Automation of photochemical kinetic determinations without irradiation of the detection cell

This paper reports on the development of an open-closed configuration for continuous kinetic methods based on photochemical reactions; the configuration removes the need to use special flow cells for simultaneous irradiation and detection. The sample plug was recirculated through a circuit including the detector and a coil irradiated with an ultra-violet source. A multipeak recording per injected sample was obtained which allowed signal increments between peaks (whether successive or not) to be measured. The configuration was applied to the fluorimetric determination of thioridazine. The log-log calibration curve obtained was linear in the range over 0.1-20.0 μg/ml of the analyte. The sampling frequencies achieved were between 24 and 13 h(-1), depending on the peaks which were selected for measurement. The method was applied to the determination of the analyte in pharmaceuticals.