Hamed Azimi - Islamic Azad university, South Tehran Branch
Seyyed Hamid Ahmadi - Chemistry & Chemical Engineering Research Center of Iran
Mohammad Reza Manafi - Islamic Azad university, South Tehran Branch
Syed Hossein Hashemi Moosavi - Islamic Azad university, South Tehran Branch
Mostafa Najafi - Imam Hosein University

Nickel is a toxic transition metal which can create serious problems in health of humans and wildlife. Thus determination of nickel in environmental samples like waters is important and inevitable. In this research a simple and sensitive method for determination of nickel in water was described based on aggregation of citrate capped silver nanoparticles. Silver nanoparticles were prepared by reduction of silver nitrate with sodium borohydride. Cefixime was as chelating agent in the assay and when nickel was added to the mixture of citrate capped silver nanoparticles and cefixime, color of citrate capped silver nanoparticles changed from light yellow to red that depend on Ni۲+ concentration. As a result of aggregation, local surface plasmon resonance (LSPR) band of silver nanoparticles around ۳۹۵ nm decreased and a new peak appeared in ۵۵۰ nm. Control experiments with ۱۰ other ions carried out and did not a distinct change in color or spectrum. Under optimized conditions, linear relationship between Ni۲+ concentrations and the absorbance ratio of A۵۵۰/A۳۹۵ and limit of detection were found in the range of ۲.۷۰ µmol L-۱ to ۱۷.۱۰ µmol L-۱ and ۰.۸۰ µmol L-۱, respectively. The method was applied in tap and well waters that indicate the colorimetric method has acceptable accuracy and good stability.

Silver nanoparticle, Localized surface plasmon resonance, nickel, Colorimetric detection