DETERMINATION OF SUB-MICROGRAM QUANTITIES OF CLONIDINE IN BIOLOGICAL-FLUIDS

A sensitive and specific GLC method using electron‐capture detection was developed for clonidine in plasma and urine. Di‐perfluoroacyl derivatives of both clonidine and the 4‐methyl analog of clonidine (used as an internal standard) were formed, and an extraction process was developed for the removal of excess derivatization reagent and endogenous biological compounds; the assay permitted quantification of 25 pg of clonidine/ml in a 4‐ml plasma sample. The assay was used to elucidate the time course of plasma concentrations in a normotensive subject following oral administration of 50, 100, and 200 μg of clonidine hydrochloride and also to determine unchanged drug excreted in the urine. Copyright © 1979 Wiley‐Liss, Inc., A Wiley Company