Uptake of oxytetracycline, sulfamethoxazole and ketoconazole from fertilised soils by plants

Abstract

This study was performed to investigate the potential for a set of two antibiotics and one antifungal compound to be taken up from the soil by plants. Plants are used for animal or human consumption, and so the measured concentrations in the plant material will be used to model potential human exposure to these compounds. The uptake by two types of plants (grass and watercress) from two types of soil was studied. The compounds used for these experiments were sulfamethoxazole, oxytetracycline and ketoconazole at concentrations of 5 and 10 mg kg⁻¹ in the soil. The compounds of interest were extracted out of the plant matrix by applying accelerated solvent extraction. Analyses were carried out by a LC–MS/MS. From the results, it was concluded that the plant materials used for this study were able to take up sulfamethoxazole and ketoconazole when the soil was contaminated with these compounds at a concentration ranging from 5 to 10 mg kg⁻¹. Sulfamethoxazole was detected in all samples, at levels ranging from 7 to 21 µ kg⁻¹ for grass and 4 to 7.5 µ kg⁻¹ for watercress. For ketoconazole, the results showed low absorption. Oxytetracycline was not detected in any sample. A partition-limited model approach was applied for the comparison of experimental and estimated data, and the relationship between physicochemical properties of the compounds and plant uptake was highlighted.

Keywords:

• plant uptake
• antibiotics
• antifungal
• partition model
• passive transport