Lab-on-valve system integrating a chemiluminescent entity and in situ generation of nascent bromine as oxidant for chemiluminescent determination of tetracycline.

A novel configuration of a lab-on-valve (LOV) system was fabricated and applied for chemiluminescence (CL) detection by integrating a demountable Z-type flow cell onto the LOV unit. A bismuthate immobilized microcolumn was incorporated in one port of the LOV for in situ oxidation of KBr and generation of bromine as oxidant for the bromine-hydrogen peroxide-tetracycline (TC) chemiluminescent reaction. The nascent bromine reacts with hydrogen peroxide and produces a weak CL signal, the intensity of which was significantly enhanced in the presence of TC following an energy-transfer mechanism. A novel procedure for tetracycline quantification was therefore developed based on the present system. When compared with the reported flow injection-CL methods for TC, this procedure not only provided an improved detection limit of 2.0 microg L(-)(1) but also minimized sample and reagent consumption. A linear range of 6.0-10 000 microg L(-)(1) was derived along with RSD values of 5.9 (at the concentration level of quantification limit) and 2.2% (at 50 microg L(-)(1)), and a sampling frequency of 120 h(-)(1) was achieved. The system was validated with a National Standard Procedure (GB/T 18932.4-2002, HPLC with UV detection) by measuring TC contents in commercial milk samples.