PHOSPHORIMETRIC DETERMINATION OF DIPYRIDAMOLE IN PHARMACEUTICAL PREPARATIONS

Room temperature phosphorescence was applied to the determination of d ipyridamole in pharmaceutical preparations. The response was linear in the concentration range 100-1600 ng ml(-1). The use of phosphorescenc e enhancers such as thallium(I) nitrate (external heavy atom), sodium dodecyl sulfate (microemulsion stabilizer) and sodium sulfite (deoxyge nation agent) was studied and optimized to obtain maximum sensitivity and adequate selectivity. The determination was performed in 0.026 M s odium dodecyl sulfate, 0.0156 M thallium nitrate and 0.02 M sodium sul fite. The pH value was 11.5, adjusted by adding sodium hydroxide. The phosphorescence was totally developed in 15 min, after that the intens ity was measured at lambda(ex) = 303 nm and lambda(em) = 616 nm. The r ecovery of the method was tested on commercial formulations containing dipyridamole. The recoveries obtained were 94.67 +/- 0.58% for Persan tin and 96.75 +/- 1.37% for Asasantin. The overall least squares regre ssion method was applied to find the most exact straight line that fit s the experimental data. The detection limit according to the error pr opagation theory was 16.4 ng ml(-1). The repeatability and relative st andard deviation were also determined according to this theory.