External Standard Calibration Notes: The sample must fall within a range bracketed by the calibration solution. I suggest that you include a range which covers concentration values which are ~ 50% or more outside of the expected range. Dissolve the final calibration standards into the mobile phase (or a weaker solution) when preparing the injection vials from the stock solution. At least five different concentration values should be used per order of magnitude (large range = more stds). *Inject the same volume of solution (different concentration) for each calibration standard onto the column (Do NOT inject different volumes of solution from one std vial). Plot peak response vs concentration. Make sure you have a linear response and that the line goes through the origin (zero intercept, ideally). Once you have injected all of the standards, repeat the process again at least three more times (or use multiple injections) to determine overall reproducibility before constructing the final calibration table