Step 1: Dissolve the crude Melanotan I peptide in 100 mL of purified water and filter the mixture through a 0.45 μm membrane to obtain a crude peptide solution.
Step 2: Purify the crude Melanotan I peptide using High-Performance Liquid Chromatography (HPLC). Utilize a DAC-HB50 dynamic axial compression column with a gradient elution process, employing Mobile Phase A (0.05 wt% trifluoroacetic acid in water) and Mobile Phase B (0.05 wt% trifluoroacetic acid in acetonitrile). Monitor the sample using a UV detector and collect the peptide solution corresponding to the target peak in fractions.
Step 3: Following HPLC purification, obtain 180 mL of Melanotan I trifluoroacetate solution with a purity exceeding 99%; concentrate this via rotary evaporation to yield 50 mL of solution.
Step 4: Equilibrate the chromatography column with deionized water and load the sample (50 mL of the Melanotan I trifluoroacetate solution with >99% purity). Elute for 50 minutes using a 2% aqueous acetic acid system. Concentrate the collected target product to 80 mL via rotary evaporation, then subject it to pre-lyophilization and lyophilization processes. Finally, obtain 5.33 g of high-purity Melanotan I peptide, representing a yield of 32.33%.