Rapid determination of trace levels of tetracyclines in surface water using a continuous flow manifold coupled to a capillary electrophoresis system

A method for the determination of three tetracyclines (viz. tetracycline, oxytetracycline and doxycycline) is proposed. The method uses a flow manifold coupled on-line to a capillary electrophoresis (CE) system. The tetracyclines are preconcentrated on a STRATAX solid-phase minicolumn inserted in the manifold. This provides an average recovery of tetracyclines of 92% from spiked water samples. The proposed method allows the resolution of mixtures of tetracyclines at concentrations ranging from 7 to 45 g l^-1 and has a limit of detection of 2 g l^-1. Under optimal conditions, recoveries range from 99 to 106% and the precision is better than 7.5%. Based on the results, the method is a highly efficient choice for the separation and determination of tetracyclines in surface water samples.