Saliva, urine and plasma analysis of dyphylline via HPLC

Improved assay methods for determination of dyphylline levels in plasma, saliva, and urine utilizing high pressure liquid chromatography have been developed. Detection of levels as low as 25 ng/ml from 0.5 ml plasma and 50 ng/ml from 0.5 ml saliva were possible. Both procedures utilized the same extraction process. A separate extraction process was used for dyphylline analysis in urine due to the presence of interferring substances occurring with previous methods. The method was applied to samples of one subjects plasma, saliva and urine after administration of dyphylline.