The Mobility And Transformation Of Cyadox And Its Main Metabolites In Soil

Quinoxalines are broad-spectrum antibiotics with growth-promoting activity, and have been extensively used in food animals since 1970s. Carbadox and olaquindox are the early members which have been strictly limited or banned to be used in food animals because of their toxicity to human and animals. Cyadox (CYX) is a new candidate of quinoxalines. Some studies show that cyadox can promote the growth and improve the feed conversion in broilers, swine, sheep and fish with lower toxicity and higher safety. So cyadox will be an excellent replacer of the old quinoxalines. But there have not been any report concerning the toxicity of cyadox to the environment and the fate in the environment. In this study, the methods have been developed for the HPLC detection of cyadox and its main metabolites (desoxycyadox(DEO) and quinoxaline-2-carboxylic acid(QCA)) in sandy loam and clay loam, and then reviewed the sorption and biodegradation ability of the three drugs in the soil. This study will provide some guidance for the dealing with the excreta of the hoggery and the hennery.The adsorption and desorption experiments are very important to evaluate the binding ability of the compounds to the soil and this experiment assessed the adsorption ability of cyadox and its main metabolites in the sandy loam and clay loam in room temperature. 0.01mol/L CaCl₂ solution was used as the environmental water. The experiment indicated that CYX and DEO were relativelyeasily adsorbed to the soil. But meanwhile CYX was easily desorbed from soil. Cyadox and desoxycyadox could reach the sorption balance in short time (8h). With the concentration 2～10mg/L, the adsorption coefficient(Kads)of was 19.1～13.6 L/kg for CYX and 226.1～5.1 L/kg for DEO. QCA could reach equilibrium in 24h and the Kd were all below 1L/kg with the concentration 0.25～5mg/L. The characters of the soil could not influence the adsorption ability of the compounds. The experiment showed that CYX and QCA had strong flowability in the environment and might be harmful to the water environment.