Chromatography Forum

Hi I hope someone can help me. I have to calculate repeatability for finished product (total impurities).
I ran 6 samples (spiked at the impurity limit) and three controls (unspiked)

Should the total impurities recovered for the run be the sum of total impurities for the six samples - the average total impurities in the control samples or is it the sum of total impurities in the six samples+the average total impurities in the control samples.

Thanks

Martina

Do whatever your protocol or SOP says!

If you have no protocol or SOP for this, then, for heaven's sake, write one to avoid the next person having the same problem/question.

Repeatability, by definition, is run on the same sample. Therefore, for this purpose, you ignore your "controls", since they have different levels from the spiked samples.