Polymyxin B component or salt thereof, and preparation and application thereof

A method for preparing a salt of a polymyxin B component, a molecular formula of the polymyxin B component being C56H96N16O13, the method comprising:

• isolating the polymyxin B component from polymyxin B or a salt thereof by preparative liquid chromatography;
• and
• subjecting the polymyxin B component to salt formation with an acid to produce the salt of the polymyxin B component;
• wherein a chromatographic column used in the preparative liquid chromatography is a C18 column;
• a mobile phase used in the preparative liquid chromatography is a mixture of an aqueous formic acid solution and acetonitrile, where a volume percentage of formic acid in the aqueous formic acid solution is greater than 0 and less than or equal to 10%;
• a volume ratio of the aqueous formic acid solution to acetonitrile is (99-1):1;
• a flow rate of the mobile phase is 5-20 mL/min;
• an injection volume is 50-1000 μL;
• and a detection wavelength is 190-400 nm;
• individual fractions separated by the preparative liquid chromatography are detected by the ESI-MS and the polymyxin B component of interest is collected;
• and
• the ESI-MS is performed in a positive ion mode with a scanning range (m/z) of 50-3200.