Determination of Ritonavir, Saquinavir and Lopinavir in Dried Blood Spots by LC/MS/MS Comparing Different Automated Extraction Approaches

摘要

Extraction by vortexing, mixing within tips, sonicating within tips and direct elution all were demonstrated to be quantitative. Solvent conditions were demonstrated to be unique for different classes of compounds (comparing optimized conditions with prior work with neuroscience compounds), although these anti-viral compounds all behaved similarly. Matrix effect was minimal +-20percent for all analytes throughout the range on FTA Classic, Agilent and untreated paper (suppression was as much as 50percent for ritonavir and lopinavir on FTA Elute material). Extraction efficiency was measured at 69-77percent for ritonavir, 82-88percent for lopinavir and 89-100percent for saquinavir using the vortex control method. No significant presence of phospholipids detected. No statistically significant differences due to changes in hematocrit content throughout the normal population range were observed. The method is quantitative for plasma as well as blood, although with a lower recovery. Whatman FTA Classic~(~R) (DMPK B) card type afforded higher response for all three analytes. Agilent card material was easier to punch, gave better response due to smaller spot diameter, but spots tended to break apart more during traditional vortexing. Addition of internal standard in the extraction solvent generally did not track the analyte extraction as well as spotting it on the card prior to extraction. Age of control blood up to 5 weeks did not show any statistically significant differences.