A rapid, sensitive and selective liquid chromatography/atmospheric pressure chemical ionization tandem mass spectrometry method for determination of fenretinide (4-HPR) in plasma

A simple and sensitive liquid chromatography/tandem mass spectrometry (LC–MS/MS) method using an atmospheric pressure chemical ionization source (APCI) for the quantification of fenretinide (4-HPR) in mouse plasma was developed and validated. After a simple protein precipitation of plasma sample by acetonitrile, 4-HPR was analyzed by LC–APCI–MS/MS. High-performance liquid chromatography (HPLC) separation was conducted on a Hypurity C18 column (50 mm × 2.1 mm, 5 μm) with a flow rate 0.60 mL/min using a gradient mobile phase comprised of 0.05% formic acid in water (A) and methanol (B), and a run time of 4.5 min. The elimination of a tedious sample preparation process and a shorter run time substantially reduced total analysis time. The method was linear over the range 0.5–100 ng/mL, with r > 0.998. The intra- and inter-assay precisions were 1.4–9.2% and 5.1–8.2%, respectively, and the intra- and inter-assay accuracies were 93.9–98.6% and 92.7–95.3%, respectively. The absolute recoveries were 90.3% (1.5 ng/mL), 97.0% (7.5 ng/mL) and 92.1% (75.0 ng/mL) for 4-HPR, and 99.1% for the internal standard (150 ng/mL). The analytical method had excellent sensitivity using a small sample volume (30 μL) with the lower limit of quantification (LLOQ) 0.5 ng/mL. This method is robust and has been successfully employed in a pharmacokinetic study of 4-HPR in a mouse xenograft model of neuroblastoma.