Deep eutectic solvent loaded onto graphene oxide as a novel phase for pipette-tip micro-solid phase extraction of levofloxacin from seawater and body fluid samples
Jasem Jangizahi, Sayyed Hossein Hashemi
Abstract
In this research, applicability of an environmentally friendly deep eutectic solvent (DES) for pipette-tip micro-solid phase extraction and preconcentration of levofloxacin prior to its quantification by spectrophotometry at the wavelength of 240 nm is presented. Carvone:thymol (1:1 molar ratio) DES was prepared and coated on graphene oxide and applied as adsorbent. This adsorbent was characterised utilising Fourier transform infrared and field emission scanning electron microscopy, which showed a uniform layer of DES coated on graphene oxide. 5.0 mg of this adsorbent was packed into a 100 µL pipette-tip and was applied to miniaturised pipette-tip solid-phase extraction of levofloxacin. Parameters affecting microextraction including kind and volume of elution solvent, pH, amount of sorbent, sample volume, and number of aspirating/dispensing cycles were investigated and optimised using one-variable-at-a-time procedure, central composite design, and Box-Behnken design response surface methodologies. The developed method required only 5.0 mg of adsorbent and 150 µL of methanol:acetone (2:1) (elution solvent) to achieve a low detection limit of 0.3 µg/L with a linear range of 1–500 µg/L. High enrichment factor of 65.3 with a good precision (RSD ≤ 4.7%) was also achieved. The proposed method was successfully applied to determine levofloxacin in pills, blood, urine and a few seawater samples.