Method Validation -Repeatability


The repeatability test in USP<1225> should be assessed using a minimum of nine determinations covering the specified range for the procedure.
Usually three concentrations and three replicates of each concentration or using a minimum of six determinations at 100% of the test concentration.

Can some how do we guarantee that a sample is homogenous in formulated mixture?

Is it not more appropriate to make a stock solution and take aliquotes.


Hi jay,
As you have said , you can formulate a stock preparation of your drug product & make serial aliquots.
Repeatability can be assessed by two ways as mentioned in USP<1225>
(I). Six individual determinations @ Target level
(II).Three individual determinations @ Three ranges [3x3=9 Determinations


I have to determine the linearity of the HPLC analytical method suppose that I have the same concentration of the sample and standard. I would like to know how to prepare the samples? calculations, injections? please I have to give back my homework as soon as possible.

Thanks for your kind help