Eco-friendly optical sensor for detecting bismuth(III) ions in environmental, pharmaceutical, and biological sources

A highly responsive bulk optical sensor (optode) has been introduced for the detection of bismuth {Bi(III)}. This optode integrates sodium tetraphenylborate (NaTPB) and 2-(benzothiazolylazo)1,6-naphthalenediol (BTAND) into a plasticized polyvinyl chloride (PVC) membrane, incorporating o-nitrophenyl-octyl ether (o-NPOE) as a plasticizer. The influence of several variables was optimized, including pH, the solvent mediator base matrix, and the reagent concentration. The comparison of results with previously reported methods indicates that the proposed approach, characterized by its speed and simplicity, offers a low detection limit (2.25 ng/mL) and a favorable linear range (7.5–220 ng/mL). The sensor exhibited stability, remaining unchanged even after being stored for at least one month. The sensor was successfully regenerated using a 0.25 M nitric acid (HNO 3 ) solution, and it responded in a reversible manner with an RSD of less than 2.15% for six replicate measurements of 125 ng/mL of Bi(III) in different membranes. The capability to accurately and consistently monitor the quantity of Bi(III) ions in pharmaceutical and environmental samples with complex matrices is facilitated by the low detection limit and superior selectivity, despite the existence of interfering anions and cations. Representation for the preparation and complexation of the formed [Bi–(BTAND) 3 ] optode.