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Isoproterenol is a chiral catecholamine with a half-life of elimination of less than 10 min. In order to study the pharmacokinetics of this compound using microdialysis sampling, an analytical method was needed which could resolve the individual enantiomers of isoproterenol and required less than 1 microliter of sample. A capillary electrophoretic method using a run buffer containing methyl-O-beta-cyclodextrin as a chiral recognition agent was developed which could resolve the enantiomers of isoproterenol. The detection limits using UV absorbance detection were found to be too high to determine the concentration of isoproterenol in plasma for a sufficient time following administration to establish the pharmacokinetics. The detection limits were decreased three orders of magnitude to 3 ng/ml by using an amperometric detector. The detection limits were decreased to 0.6 ng/ml using an on-column concentration technique in which peak stacking was accomplished by following the sample injection with a plug of acid.

A microbore liquid chromatographic method using a phenyl stationary phase was developed for the determination of 9-amino-1,2,3,4-tetrahydroacridine (tacrine, THA) and its metabolites in microdialysis samples of bile. Analysis of microdialysis samples requires analytical methods with low detection limits and small sample volume requirements. The method uses a 1-mm I.D. phenyl column and fluorescence detection. A detection limit of 0.25 ng/ml in a 5-microliters sample was achieved for THA. This method was then used to determine THA and THA-1-ol in the bile dialysate of a rat. Because of the small sample volume requirements, a 10-min temporal resolution was achieved for the microdialysis experiment. The low detection limit allowed the THA concentration in the bile to be monitored for more than 4 h following a 1.0 mg/kg i.v. dose of THA.