One-step preparation of functional groups-rich graphene oxide and carbon nanotubes nanocomposite for efficient magnetic solid phase extraction of glucocorticoids in environmental waters

Efficient capture of glucocorticoids (GCs) at ultra-trace levels in environmental waters is not an easy task due to the abundant hydrophilic groups in their molecules and complexity of sample matrices. In this study, by means of one-step hydrothermal strategy, a functional groups-rich magnetic nanocomposite (MNC) was prepared using amino-derivatized carbon nanotubes and 1-formylimidazole modified graphene oxide as functional reagents. The characterization results indicated that the obtained nanocomposite displayed satisfying saturation magnetism and could be employed to quickly extract GCs under the format of magnetic solid phase extraction (MSPE). In addition, the prepared MNC presented notable capture ability to studied GCs through multiple interactions such as pi-pi, hydrophobic, H-bonding and dipole-dipole forces. Under the optimized parameters, highly sensitive method based on MNC/MSPE and high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was developed to quantify ultra-trace levels of GCs in a variety of environmental waters. Low limits of detection (0.0075-0.16 ng/L), wide linearity (0.05-1000 ng/L) and excellent precision (RSDs < 10%) were achieved. The possible extraction mechanism was also investigated. Combining with isotope internal standard calibration curve approach, the suggested MNC/MSPE-HPLC-MS/MS approach was applied to measure low contents of thirteen GCs in river water, lake water, sea water and effluent from treatment plant, and good fortified recoveries (79.7-120%) and reproducibility (RSDs below 10%) were obtained.