Development Of A Cobalt (ii) Optical Sensing Film Based On N~5-(2,4-dinitro-phenyl)-n~1,n~1-diethyl-penta-1,3-diene-1,5-diamine

摘要

An optical sensing film has been proposed for sensitive determination of cobalt (Co) (II) ion in aqueous solutions. The cobalt sensing membrane was prepared by incorporating N~5-(2,4-dinitro-phenyl)-N~1,N~1-diethyl-penta-1,3-diene-1,5-diamine (HDDA) as ionophore in the plasticised PVC membrane containing o-nitro-phenyl octyl ether as plasticiser. The membrane responds to cobalt ion by changing colour irreversibly from yellow to green in acetate buffer solution at pH = 5.5. The proposed sensing film displays a linear range of 0.028-29.68 μg mL~(-1) with a limit of detection 0.012 μg mL~(-1). Moreover, upon the introduction of a negatively charged lipophilic additive (oleic acid) into the membrane, the optode displayed enhanced sensitivity. In addition, satisfactory analytical sensing characteristics for determining Co(II) ion were obtained in terms of the selectivity, stability and reproducibility. The response time of the optode was about 15-25 min, depending on the concentration of Co(II) ions. The optode membrane has been applied to determine Co(II) in various water samples and copper-free alloys.