A high-performance liquid chromatographic method for quantitating bupropion in human plasma or serum.

We report a high-performance liquid chromatographic (HPLC) procedure for quantitating bupropion in serum or plasma for the purpose of therapeutic monitoring. Bupropion and its internal standard, a fluorinated analogue of bupropion, are extracted into hexane-isoamyl alcohol (96:4) after the addition of 400 microL 0.1N KOH. The organic phase is evaporated, reconstituted with 200 microL acetonitrile, and then analyzed on a silica column using a mobile phase consisting of 95% methanol and 5% NH4H2PO4. The ultraviolet detector is set to monitor 248 nm. Within-run and total precision at a therapeutic concentration of 30 ng/mL are 5.2 and 8.5%, respectively. The lower limit of quantitation is 5 ng/mL, and the upper limit of linearity is 400 ng/mL. More than two dozen drugs and metabolites were tested for interference; fluoxetine was the only analyte demonstrating a retention time that would interfere with bupropion quantitation. Chromatographic analysis time per injection is less than 7 min. This procedure combines a single-step extraction with HPLC analysis to provide rapid and reliable analysis of bupropion.