Molecularly Imprinted Solid-Phase Extraction of Tetracyclines Residue from Milk Using Internal-Surface Reversed-Phase Hybrid Composite Packing Materials

A novel internal-surface reversed-phase-molecularly imprinted polymer based on hybrid composite was developed for solid-phase extraction (SPE) of tetracyclines antibiotics from milk. The condition of loading, washing and eluting solvents in solid-phase extraction were investigated and evaluated by the recovery and retention of tetracyclines to obtain the optimum solid-phase extraction conditions. Under the optimal solid phase extraction conditions, three tetracyclines residues in milk were separated and detected by SPE-HPLC with better clean-up and enrichment. The mean recoveries of tetracycline antibiotics in milk were 85-106 % for tetracycline, 76-88 % for chlortetracycline and 90-94 % for doxycycline respectively, with relative standard deviations (RSDs) of 3.3-5.8%. The limits of detection (LOD, S/N = 3) and the limits of quantitation (LOQ, S/N = 10) of the proposed method were 10.4 and 34.7 mg kg(-1) for tetracycline, 13.8 and 46 mg kg(-1) for chlortetracycline and 7.5 and 25.1 mg kg(-1) for doxycycline, respectively.