High performance liquid chromatography with pulsed amperometric detection for the determination of tetracycline antibiotics in shrimps

Abstract

The oxidation of tetracyclines; i.e. tetracycline, oxytetracycline, chlortetracycline and doxycycline was investigated at Au and anodized BDD electrodes using cyclic voltammetry. It was found that tetracyclines provided well-defined cyclic voltammogram at both electrodes. The PAD waveform parameters were optimized at both Au and anodized BDD electrodes by HPLC system. The HPLC conditions were carried out using the mobile phase of phosphate buffer (0.01M, pH 2.5) - acetonitrile (80:20; v/v) on a C₁₈ column at a flow rate of 1.0 mL/min at room temperature. The analytical performance of the Au and anodized BDD electrodes was examined by HPLC-PAD. It was found that the anodized BDD electrode provided lower detection limit, wider linear range and higher sensitivity than the Au electrode. The optimal PAD waveform parameters at the anodized BDD were 1.5 V detection potential (E[subscript der]) for 290 ms (200 ms delay time and 90 ms integration time), 2.0 V oxidation potential (Eoxd ) for 200 ms oxidation time (t[subscript oxd]) and 0.4 V reduction potential (E[subscript red]) for 200 ms reduction time (t[subscript red]). HPLC-PAD with the anodized BDD electrode has been successfully applied to determine tetracycline antibiotics in shrimps. The linear concentration range of tetracyclines was 0.1 to 100 ppm with the detection limit of 0.01-0.05 ppm. The recovery was in the range of 75.0 - 98.4% with RSD < 10%. The proposed method was applied to analyse tetracyclines in shrimp samples. The results from proposed method gave higher % recovery than those obtained by AOAC official method.