Solid phase extraction using a semi-covalent imprinted poly(3-isopropenyl-α,α-dimethylbenzylamine) coupled to batch injection analysis with amperometric detection for tetracyclines determination in milk samples at ultratrace levels

A novel electroanalytical method for tetracyclines (TC) determination in milk samples at ultratrace levels by integrating molecularly imprinted solid-phase extraction (MISPE) with a batch injection analysis (BIA) system using an AuNPs-modified screen-printed carbon electrode is described. In the MISPE procedure, 50.0 mL of sample was preconcentrated using 100.0 mg of the imprinted polymer at pH 5.0, and the analytes were subsequently eluted with 3.0 mL of MeOH containing 0.5% HAc. Preconcentrated TC was injected into the BIA system, and amperometric measurements at AuNPs-modified screen-printed carbon electrode were recorded at 1.2 V vs Ag/AgCl. Linear response in the concentration range of 11 to 300 nmol L⁻¹ (R² = 0.993) was obtained, with limits of detection and quantification of 3 and 11 nmol L⁻¹, respectively. For concentrations of 30 and 100 nmol L⁻¹, intra-day (n = 6) and inter-day (n = 2) precision showed RSD (relative standard deviation) values of 1.71–3.78% and 2.81–4.38%, respectively. Tetracycline and structurally related compounds (oxytetracycline and chlorotetracycline) were determined in milk samples, and the accuracy of the method was confirmed by satisfactory recovery values (93–102%) when compared with High-Performance Liquid Chromatography-Diode Array Detector (HPLC-DAD) results. • A semi-covalent imprinted polymer was successfully applied for TCs preconcentration in milk samples. • The MISPE method associated with BIA-AD, furnished lower LOD and LOQ, 3 nmol L -1 and 11 nmol L -1 , respectively. • The samples were analyzed without matrix interferences using aqueous calibration solutions (external calibration). • No washing step was needed, and high sample throughput was observed.