Silver nanoparticles (AgNPs) were prepared by using the chemical and biological reduction methods with the aid of tri sodium citrate and the aqueous extracts of plant leaves. All nanoparticles obtained revealed the Surface Plasmon Resonance (SPR) band at around 400 nm. Fourier Transform Infrared spectroscopy of nanoparticles exposed the presence of phenol and amine compounds that are responsible for the reduction of metal ions. SEM with EDAX data and DLS measurements has confirmed the mono dispersity and spherical nature of the AgNPs. Stability of the nano dispersion was confirmed from the absence of red shift in the LSPR band after three months of incubation at room temperature. Aqueous Zn2+ and Cu4+ ions selectivity and sensitivity study of these chemical and green synthesized nanoparticles was performed based on the Surface Plasmon Resonance (SPR). Addition of increasing concentration of zinc and copper metal ions to the colloidal dispersion, led to the prominent red shift of the Surface Plasmon Resonance band of AgNPs. Sensitivity of the AgNPs from Balanites aegyptiaca towards both the ions remains significant and hence, there application as an optical sensor would be helpful to environmental applications such as metal ion detection. Copyright © 2014 American Scientific Publishers