Highly sensitive photoluminescence sensor based on chitosan biopolymer film for determination of hydrogen peroxide

Determination of hydrogen peroxide (H₂O₂) is of great importance in many systems for controlling the quality of products, food safety, and medical diagnostics. In this work, a highly sensitive photoluminescence film sensor was synthesized based on chitosan (CS), polyvinyl alcohol (PVA), and terephthalic acid (TPA), in the presence of copper (II) ions for determination of hydrogen peroxide. TPA was used as a sensitive probe for detection of hydroxyl radicals produced in a photo-Fenton-like process. Several important factors that can affect the fluorescence response of the sensor were investigated, including the irradiation time, pH, and the amount of catalyst. The response of the sensor (CS/PVA-Cu-TPA) was greatly improved by UV irradiation. The structure of the film sensor was studied by FT-IR, TGA, SEM, and X-ray mapping analysis. The highest response values were observed under the optimum conditions (0.7 % w/w Cu (II) ions, 4.25 % w/w TPA, 45 min UV irradiation, and excitation at 315 nm). This method can be applied for determination of H₂O₂ with a limit of detection (LOD) of about 0.1 μM and limit of quantification (LOQ) of about 0.33 μM. The practical value of the highly sensitive fluorescence sensor was illustrated by its application in milk samples.