Synthesis of Silver Nanoparticles-Agarose Composite and Its Application to the Optical Detection of Cyanide Ion.

Abstract

A highly sensitive and selective colorimetric method was developed for the detection of CN- ion based on the surface plasmon resonance of silver nanoparticles (AgNPs) embedded in a transparent agarose matrix. The AgNPs were prepared by chemical reduction of Ag+ in the presence of sodium borohydride as the reducing agent and agarose as the stabilizing agent. Characterization of the nanoparticles was performed with UV/Vis spectrometry and scanning electron microscopy. A calibration curve was derived for the absorbance of the sensor at 410 nm, that was linear over a range from 1.5 to 120 μmol L-1 with an R2 value of 0.998 (n = 8). A detection limit of 0.69 μmol L-1 and a relative standard deviation of 3.8% were obtained for CN- for 8 replicates. A reproducibility of about 6.1% was also obtained for four batches of the sensor. The sensor showed excellent selectivity for CN- ion at the presence of a number of interfering ions with concentrations exceeding 50 times of that of the analyte. The results showed successful application of the AgNPs-agarose as a colorimetric sensor for easy and selective monitoring of CN- ion in aqueous solutions.