Preconcentration of Cd(II) by chemically converted graphene sheets adsorbed on surfactant- coated C18 before determination by flame atomic absorption spectrometry (FAAS)

A simple, highly sensitive, accurate and selective method for determination of trace amounts of Cd(II) in water samples is presented. A novel chemically converted graphene sheets (CCG) solid-phase extraction adsorbent was synthesized by CCG sheets. The stability of a CCG especially in concentrated hydrochloric acid was studied which used as a recycling and preconcentration reagent for further uses of CCG. The method is based on CCG of Cd(II) on surfactant-coated C18, modified with a CCG. The retained ions were then eluted with 4 ml of 4 M nitric acid and determined by flame atomic absorption spectrometry (FAAS) at 283.3 nm for Cd. The influence of flow rates of sample and eluent solutions, pH, breakthrough volume, effect of foreign ions on chelation and recovery were investigated. 1.5 g of surfactant-coated C18 adsorbs 40 mg of the Schiff’s base which in turn can retain 15.2 ± 0.8 mg of each of the two ions. The limit of detection (3σ) for Cd(II) was found to be 3.20 ng L-1. The enrichment factors for both ions are 100. The mentioned method was successfully applied on determination of Cd in different water samples. The ions were also speciated by means of three-column system. Key words: Determination of Cd, preconcentration, chemically converted graphene sheets (CCG), flame atomic absorption spectrometry (FAAS).