Selective removal of tetracycline residue in milk samples using a molecularly imprinted polymer

In the present work, the synthesis and characterisation of a molecularly imprinted polymer (MIP) by precipitation polymerisation using tetracycline (TC) as a template molecule, methacrylic acid as a functional monomer, ethylene glycol dimethacrylate as a cross-linker, persulphate as an initiator, and methanol as a porogen solvent is described. The molecular recognition properties and selectivity of MIPs against four TCs [(TC), oxytetracycline (OT), chlortetracycline (CT), and doxycycline (DT)] were evaluated, and the results demonstrated high selectivity for four TCs in milk samples without sample treatment. Under the optimal synthesis conditions (TC/methacrylic acid/ethylene glycol dimethacrylate ratio of 1.0:7.0:50.0), the percent removal obtained was 81.83% for TC, 95.47% for OT, 96.44% for CT, and 93.25% for DT using 1.0 mL of the sample, 20 mg of the sorbent, a pH of 6.0, and 15 min of contact time. One of the tested samples was positive for the presence of OT, with a concentration of 19.83 mu g L-1, ensuring the complete removal of TC using the proposed method. The method provided significant data regarding the development of efficient and selective materials in the removal of several residues and contaminants.