Development of optical detection for antibiotic residues: oxytetracycline in freshwater aquaculture

Abstract

This study satisfies the primary need for a simple monitoring scheme for antibiotic residue content in freshwater systems to regulate and prevent immunization of aquaculture species to antibiotics. A series of antibiotic solutions with decreasing concentrations (from 5ppm to 1ppm) were prepared, with each solution containing fixed amounts of the reagents (p-Chloranilic acid in acetonitrile solution, and pure acetonitrile) and a buffer solution to distinctly simulate the environmental conditions of actual freshwater systems. Using the UV-Vis Spectrophotometer with the optimum wavelength of 519nm, the stability, repeatability, and sensitivity tests were performed, where relative standard deviation (RSD) values of less than 10% were obtained. The limit of detection was also calculated to be 0.54ppm, using the RSD result from the sensitivity test. Actual freshwater sample was gathered and subjected to a repeatability test using the same working wavelength. Results showed that the trend in the absorbance reading for the real water sample differed with the laboratory standard samples. This shift may have been caused by other interfering chemicals used in aquaculture that were present in the sample. Modified detection method of Oxytetracycline (OTC) in freshwater was made to provide solution to the main objective.