The graphene oxide/magnesium–aluminium bimetallic hydroxides composite used as solid-phase extractant for determination of monoaromatic hydrocarbons in wastewater

The graphene oxide (GO) and the magnesium–aluminium bimetallic hydroxides composite (GO/Mg-Al-LDH) was used as a solid-phase extractant for determination of toluene, ethylbenzene, p-xylene, m-xylene, o-xylene, 1,3,5-trimethylbenzene and 1,2,4-trimethylbenzene in wastewater by gas chromatography-mass spectrometry analytical method. When the amount of solid-phase extractant was 1.5 g, the extraction time was 6 min, and the elution with 2 mL of chloroform for 3 min, seven monoaromatic hydrocarbons (MAHCs) in 500 mL of water sample can be well extracted and separated. Under the optimised experimental conditions, the mass concentration of each component in the range of 0.01–5 ng/mL has a good linear relationship with the peak area, the coefficients of determination are all greater than 0.995. The relative standard deviation (n = 5) and the method detection limit range are 2.9–7.1% and 0.0005–0.005 ng/mL, respectively. The seven of MAHCs in Dongfengqu River and laboratory wastewater of Chengdu University of Technology can be effectively detected, the recovery rate and the relative standard deviation (n = 5) are 83.0–110.0% and 3.7–9.4%, respectively. For the first time, the GO/Mg-Al-LDH composite was used as a solid-phase extraction material, and seven MAHCs in water were successfully determined by GC-MS. The detection method is established with low detection limit and high reproducibility which can meet the measurement requirements of trace MAHCs in wastewater.