we use this method analyzing biodiesel. We use std 1-5 (From SUPELCO)for calibration. i am confused each time i input the concentration level into the calibration table. For example, std 5 contains 50ppm glycerin, which is 0.005%. However, i need input 0.05%. I don't know why. I am sure 0.05% is right since the max concentration of free glycerin in biodiesel should be 0.02%. std 5 is the highest level and should be higher than 0.02%. Any thougts will be highly appreciated.