Determination of the adenosine A(1) agonist N-6-cyclopentyladenosine in rat blood by solid-phase extraction and HPLC

A solid-phase extraction procedure has been developed for the isolation of the adenosine Al receptor agonist N-6-cyclopentyladenosine from rat blood. The biological samples were spiked with N-6-cyclopentyladenosine and the an alogue N-6-cyclohexladenosine (internal standard), diluted with sodium hydr oxide, loaded onto disposable cartridges with subsequent desorption with me thanol and analysis by HPLC. The performance of columns pre-packed with dif ferent C18-bonded silica phases ol with a polymeric reversed-phase sorbent (Oasis HLB) was assessed. The highest extraction efficiencies (recovery rat es > 83.3%) for the two Nb-alkyl substituted adenosines were achieved by th e Oasis HLB cartridges. In addition, the polymeric sorbent provided reprodu cible recoveries (relative standard deviation < 4.8%), whereas large variat ions (relative standard deviation values, 9-16.3%) in the extraction yields were observed using the conventional silica-based C18 cartridges. The desc ribed sample preparation method is rapid, simple, selective and it is suita ble for pharmacokinetic studies. (C) 2001 Elsevier Science B.V. All rights reserved.