HPLC determination of insulin and its related substances in insulin powder for inhalation

AIM: To determine insulin and its related substances in insulin powder for inhalation by reversed phase high performance liquid chromatography method. METHODS: The initial mobile phase was solution A (0.1% trifluoroacetic acid-acetonitril 70:30) and changed to solution B (0.1% trifluoroacetic acid-acetonitril 60:40) in 30 minutes. The flow rate was 2.0 mL·min^-1, the column temperature was 30°C, the wave length was 280 nm, the injected volume was 20 μL. RESULTS: Insulin was well separated from other peaks induced in different conditions. There was good linear relationship between the amount of insulin and its peak area, the RSD was 1.1%, the insulin solution for determination was stable in 12 hours, and the quantity detected was near the added. CONCLUSION: The method is simple and accurate to detect insulin and its related substances in insulin and its preparations.