Highly selective silver nanoparticles based label free colorimetric sensor for nitrite anions

Highly selective label free colorimetric sensor based on AgNPs stabilized by phenolic chelating ligand, N, N'-bis(2-hydroxybenzyl)-1,2-diaminobenzene (1), for NO2 anions has been developed. Addition of NO2 showed selective decolourisation of brownish yellow colour of 1-AgNPs with the detection limit of 10(-7) M. Absorption studies showed the complete disappearance of 1-AgNPs peak at 426 nm due to the conversion of AgNPs to silver ions. The presence silver ions were confirmed by white precipitates of AgCl formation with NaCl. The interference studies confirmed the high selectivity of NO2 sensing in presence of anions as well as cations by 1-AgNPs. A linear relationship was observed between the change of absorption and concentration of NO2. The present approach could be performed at room temperature and ambient conditions. The practical applications of 1-AgNPs for selective sensing of NO2 in different water samples such as ground, river, pond and tap water have also been demonstrated. (C) 2014 Elsevier B.V. All rights reserved.