Evaluation of three dimensional high nitrogen doped graphene as an efficient sorbent for the preconcentration of BTEX compounds in environmental samples

Abstract

Introducing a new class of sorbents is an interesting study especially in the field of sample preparation. In this study, for the first time, three-dimensional high nitrogen doped graphene (3D-HND-G) was synthesized as a new sorbent and then it was successfully applied for the quantification of BTEX compounds in environmental samples using gas chromatography. First, the extraction efficiency of various carbon nanostructures, including graphene (G), graphene oxide (GO), nitrogen doped graphene (ND-G), high nitrogen doped graphene (HND-G), and 3D-HND-G, were compared. The results revealed that 3D-HND-G had higher efficiency for the extraction of BTEX compounds. Better dispersibility and higher surface area of 3D-HND-G rather than other carbon nanostructures may be the main reason for this phenomenon. Box–Behnken design methodology and response surface methodology were applied to determine the optimal experimental conditions. The optimized extraction conditions were as follows: sorbent amount, 70 mg; sorption time, 8 min; salt concentration, 6.5% w/v; and type and volume of the eluent, 255 μL methanol. Under the optimized conditions, the enrichment factors were obtained within the range of 328–376, which corresponds to extraction recoveries of 82%–94%. The limit of detection and quantification was in the range of 0.5–1 ng mL⁻¹ and 1.5–3 ng mL⁻¹, respectively. The method was reproducible since the intra and inter day precisions (RSDs%, n = 5) were less than 6.2%. Finally, the proposed method was successfully applied to determine the concentration of BTEX as hazardous materials in environmental samples.