LC Analysis of Oxytetracycline and Chlortetracycline: Application for In Vitro Bio-Equivalence Study of Veterinary Medicines

Nitrogen-doped carbon dots derived from hawthorn for the rapid determination of chlortetracycline in pork samples

In recent years, the methods for rapidly detecting antibiotics using the unique fluorescent properties of carbon dots have attracted increasing attentions. The purpose of this study is to prepare carbon dots by hawthorn and establish a rapid fluorescence sensor for the detection of chlortetracycline in pork samples. An environmentally friendly nitrogen-doped carbon dots (N-CDs) with hawthorn powder as the carbon source and diethylenetriamine (DETA) as the nitrogen source was synthesized by one-pot hydrothermal process. The preparation conditions of the N-CDs were optimized. Subsequently, the characteristics of the N-CDs were elucidated by fluorescence, UV absorption, transmission electron microscope, fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The N-CDs showed a quantum yield of 22.96%, emission at 447 nm at the maximum excitation wavelength of 370 nm and an average particle diameter of 3.17 nm. Meanwhile, the factors affecting the fluorescence intensity of the N-CDs were studied. Moreover, the fluorescence quenching method for detecting chlortetracycline in pork was established and optimized. Under the best experimental conditions, the linear range (R² = 0.9992) was developed over 0.4-20 μg mL^-1 with a detection limit of 0.073 ± 0.005 μg mL^-1 (S/N = 3). Chlortetracycline in pork samples had been successfully detected with good recoveries of 93.62%-103.18%, which suggested that the study provided a new approach for the detection of chlortetracycline in pork.