Abstract
Potassium dehydroandrographolide succinate (DASโK) has antibacterial and antiviral effects. It has been used widely for the treatment of virus pneumonia, malaria and respiratory infections. In this work, a novel flowโinjection chemiluminescence (CL) method for the determination of DASโK was proposed. The method is based on the reaction between DASโK and hexacyanoferrate(III) in alkaline solution to give weak CL signal, which is enhanced by rhodamine B. The experimental conditions for the CL reaction were optimized and the possible reaction mechanism was discussed. Under the optimum conditions, the concentration of DASโK is proportional to the CL intensity in the range of 0.1โ80 ฮผmolยทL^โ1^ with a detection limit of 0.05 ฮผmolยทL^โ1^. The interaction of the DASโK with bovine serum albumin by onโline ultrafiltration and flowโinjection chemiluminescence was studied. The concentrations of unbound DASโK from ultra filter tube were determined by the flowโinjection CL method. The binding parameters were estimated by the Scatchard plot and Klotz plot. The proposed system proved that FIAโCL coupled with onโline ultrafiltration sampling was a fast and simple technique for the study of drugโprotein interaction.