Dispersive liquid‐liquid microextraction followed by magnetic nanoparticles retrieval of extract for separation and preconcentration of tetracycline from real samples before its selective spectrophotometric determination based on azo dye formation

Abstract

AbstractA sensitive and selective method is reported for the determination of the low amount of tetracycline in real samples. The tetracycline is extracted and preconcentrated by dispersive liquid‐liquid microextraction followed by retrieval of the extract with magnetic solid‐phase extraction. The extracted analyte is determined by a selective spectrophotometric method based on the formation of a water‐soluble violet mono azo dye between the tetracycline and diazotized p‐nitroaniline in the basic medium. The dispersive liquid‐liquid microextraction was performed using acetonitrile as the disperser solvent and 1‐octanol as the extracting solvent. The extracted tetracycline in the dispersive liquid‐liquid microextraction step was retrieved by dispersed hydrophobic oleic‐acid‐modified Fe3O4 magnetic nanoparticles. Thus, the method enjoyed the high surface area and strong magnetism properties of these nanoparticles avoiding the time‐consuming centrifugation or column‐passing processes. Finally, the tetracycline was eluted from the magnetic solid phase into 0.5 ml of ethanol, and coupled with diazotized p‐nitroaniline in the basic medium for spectrophotometric quantification. Under the optimum conditions, good linearity (in the range of 7.6–650.0 μg/L with R2 = 0.9987), low detection limit (2.3 μg/L), and preconcentration factor of 30.0 were obtained. The proposed method was successively applied to the determination of tetracycline in different samples.