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.