Flow-injection chemiluminescence detection for studying protein binding of terbutaline sulfate with on-line...

The binding of terbutaline sulfate to bovine serum albumin was studied in vitro using the technique of microdialysis sampling combined with flow-injection chemiluminescence analysis (FIA-CL). In the presence of formaldehyde, terbutaline sulfate can be oxidized by KMnO(4) to produce high chemiluminescence emission in sulfate acid media. The concentration of terbutaline sulfate is proportional with the CL intensity in the range of 1 x 10(-7)-2 x 10(-5) mol l(-1) with a detection limit of 3 x 10(-8) mol l(-1). The drug and protein were mixed in different molar ratios in 0.067 mol l(-1) phosphate buffer, pH 7.4, and incubated at 37 degrees C in a water bath. The microdialysis probe was utilized to sample the mixed solution at a perfusion rate of 5 microl min(-1) and the dialytic efficiency of terbutaline sulfate under the experimental conditions was 26.3%. The data obtained by proposed microdialysis flow-injection chemiluminescence method was analyzed with Scrathard analysis and Klotz plot. The estimated association constant (K) and the number of the binding site (n) on one molecule of BSA by Scrathard analysis were 4.11 x 10(4) l mol(-1) and 1.06, respectively. The proposed system proved that FIA-CL coupled with on-line microdialysis sampling is a simple and reliable technique for the study of drug-protein interaction.