Application of graphene as a sorbent for preconcentration and determination of trace amounts of chromium(III) in water samples by flame atomic absorption spectrometry

Graphene, a novel class of carbon nanostructure, has great promise for use as a sorbent material because of its ultrahigh specific surface area. A new method using a column packed with graphene as sorbent is developed for the preconcentration of trace amounts of chromium(III) prior to its determination by flame atomic absorption spectrometry. Some effective parameters on the extraction and complex formation were selected and optimized. The optimum experimental conditions of the proposed method were: pH, 8.0; amount of chelating agent, 2.0 mL of 0.1 mol L-1 8-hydroxyquinoline solution; eluent type and its volume, 2.0 mL of 2.0 mol L-1 nitric acid; flow rates of sample and eluent solution, 2.0 mL min(-1). Under optimum conditions, an enrichment factor of 125 was obtained. The calibration graph was linear in the concentration range of 10.0-1000.0 mu g L-1 with a correlation coefficient of 0.9995. The detection and quantification limits were 0.5 and 1.6 mu g L-1, respectively. The relative standard deviation for ten replicate measurements were 4.3% for 20.0 mu g L-1 and 3.4% for 800.0 mu g L-1 of Cr(III). The proposed method was applied to tap water, sea water, and river water, and its accuracy was assessed through the analysis of certified reference water and recovery experiments. The recoveries of spiked samples were in the range of 95.7-101.2%.