Magnetic-assisted dispersive solid phase extraction technique for determination of tetracycline in urine samples followed by spectrophotometric detection using chemometrics methodology

Tetracyclines (TCs) represent a class of antibacterial compounds [1].They are broad-spectrum antibiotic agents extensively used to control bacterial infections in humans and animals [2]. However, the widespread use of them could lead to TC residues in animal-producing food [3]. In this paper an exact and sensitive solid phase extraction (SPE) method based on magnetic nano-composite was developed for the determination of tetracycline antibiotic in urine using ultra-violet (UV) spectrophotometric detection. In this way, Chitosan-coated Fe3O4 particles were prepared as a magnetic adsorbent by reverse oil-in-water micro-emulsion system [4] using glutaraldehyde as the emulsifier. Coating chitosan onto the magnetic particles was confirmed by transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectra and magnetic measurements. Several important parameters affecting the extraction efficiency have been investigated and optimized for the proposed method using response surface methodology. Chitosan-coated Fe3O4 adsorbent was shown to be effective for tetracycline extraction with a maximum adsorption capacity of 4.87 mg g-1 within 30 min by adding 50 μg adsorbents into 10 mL aqueous solution of tetracycline with the concentration of 100 μg L-1. In addition, the recovery rate of Chitosan-coated Fe3O4 particlesand recovery rate of chitosan-coated Fe3O4 adsorbent reached to 99.95% for 40 min, showed its excellent recoverable performance. The developed methods were compared in the terms of validation parameters including linearity, sensitivity, precision and accuracy. The linearity range for UV detection was within 4 μg L−1 to 0.8 mg L−1 with method limit of detection as low as 0.7 μg L−1 for tetracycline with the correlation coefficients demonstrating good linearity (0.985-0.991). Accuracy was expressed as recovery with values ranging from 97.04 to 103.16% for UV detection. Excellent method reproducibility was found by intra- and inter-day precisions, yielding the RSDs less than 3.28% and 3.91%, respectively.