Chitosan Capped Silver Nanoparticles as Colorimetric Sensor for the Determination of Iron(III)

A selective, simple and low-cost method for the colorimetric determination of Fe3+ ions based on chitosan capped silver nanoparticles (Chit-AgNPs) was presented. Chitosan is a cationic polyelectrolyte and possesses amino and hydroxy groups which make it widely used as a capping agent for Ag NPs. The synthesized chitosan capped silver nanoparticles with excellent colloidal stability were characterized by UV–Visible spectrometry, transmission electron microscopy, Fourier transform infrared, X-ray diffraction. Chit-AgNPs exhibit a strong surface plasmon resonance band which disappears in the presence of increasing concentrations of Fe3+ ions. This system showed a visually detectable color change from brownish-yellow to colorless for the selective determination of Fe3+. The method can be applied for the determination of Fe3+ ions in the concentration range of 1.0×10-6 to 5.0×10-4 M. The detection limit was determined from three times the standard deviation of the blank signal (3σ/slope) as 5.3 × 10−7 M. The developed method was successfully applied for the determination of Fe3+in real samples