Abstract

The presence of heavy metal ions in contaminated water is creating lots of heath damage in livings species in last few decades. Most commonly used heavy metal ions are Cu⁺², Ni⁺², Pb⁺²… etc. Taking into account of above, the detection of lead ions (Pb⁺²) ions in contaminated water is important [1]. Molecular imprinting is a method used for the selective identification of templates. It creates binding sites or nano cavities in polymer which has complementary shape and size of the templates and recognizes the template molecule by key and lock model [2]. It has been used along with surface plasmon resonance (SPR) for the confirmation of the binding of templates with the polymer. SPR is a phenomenon which allows the real time detection of bimolecular interaction with the help of a p-polarized light. A sharp dip in transmittance spectra at a particular wavelength, called resonance wavelength, has been observed while satisfying resonance condition in SPR. If there exists a change in the dielectric nature of sensing medium, then a shift in resonance wavelength has been observed [3]. By measuring the shift we can observe the binding of template molecule with the polymer because the binding of template with the polymer produces the variation in the dielectric nature of the polymer. In the present study a preliminary study on the fabrication and characterization of a fiber optic sensor for the detection of Pb⁺² ions utilizing SPR and molecular imprinting has been reported. To fabricate molecularly imprinted polymer (MIP), Pb(NO₃)₂ is used as template molecule. When template molecule near the vicinity of the MIP, it binds with the imprinted sites which causes the shift in resonance wavelength is recorded while recording the SPR response of the fiber optic probe. The proposed sensor operates in the concentration range of 10^-9 M to 10^-4 M of Pb⁺² ions. The proposed sensor has various advantages such as low cost, fast response and capability of online monitoring and remote sensing.

© 2015 Japan Society of Applied Physics, Optical Society of America