Ion-paired solid phase extraction as a sample preparation strategy for the high-performance liquid chromatographic determination of oxytetracycline in the bryophyte Fontinalis antipyretica Original Research Article

Oxytetracycline (OTC) is one of the major antibacterial agent used in freshwater fish farming. Because of its rapid decomposition rate in sediments, it is difficult to monitor OTC in the freshwater environment. Fontinalis antipyretica is known for its bioaccumulation properties. Determining OTC concentration in F. antipyretica by HPLC was a real challenge because pigments coextracted with OTC. Ion-pairing was used in the clean-up procedure to improve the selectivity of the C18 solid phase extraction. Octanesulfonic acid was used as counter-ion. Tetracycline was used as internal standard. The linearity ranged between 100 and 1000 ng/g and limits of detection and quantitation were 30 and 100 ng/g, respectively. Mean recovery for OTC was 48.2% and the validation procedure demonstrated that the method was selective, reliable and precise enough to allow environmental monitoring. This method was applied to a 25 days experimental study showing the bioaccumulation of OTC by the bryophyte F. antipyretica.