An innovative environmentally-friendly optical sensor utilizing sol-gel method for thorium detection in environmental samples

Introducing a cutting-edge technique, we have harnessed the exceptional properties of 1-(2-arsonophenylazo)2-naphthol (APAN) as a highly sensitive reagent, expertly immobilized within a sol-gel thin film. Our revolutionary optical test strip now enables swift and accurate detection of Th(IV) in aqueous solutions, eliminating the need for cumbersome extraction processes. A comprehensive exploration of vital experimental parameters, including membrane composition, pH variations, and the type and concentration of regenerating reagents, has been meticulously undertaken to optimize performance. Innovatively designed with a square-sensing zone measuring 1.0 cm × 1.0 cm, our test strip encompasses the essential APAN reagent, capable of promptly responding to even minute traces of thorium. The dynamic response exhibited a remarkable linearity within the Th(IV) concentration range of 10–235 ng ml⁻¹, granting calculated detection and quantification limits of 3.0 and 9.9 ng ml⁻¹, respectively. A mere 3-min response time, coupled with the ideal pH of 3.25, contributes to unparalleled measurement repeatability and sensor-to-sensor reproducibility, exemplifying the excellence of our methodology with a mere 1.75% relative standard deviation (RSD). Our unwavering commitment to selectivity shines through in comprehensive interference investigations, showcasing the proficient trapping of APAN within the sol-gel matrix, deftly tailored for Th(IV) assessments. The sensor’s prowess surpasses its contemporaries, confidently validated in discerning Th(IV) levels across diverse environmental samples, rendering satisfactory outcomes. In the pursuit of innovation, our novel approach exemplifies a harmonious blend of professionalism and creativity, promising transformative advancements in Th(IV) detection methodologies.