Abstract:

In this study, we developed a simple and sensitive HPLC method for the determination of lisinopril in human plasma. The sample clean-up was carried out by solid-phase extraction (SPE) using a cation-exchange (Strata-SCX^®) extraction cartridge. After a pre-column derivatization with 4-fluoro-7-nitro-2,1,3-benzoxadiazole, the reaction mixture was analyzed on an Agilent Zorbax SB^®-C₁₈ (150 mm×4.6 mm, 5 μm). The flow rate was set at 1.0 mL/min. Fluorescence detection was performed at an excitation wavelength of 470 nm and an emission wavelength of 530 nm. The mobile phase consisted of a mixture of methanol and 0.02 M sodium dihydrogen phosphate (pH = 3.0, 60:40, v/v). The average extraction recovery of lisinopril and fluvoxamine (internal standard) was >85%. The method exhibited a linear calibration curve over the concentration range of 1–1000 ng/mL with a correlation coefficient (r²) of ≥0.98 and a limit of quantification (LOQ) equal to 2 ng/mL. The within-run and between-run precisions were satisfactory with an RSD of 3.8%–13.7% (accuracy: from 95.0% to 96.4%) and 4.273%–14.3% (accuracy: from 94.4% to 98.5%), respectively.

Key words: Lisinopril, HPLC, Derivatization, 4-Fluoro-7-nitro-2,1,3,-benzoxadiazole