Development of an innovative colorimetric optical sensor for the detection of silver ions in environmental and biological samples

Abstract

A recently developed optical chemical sensor for silver assessment relies on polymer inclusion membranes (PIM) and avoids the use of plasticisers. This innovative optical sensor is constructed through a physical immobilisation process known as the encapsulation technique, resulting in an optical chemical membrane. The suggested PIM integrates 2-(2`-hydroxynaphthylazo)benzo-thiazole (HNABT) was used as a colorimetric reagent, polyvinyl chloride (PVC) as the foundational polymer, and dinonyl naphthalene sulphonic acid (DNNS) as an extractant. The created PIM demonstrates heightened responsiveness within the described approach, credited to the sensor membrane, in contrast to the optical sensor without PIM. The achieved results demonstrated that the sensor response was based on some factors such as plasticiser, film thickness, stirring effect, HNABT concentration, DNNS concentration and pH of the aqueous solution. Within the measurement range spanning from 7.5 to 250 ng mL−1 of Ag+ at pH 7.75, the absorbance response exhibits a notable correlation, achieving detection and quantification limits of 2.3 and 7.3 ng mL−1, respectively. The λmax for the PIM-based sensor registers at 577 nm. Additionally, the reproducibility and repeatability of the system are characterised by RSD of 2.25% and 1.13%, respectively, with a swift response time of approximately 3.0 min. The optode membrane's selectivity is scrutinised in pH-buffered solutions concerning Ag+ ions. The proposed sensor is effectively applied for Ag+ assessment in food, water, environmental, and biological samples. The obtained results are corroborated by the FAAS procedure.