Surface plasmon resonance optical sensor for detection of Pb2+ based on immobilized p-tert-butylcalix[4]arene-tetrakis in chitosan thin film as an active layer

Surface plasmon resonance (SPR) optical sensor, for sensitive and selective detection of Pb2+, was developed in this study based on p-tert-butylcalix[4]arene-tetrakis (BCAT) immobilized in chitosan thin film as an active layer. Pb2+ can be detected by measuring the SPR signal when BCAT immobilized chitosan thin film is exposed to Pb2+ in aqueous solution. The BCAT immobilized chitosan thin film was coated on a gold layer by spin coating technique. The measurements were carried out for Pb2+ concentration ranging from 30 ppb to 5 ppm. A linear relationship between the shift of SPR angle and concentration of Pb2+ up to 1 ppm, with sensitivity of 0.045° ppm−1 has been observed. Pb2+ can also be selectively detected when present in mixtures of heavy metal ions containing Cu2+, Hg2+, Zn2+ and Mn2+ ions.