I wonder if instead of making solutions of different concentrations and injecting same volume from each solution in order to build a calibration curve, one can use a solution of one concentration and program auto sampler of the validated HPLC instrument to inject various volumes? I tried, and didn't find any difference in results. I believe, that old technique has been used to compensate for the variations in the injected volumes when manual injectors were in use. Does anyone use "new" technique, which is faster and supposed to be more accurate or does anyone know of any specific requirements?