Evaluation of Graphene as a Solid-Phase Extraction Sorbent for the Preconcentration and Determination of Trace Amounts of Nickel in Food Samples Prior to Flame Atomic Absorption Spectrometry.

A sensitive and low cost SPE method for the extraction, preconcentration, and flame atomic absorption spectrometric determination of nickel at ng/mL levels is described. Parameters governing the extraction efficiency including pH of the solution, eluent type, sample volume, and matrix ions were investigated for optimization of the presented procedure. The enhancement factor was calculated as 96.5. The calibration curve was linear with R2 of 0.999 in the concentration range from 2 to 200 ng/mL. The RSD was 5.35% (n=7), the LOD was 0.588 ng/mL, and relative recoveries from vegetable samples ranged between 99 and 109.5%.