I need to use a statistical test which enables me to say with a given certainty whether or not there has been increase in the concentrations following the process. This can be done using the student’s t-test, which I have used before.

However, I am unsure how many samples and sub-samples I would need to take and analyse, given the size ratios given above. If the number of samples is dictated by the desired probability (e.g. 95 %, 99 %), how do i go about choosing the correct probability for these particular experiments?