ABSTRACT
<p><b>AIM</b>To determine insulin and its related substances in insulin powder for inhalation by reversed phase high performance liquid chromatography method.</p><p><b>METHODS</b>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 degrees C, the wave length was 280 nm, the injected volume was 20 microL.</p><p><b>RESULTS</b>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.</p><p><b>CONCLUSION</b>The method is simple and accurate to detect insulin and its related substances in insulin and its preparations.</p>