Simultaneous extraction and determination of antibiotics in soils using a method based on quick, easy, cheap, effective, rugged, and safe extraction and liquid chromatography with tandem mass spectrometry

The increasing use of antibiotics has caused substantial environmental problems, which are a matter of great concern. The aim of this work was to develop a quick, easy, cheap, effective, rugged, and safe method for 20 antibiotic residues in soil. The developed method is based on extraction with acetonitrile and phosphate buffer, clean up with dispersive solid-phase extraction adsorbent using primary secondary amine, octadecylsilane, followed by liquid chromatography with tandem mass spectrometry determination. We optimized different extraction methods and the ratio of cleanup adsorbents to achieve good recoveries at seven spiking levels that ranged from 61.4 to 118.9% with a relative standard deviation below 20% (n = 5). The method quantification limit was in the range of 2-5 μg/kg for most analytes. Good linear regression coefficients greater than 0.990 were obtained. This method was applied for the analysis of real agricultural soil samples, confirming the feasibility of the method.