Sample size for validation

For validation of a UV-Vis spec test method, how do you go about determining the number of measurements to take. For example, precision, should this be done over a number of days etc. Anyone any thoughts.

For any method validation like uv-visible or chromatography method PRECISISON , you need to run one concentration sample run in replicate or three sample having same concentration, run each sample in triplicate and determined the % rsd for given sample and corrected value for triplicate run of three sample. You referring to rugdness of the method wherein different days, different reagent and different instrument, different analyst etc

I hope this will help you