Growing concerns about the possible toxicity of silver to aquatic organisms, bacteria, and humans have led to newly issued regulations by the United States Environmental Protection Agency (US EPA) and the Food and Drug Administration (FDA) regarding the use of silver. However, the increase in bacterial resistance to antibiotics has led to a resurgence in the use of silver as a biocidal agent in applications ranging from washing machine additives to the drinking water treatment system on the International Space Station (ISS). For Ag + ion detection, a highly sensitive and reversible optical sensor has been established. The optode relies on a novel Schiff base, namely 2-[(benzo[d]thiazol-2-ylimino)methyl]phenol (BTMP) immobilized within PVC film and also incorporated with tris(2-ethylhexyl)phosphate (TEHP) and Aliquat 336 as an ion carrier. Under optimum conditions (i.e. pH 8.5), the proposed sensor displayed a linear response to Ag + over 4.8 Â 10 À9 to 1.0 Â 10 À5 M (0.8494-1698.7 mg L À1) with limits of detection and quantification of 1.5 Â 10 À9 and 4.8 Â 10 À9 M (0.2548 and 0.8494 mg L À1), respectively. The sensor's response time was found to be 8.0 min. The sensor was applied successfully to determine Ag + ion in some real samples, including food, biological, water, and environmental samples.