A high performance liquid chromatography with evaporative light scattering detector was developed for the determination of main components in polymyxin B and polymyxin E crude drugs.Analytes were separated on a Phenomenex Kinetex Biphenyl column(50 mm×4.6 mm id

5 μm) by gradient elution with methanol and 20 mmol/L ammonium acetate aqueous solution containing 0.6% formic acid as mobile phases at a flow rate of 0.5 mL/min.The parameters for evaporative light scattering detector were as follows:drift tube temperature:55 ℃

carrier gas pressure:20 psi

and the gain:250.Results showed that there were good linear relationships for the analytes in polymyxin B and polymyxin E in the concentration range of 10-200 μg/mL with their detection limits of 0.8 μg/mL and 1.2 μg/mL

and their quantitation limits of 2.6 μg/mL and 4.0 μg/mL

respectively.The intra batch recoveries for polymyxin B and polymyxin E were in the ranges of 100%-104% and 101%-103%

with intra batch relative standard deviations of 0.90%-2.4% and 0.90%-2.6%

respectively.The inter batch recoveries were in the ranges of 101%-103% and 101%-102%

with inter-batch relative standard deviations of 1.1%-1.9% and 1.3%-1.7%

respectively.Compared with microbiological detection method

the developed method is simpler

more precise and more accurate in the detection of analytes in crude drugs

and could be applied to the quality control of polymyxin B and polymyxin E crude drugs.