Ultrasonic or accelerated solvent extraction followed by U-HPLC-high mass accuracy MS for screening of pharmaceuticals and fungicides in soil and plant samples

Different veterinary pharmaceuticals are used in agricultural livestock becoming a source of environment contamination. Furthermore, no regulation exists for the concentration limits of pharmaceuticals in soil or water. Monitoring programs for environment contamination with pharmaceuticals are needed, requiring new sensitive and selective screening methods. The present study focuses on developing a method for the simultaneous scanning of forty-two compounds (pharmaceuticals, azole biocides and fungicides) in soil and plant material samples. For extraction purposes the use of ultrasonic assisted and accelerated solvent extraction (ASE) were compared. The extract was purified and concentrated by applying a solid phase extraction step followed by ultra-high-performance-chromatographic separation and accurate-mass spectrometric detection using Exacte Orbitrap technology (FWHM 50,000). The effects of the different extraction solvents and conditions on the extraction efficiency were tested. Although both extraction approaches are applicable the optimal extraction efficiency was obtained by applying accelerated solvent extraction using solvent mixtures containing acetone for soil and methanol for plant samples. An ASE process has been validated for the determination of selected pharmaceuticals and fungicides in soil and in plant material. The recoveries from soil samples were >70% for more than 68% of the compounds. The levels of detection were ≤10 μg kg−1 for 93% of the compounds tested. The recoveries from plant material were >70% for 64% of the compounds tested. The levels of detection were ≤10 μg kg−1 for 66% of the compounds. The developed method was used to screen soil and plant material collected throughout the Netherlands and oxytetracycline residues were detected.