RESUMO
Iron-tannic nanoparticles were used as a new adsorbent for dispersive solid phase extraction (DSPE) synergized with cloud point extraction (CPE) to enrich four tetracyclines (oxytetracycline, tetracycline, chlortetracycline, and doxycycline) prior to high-performance liquid chromatographic determination. DSPE and CPE were performed simultaneously in a one-pot co-extraction to form iron-tannic nanoparticles in-situ and pre-concentrate the tetracyclines. The parameters affecting the extraction efficiency were investigated. Using the optimal parameters, linear calibrations ranging from 2.63 to 1000 ng mL-1 were obtained, with determination coefficients greater than 0.996. The limit of detection was found to be 1.06-3.19 ng mL-1, while the limit of quantification was 2.63-10.65 ng mL-1. Precision was expressed as a relative standard deviation of less than 10%. The residues of the four tetracyclines in milk, eggs, honey, chicken liver, and chicken kidney samples were determined by the proposed method. The recoveries ranged from 79.3 to 107.1%. The results indicated that the proposed method was an alternative method for the extraction and pre-concentration of tetracyclines with high extraction and enrichment efficiency. In addition, it promoted rapidity and environmental friendliness.