Optical constants of a sodium alginate polymer in the UV–vis range

The dispersive refractive index and the thickness of alginate polymer films have been obtained by using the envelope-extremes location technique. The uncertainty in the determination of the refractive index is of the order of 0.01. The alginate polymer has been prepared with a solution of sodium alginate with a concentration of 0.7% in weight, mixed with a 0.03 M solution of CaCl2. Since the main application of this kind of polymers is the immobilization of living organism for biosensors, especially those based on fluorescence measurements, we focus the analysis in the ultra-violet–visible (UV–vis) spectral range.