Direct analysis of the dopamine agonist (-)-2-(N-propyl-N-2-thienylethylamino)-5-hydroxytetralin hydrochloride in plasma by high-performance liquid chromatography using two-dimensional column switching.
A reversed-phase, two-dimensional, liquid chromatographic method incorporating column switching and electrochemical detection was used for the direct analysis of the dopamine (D2) agonist (-)-2-(N-propyl-N-2-thienylethylamino)-5-hydroxytetralin hydrochloride in plasma. Sample work-up consisted of addition of internal standard, filtration, then direct injection of the plasma sample onto an internal surface reversed-phase (ISRP) guard column where the dopamine agonist and internal standard were separated from plasma proteins. An automated pneumatic valve was then used to switch to a stronger eluent which stripped the retained substances from the ISRP support onto a C18 analytical column where the analytes were separated from endogenous biological interferences. A dual-electrode electrochemical detector was used to minimize interferences and provide the desired sensitivity. The method has a detection limit of 1.5 ng/ml and requires a total assay time of 20 min per plasma sample. The method is linear from 1.5 to 1000 ng/ml and yielded greater than 80% drug recovery for plasma concentrations greater than 10 ng/ml. Precision for the method at 100 ng/ml yielded a relative standard deviation of 4.4%. Reproducibility was within 6.5% on a 20 ng/ml spiked plasma sample assayed on different days by different people. The method has successfully been applied to human plasma samples and for pharmacokinetic studies in rats and monkeys.
Whitby Research, Inc., Irvine, CA 92715.
S C
SC
Ruckmick
B D
BD
Hench
D000818:Animals; D002417:Cattle; D002851:Chromatography, High Pressure Liquid / Q000295:instrumentation / Q000379:methods*; D015259:Dopamine Agents / Q000032:analysis*; D010949:Plasma / Q000737:chemistry*; D013764:Tetrahydronaphthalenes / Q000032:analysis*; D013876:Thiophenes / Q000032:analysis*
D015259:Dopamine Agents; D013764:Tetrahydronaphthalenes; D013876:Thiophenes; C047508:rotigotine