High-throughput analysis of tetracycline antibiotics and their epimers in liquid hog manure using Ultra Performance Liquid Chromatography with UV detection

Antibiotics contained in animal manure can contaminate soil, groundwater and eventually surface and drinking water. To reduce the usage of antibiotics in livestock industry the EU banned their application as growth promoters in 2006. Even though the antibiotics are still used for this purpose and therefore it is necessary to control their applications.An Ultra Performance Liquid Chromatography method (UPLC) with UV detection for determination of tetracycline (TC), oxytetracycline (OTC), chlortetracycline (CTC), and doxycycline (DOX) including their epimers in the liquid hog manure was developed. The antibiotics were extracted with ethyl acetate and separated on UPLC BEH Shield RP18 column. The validated method was selective for all analytes and system suitability was assessed. Calibration curves ranged from 7.8 to 250.0 μg mL−1 with determination coefficient of 0.9999. The method limits of quantification ranged from 0.9 to 1.6 mg kg−1. Recoveries were 52.4 ± 3.8%, 72.4 ± 5.0%, 83.8 ± 5.7% and 95.9 ± 4.7% for TC, OTC, CT, and DOX, respectively. The method was used for the determination of TC, OTC, CT, and DOX in liquid hog manure samples.