Determination of trace tetracyclines in surface water by aluminum hydroxide coprecipitation coupled with high-performance liquid chromatography

A simple method for the determination of trace tetracyclines (TCs) in surface water samples by aluminum hydroxide coprecipitation coupled with high-performance liquid chromatography (HPLC) with UV detection was developed. Tetracyclines (oxytetracycline hydrochloride, tetracycline hydrochloride and chlortetracycline) were coprecipitated by aluminum hydroxide precipitate at pH 6.0. The obtained precipitate by centrifugation was dissolved with 1 mol L−1 HCl, and the pH of the solution was adjusted to 4.0 for HPLC analysis. The solution pH value, adsorption time for coprecipitation, centrifugation rate and time were optimized. Under the optimum conditions, calibration curves of the tetracyclines were in the range of 5–50 ng mL−1, with a relative coefficient (R2) of 0.9960 and a limit of detection (LOD) of 0.115 ng L−1 for chlortetracycline (CTC), of 0.9990 and 0.0935 ng L−1 for oxytetracycline (OTC), and 0.9990 and 0.0817 ng L−1 for tetracycline (TC). The proposed method was applied to river water and lake water samples, and the recoveries were in the range of 81.70% to 96.45%, at three spiked concentration levels of 15 ng mL−1, 30 ng mL−1 and 40 ng mL−1.