Silica nanoparticle-covered Graphene Oxide as solid-phase extraction sorbent coupled with FAAS for the determination of some of heavy metals in water sample

The current study portrays a dispersive solid-phase extraction as a silica nanoparticle-covered Graphene Oxide(GO-SiO2) synthesised with some modification as in the literature and developed removal/preconcentration method for selective extraction of some heavy metal in water samples. Flame atomic absorption spectrophotometry (FAAS) was used to measure in optimum conditions for the proposed method. Field emission scanning electron microscope (FESEM) and X-beam diffraction (XRD) were utilised for the characterisation of solid phase. The developed method presents high surface areas for sorption capacity and a low amount of solid phase. The removal percentage was performed at approximately 100% with pH 4 to 10 for all metal ions. According to validation results under the optimised method, the limits of detection (LODs) and quantification (LOQs) were found in the range of 5.8-23.0 mu g L-1 and 16.0 - 38.1 mu g L-1, respectively. The developed method was applied by using certified reference material (BCR 715) for trueness, which observed high relative recovery with lower than 11.8% relative error except for Pb and Cd. The comparison between the experimental results and the certified reference material indicated that the accuracy of the method is higher than 90%. The proposed method was effectively practised for five water samples with standard addition.

Automated summary

The study developed a modified solid phase material with graphene oxide-covered silica nanoparticles for selective extraction of heavy metals in water samples. The method showed high sorption capacity and low solid phase amount, achieving approximately 100% removal rate over a wide pH range. Validation tests demonstrated the high accuracy of the method, exceeding 90%.