Raman transduction for polymeric ion-selective sensor membranes: Proof of concept study

A novel technique for indirect metal ions detection with micro-Raman spectroscopy is proposed. Plasticized polymeric membranes typically applied for construction of ion-selective electrodes were employed to obtain Raman spectra as analytical signal. The latter is derived from evolution of Raman spectrum of lipophilic ligand incorporated into sensor membrane upon a contact with sample solutions. It is demonstrated that the membrane Raman spectrum depends on the metal concentration in sample solution. This is due to the metal binding by ligand at the membrane surface. Moreover, the observed spectral changes can be related to metal content through multivariate modelling (partial least squares regression). This feasibility study opens a potentially new field consisting of the application of micro-Raman spectroscopy for indirect analysis of ions in micro volumes of the samples (10 μL).