Sharma Harish K, Verma Neha and Kapoor J. K.
La(III) selective electrodes have been prepared by using 2-Hydroxy-N-(2’-hydroxyphenyl) benzalideneimine (as I) and 5-Bromo-2-hydroxy-N-(2’-hydroxyphenyl) benzalideneimine (as II) as electro active materials and epoxy resin as a binding material. The electrodes were prepared with composition 50% electro active material and 50% binder. An excellent response was shown by (I) in the concentration range of 10-6 M - 10-1 M La (III) ions with a sub Nernstian slope of 14 mV/decade. It has a fast response time of 10 seconds and can be used for at least six months without any considerable potential divergence. The response shown by electrode (II) was also in the concentration range of 10-6 M - 10-1 M La (III) ions with a sub Nernstian slope of 7 mV/decade. It also has a fast response time of 10 seconds and can be used for at least four months without any considerable potential divergence. Effect of internal solution has been studied and the electrodes were successfully used in partially non-aqueous medium, too. Selectivity coefficients have been determined by FIM method, with respect to alkali, alkaline earth, some transition and rare earth metal ions. Electrode (I) can be used in the pH range of 2.85-7.5 and electrode (II) shows pH range of 2.9-8.9. Both the electrodes have been used as indicator electrodes in the potentiometric titration of La (III) ions against Tartaric acid.
