Optimization of residual tetracycline analysis in soils and manure using SPE-HPLC and pilot survey in Tianjin

Tetracyclines(TCs) are the most commonly detected antibiotics reminded in soils and manures in China. The survey of the residual status of tetracyclines is important for evaluating possible biological risks caused by direct exposure of bioorganisms and human beings. In this study, Analytical methods of three kinds of tetraclyinces, oxytetracycline, tetracycline and chlortetracycline, is optimized using SPE-HPLC. The residual status of TCs in soils and manure in Tianjin was investigated using the optimized method. The obtained method recovery rates for soils and manure are increased to the range of 52%-95%. In the surveyed feces samples from intensive piggeries and poultries, CTC is detected in 78% of manures with the highest mg/kg, and OTC and TC are detected in 56% of feces with the highest values of 34.8 and 22.7mg/kg, respectively. TCs are also detected in the market manure in Tianjin with similar residual levels and percentages to those in the feces samples. The total percentage of garden soils containing detectable TCs is 64% of the surveyed soils, and those for OTC, TC and CTC are 18%, 36% and 32%, respectively. The highest values for OTC, TC and CTC are 105.6, 196.7 and 477.8 g/kg in dry weight respectively. The residual levels in soils under facilities are higher than those in open fields. In 25% of surveyed garden soils, the total amounts of three kinds of TCs are higher than those in the trigger lines causing biological safety.