Optimization of Castor Oil-Based Ion Selective Electrode (ISE) with Active Agent 1,10-Phenanthroline for Aqueous Pb(2+) Analysis

This research has successfully fabricated ion selective electrode (ISE) for Pb(2+) using castor oil (Ricinus communis L.)-based polyurethane (PU) membrane with 1,10-phenanthroline as the active agent. The sensitivity of the Pb(2+) ISE obtained is 27.25 mV/decade with a linear range of [Pb(NO(3))(2)] of 10(−10)–10(−5) M and a coefficient of determination (R(2)) of 0.959. The system response reaches stability after 25 s of measurement. The Pb(2+) has a detection limit of 10(−10) M and gives a stable response at pH 7–8 with a 15-day lifetime. The investigation of the selectivity of the ISE was performed using the mixed solution method with log Kij values of <1. The selectivity order of Pb(2+) ISE against the foreign ions is Ag(2+) > Ca(2+) > K(+) > Mg(2+) > Cu(2+) > Fe(3+) > Cr(3+)> Zn(2+) > Cd(2+). The Pb(2+) ISE shows acceptable reproducibility and repeatability with standard deviation values of 0.065 and 0.0079, respectively. Fourier transform infrared (FT-IR) spectra confirmed that 1,10-phenanthroline was responsible for the formation of the Pb(2+) ion entrapment via complexation. Other characterizations (crystallinity, micro-surface morphology, and mechanical strength) suggest the degradation of the membrane structure integrity after the application. The analysis results of Pb levels using the Pb(2+) ISE in artificial and wastewater samples were not significantly different from the atomic absorption spectroscopy (AAS) measurement.