Graphene oxide-based dispersive-solid phase extraction for preconcentration and determination of ampicillin sodium and clindamycin hydrochloride antibiotics in environmental water samples followed by HPLC-UV detection

In the present study, a reusable graphene oxide (GO) based dispersive-solid phase extraction (d-SPE) was synthesized and applied for the analysis of trace ampicillin sodium (AMP) and clindamycin hydrochloride (CLI) in water samples followed by high performance liquid chromatography-UV detection (HPLC-UV). Batch experiments were conducted to investigate the effects of pH and volume of the sample solution, contact time, adsorption isotherms, temperature, and desorption conditions. The maximum adsorption capacities of AMP and CLI on GO nanosheets were found to be 33.33 mg g-1 and 47 mg g-1, respectively. The adsorption isotherm data can be well fitted by Temkin (AMP and CLI) and Freundlich (AMP), and the kinetics of adsorption followed the pseudo-second-order rate equation. The thermodynamic parameters were calculated, indicating that the adsorption process of both analytes were spontaneous and exothermic. In addition, the d-SPE following HPLC analyses showed good linearity in the range of 0.5-200 ng mL-1 (R2= 0.999) for AMP and 1-200 ng mL-1 (R2= 0.999) for CLI, with LOD of 0.04 and 0.24 ng mL-1 for AMP and CLI, respectively. The percent of extraction recoveries and intra and inter-day precisions (expressed as RSD %, n=3) were in the range of 96.4-101.6%, 2.2-3.0 and 3.7-4.7 for AMP and 94.2-98.6%, 2.2-3.8 and 3.5-4.6 for CLI, respectively. The preconcentration factor of 20 was achieved for both analytes. According to these results, it can be concluded that the validated technique is a simple, cost-effective and repeatable for analysis of AMP and CLI in water samples.