Resources and Environment

## Application of graphene in needle trap device for pretreatment of aqueous samples followed by gas chromatographic analysis

Kamila Kędziora-Koch and Wiesław Wasiak

Department of Chemistry, Adam Mickiewicz University in Poznan, Umultowska 89b, 61-614, Poznan, POL

Graphene (G) is a form of carbon-based material, which possesses a single layer of carbon atoms arranged in a honeycomb two dimensional lattice. Due to its prominent properties, G has attracted much interest in analytical chemistry recently. In comparison with the other carbon allotropes, graphene has a large specific surface area (theoretical value 2630 m2/g), suggesting a high adsorption capacity. Additionally, both sides of its planar sheets are available for molecule adsorption. Another advantage of G is the large delocalized $\pi$-electron system which provides a strong affinity to aromatic rings of organic compounds. Graphene may be also easily functionalized, which allows manipulations of the adsorption selectivity 1

The aim of this work was application of graphene in the sample preparation technique named needle trap device (NTD) and determination the efficiency of the extraction system filled with G towards polycyclic aromatic hydrocarbons (PAHs).

The needle trap extraction device consists of the glass syringe connected to an extraction needle filled with the sorbent. Extraction is performed by drawing the sample inside the needle and then desorption take place. Afterwards, the analytes are analyzed using chromatographic methods 2. In our work, graphene was immobilized inside the needle with the use of glass wool. The mass of the supporting layers (glass wool) and the mass of graphene were optimized in order to prevent the sorbent escape and to overcome the flow resistance.

The physicochemical properties of used graphene were characterized via elemental analysis, low-temperature N2 adsorption-desorption measurements and scanning electron microscopy (SEM). Then, the extraction procedure of PAHs with the use of G-NTD was optimized and evaluated. The obtained results showed that needle trap device filled with graphene is good sample preparation technique used for enrichment the target compounds before gas chromatographic analysis. Additionally, comparison of G-NTD with the other sorbents packed in the NTD (activated carbon and C18 silica) revealed that more effective sorbent was graphene which was also reusable and did not cause the flow restrictions during analytical procedure.

1. B.-T. Zhang, X. Zheng, H.-F. Li, and J.-M. Lin, “Application of carbon-based nanomaterials in sample preparation: A review,” Anal. Chim. Acta, vol. 784, pp. 1–17, 2013.

2. K. Kędziora and W. Wasiak, “Extraction media used in needle trap devices—Progress in development and application,” J. Chromatogr. A, vol. 1505, pp. 1–17, 2017.