAK BY DEPOSITION OF UREASE NANOPARTICLES ONTO PTFE MEMBRANE ON AMMONIUM ION SELECTIVE ELECTRODEBINDU, NAVEENA DINODIA, VIKAS ABROL AND SEEMA KUMARIAbstract The present study focuses on the urease nanoparticles preparation by desolvation method functionalized by cysteamine dihydrochloride and characterization of UrsNPs potentiometric biosensor for detecting ammonium ions level in soil. The biosensor was prepared by immobilizing these nanoparticles onto an activated PTFE membrane and bounded it with an ammonium ion selective electrode (AISE). Characterization of UrsNPs and immobilization onto PTFE membrane was done by Fourier transform infrared spectroscopy (FTIR) and field emission scanning electron microscopy (FESEM) techniques, which reveals nanoparticle diameters ranging from 13nm to 90nm.The ENPs were more active and stable with a longer shelf life than native enzyme molecules. The ENPs were immobilized onto chitosan (CHIT) activated PTFE membrane via glutaraldehyde coupling with 86.71% retention of initial activity of free urease NPs with a conjugation yield of 1.64 mg/cm2. This membrane was mounted at the lower end of the ammonium ion selective electrode (AISE) with O-ring and then electrode was connected to a digital pH meter to construct a potentiometric urea biosensor. The biosensor exhibited optimum response within 10 s at pH 5.5 and 40 °C. The biosensor exhibited potentiometric responses of NH4 + in soil samples with linear detection range of concentration between 0.01-0.80mM, low detection limit of 0.005mM respectively and sensitivity rate with a slope of 38mV/decade. Analysis of the additional urea revealed that the following percentages were recovered 107.4%. Due to very negligible amount of urea present in the aqueous solution of soil, the values did not changed and exhibited nearly 0.9830 % coefficient of variation for both with and within the samples. The maximum concentration of ammonium ion in the soil of village Ningana, 0.009ppm. Furthermore, the biosensorâs application enabled a comprehensive assessment of ammonium ion levels in diverse communities. The within and between-batch coefficient of variations (CVs) of present biosensor were 0.18% and 0.32% respectively. The biosensor had negligible interference from Cu2+, Ag+, Ni+ and Hg+ had slight interference, which was overcome by specific ion selective electrode. The ENPs bound NC membrane was used maximally 8â9 times per day over a period of 180 days, when stored in 0.01M sodium acetate buffer pH 5.5 at 4 °C. |