Nanosilver cotton swabs for highly sensitive and selective colorimetric detection of sulfide ions at nanomolar level.

Herein, we report a simple and rapid method for the visual detection of sulfide ion in an aqueous environment with high sensitivity and specificity by using ciprofloxacin capped silver nanoparticles (Cip-AgNPs). The sensor system can be used to detect as low as 16 nM of S 2− in aqueous environment by only naked-eye and 0.112 nM of S 2− by absorption spectrophotometer. The visual detection limit of 16 nM is much lower than the maximum allowable level of S 2− (15 μM) in the drinking water defined by the world health organisation. The proposed sensor detects S 2− at a wide range of pH and also demonstrated to sense S 2− in tap water and river water, with good recovery. For portable use, we synthesized highly stable Cip-AgNPs on cotton and demonstrated good sensitivity against S 2− ion. As prepared Cip-AgNPs embedded cotton detects S 2− in an aqueous solution and S 2− in a gaseous state, indicating that our sensor meets the requirement for on-site detection of S 2− in the environment by only-naked eye. [ABSTRACT FROM AUTHOR]