Development of Deep Eutectic Solvent Based Ferrofluid Liquid Phase Microextraction for the Determination of Ofloxacin in Egg and Milk Samples

A smart material based on ferrofluid deep eutectic solvents graphene oxide magnetite (MGO-DES FF) was successfully synthesized by adding choline chloride-thymol DES as carrier solvent onto MGO composite for the determination of ofloxacin in egg and milk samples. The synthesized materials were characterized using Fourier transform-infrared spectroscopy (FTIR), transmission electron microscopy (TEM), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and vibration sample magnetometer (VSM) to evaluate their functional groups, morphological and magnetic properties, respectively. The MGO-DES FF material was used as ferrofluid sorbent for liquid phase microextraction (LPME) of ofloxacin prior to UV–Vis spectrophotometry analysis. Several parameters were optimized including the type of DES, ferrofluid composition, ferrofluid volume, desorption solvent type and volume, pH, and extraction time to study their effects on the recovery percentage of ofloxacin. Under optimum conditions, good linearity was achieved between the range of 1 – 10 mg L⁻¹ for ofloxacin and a correlation coefficient of 0.9963. The LOD and LOQ values recorded were 0.75 and 1.55 µg L⁻¹, respectively. The RSD% for intra-day and inter-day were 2.64 and 7.40, respectively. The recovery percentage for milk and egg samples was ranging from 80.8 to 92.0%. Based on the results obtained, the developed MGO-DES FF LPME method demonstrated excellent sensitivity and efficiency for the extraction of ofloxacin in food samples. It showed great potential as an alternative method for the extraction of pharmaceutically active contaminants in the challenging matrix.