Solid-phase dispersive microextraction using reduced graphene oxide for the sensitive determination of cadmium and lead in waters

A graphene oxide suspension is treated with sodium citrate in the presence of silver ions, and then nanoparticles of the composite containing reduced graphene oxide and metallic silver are obtained. A small amount (0.1 mg) of this material is dispersed into a liquid sample (10 mL) at pH 8 allowing very small amounts of cadmium and lead to be retained. The separation of the solid phase is carried out by means of a cloud point extraction process using Triton X-114. Lead and cadmium are then measured in the surfactant-rich phase by electrothermal atomic absorption spectrometry. The enrichment factor is 105 which provides detection limits of 2 and 30 ng L-1 for cadmium and lead, respectively. The relative standard deviations calculated for six measurements at three concentration levels are in the 3.7-4.5% range. The reliability of the procedure is verified by analysing six water samples with certified cadmiumand lead contents.