Determination of Melphalan by Micelle Enhanced Spectrofluorimetric Method: Application to Content Uniformity Testing and Human Plasma

This manuscript describes a responsive, rapid, validated and economical spectrofluorimetric method for determination of Melphalan in its pharmaceutical dosage forms and spiked human plasma. The proposed method is relied on the investigation of fluorescence action of Melphalan in Tween-80 micellar system. The Melphalan shows strong native fluorescence at λem 365 nm upon excitation at λex 265 nm in Tween-80 system. There was good enhancement (1.68 fold) in fluorescence intensity in the presence of Tween-80. The proposed approach has a good linearity in the concentration range of 0.2 μg/mL–2 μg/mL. The lower limit of detection and that of quantitation was 0.03 μg/mL and 0.08 μg/mL respectively. The developed method has been validated and applied for content uniformity testing of Melphalan medicines available on the market and Melphalan spiked human plasma samples. The results are statistically compared and were found to be in good agreement to those obtained by comparison methods.

Determination of melphalan in human plasma by UPLC-UV method

It is desirable to develop a fast method for quantification of melphalan due to its instability. Here we report a method for quantification of melphalan (MPL) in human plasma using a UPLC-PDA system. Briefly, 50 µL plasma sample was mixed with 25 µL internal standard (2500 ng/mL acetylmelphalan in methanol) and 25 µL 20% trichloroacetic acid, and centrifuged at 21,000 g (15,000 rpm) at 4 °C for 3 min. The supernatant (5 µL) was injected onto an Acquity™ BEH C18 LC column (2.1 × 50 mm, 1.7 µm) and eluted with 25 mM NH₄AC (pH 4.7)-acetonitrile in a gradient mode at a flow rate of 0.6 mL/min. The column kept at 40 ± 5 °C and the autosampler kept at 4 ± 5 °C. The detector set at 261 nm, and sampling rate was 40points/sec. The retention times were typically 2.11 min for melphalan and 2.38 min for the internal standard. Total run time is 4 min per sample. Calibration range was 100-40,000 ng/mL. The lower limit of quantification was 100 ng/mL. The method was validated based on the FDA guidelines, and applied to a clinical pharmacokinetic study in pediatric patients.