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Electrophoretic total analysis of trace tetracycline antibiotics in a microchip with amperometry

The preconcentration, separation, and electrochemical detection of a series of tetracycline (TC) antibiotics in a microfluidic channel were preformed. The electrophoretic experimental parameters to analyze TC, oxytetracycline, chlortetracycline, and doxycycline antibiotics were investigated with a cellulose‐dsDNA‐modified carbon paste electrode. Modification of the electrode improved detection performance by enhancing the signal‐to‐noise characteristics without surface fouling of the electrode. Field‐amplified sample stacking and field‐amplified sample injection techniques were employed for on‐chip preconcentration of the TC series. The sensitivity of the method was improved 10 900‐fold when compared with conventional MEKC‐electrochemical detection analysis. The overall recoveries for TC, oxytetracycline, chlortetracycline, and doxycycline were 87, 89, 87, and 81%, respectively, with 6.0% RSD. The limits of detection for the series were estimated between 1.5 and 4.3 nM. Applicability of the method to beef samples was successfully demonstrated.