A combination of β-cyclodextrin functionalized magnetic graphene oxide nanoparticles with β-cyclodextrin-based sensor for highly sensitive and selective voltammetric determination of tetracycline and doxycycline in milk samples†
Food safety problems caused by tetracycline antibiotics residues are a significant concern due to their great risk to human health even at trace levels. In the current work, a highly sensitive and selective determination of similar chemical composition tetracycline (TC) and doxycycline (DC) antibiotics in milk samples was developed by offline solid phase extraction using β-cyclodextrin functionalized magnetic graphene oxide nanoparticles (β-CD-MGONPs) followed by differential pulse voltammetric determination with a β-cyclodextrin modified carbon paste (β-CD-MCP) sensor. β-CD-MGONPs was prepared, characterized by XRD, FTIR, TEM, and TGA and applied for the removal of TC/DC using batch adsorption experiments. The effects of medium acidity, equilibration time, adsorbent dose, initial antibiotic concentration, and ionic strength were extensively investigated using UV-Vis spectrophotometry at optimal adsorption conditions. The experimental data are well described by the Langmuir isotherm and pseudo-second-order kinetic model. The maximum adsorption capacity was found to be 666.7 mg g−1 for TC and 769.2 mg g−1 for DC. Furthermore, loss in the removal efficiency was 3.5–5.6% after three adsorption–desorption cycles. Then, the electrochemical response of the β-CD-MCP sensor following β-CD-MGONPs extraction was investigated by differential pulse voltammetry (DPV) and cyclic voltammetry (CV). Under optimal electrochemical parameters, anodic differential pulse voltammetry (ADPV) at +320.0 mV and cathodic differential pulse voltammetry (CDPV) at −800.0 mV were selectively used to detect TC and DC, respectively. The response currents of the β-CD-MCP sensor exhibited a linear relationship towards TC/DC concentrations ranging from 0.5–90.0 ng L−1. The limit of detection (LOD) of TC or DC was calculated as 0.18 ng L−1. Other validation parameters confirmed the adequate applicability of the proposed system to detect TC/DC in milk samples. The proposed platform showed advantages of simplicity, rapidity, reliability, and low cost compared to other previously published reports.