How many samples do you need to analyze for effective blood plasma products quality control?

The number of samples needed for effective blood plasma product quality control depends on various factors, including regulatory requirements, batch size, and the desired level of statistical confidence. Typically, quality control protocols involve testing a representative sample from each batch to ensure safety, purity, and potency. Regulatory agencies may specify sample size guidelines to ensure robust quality assessments in the production of blood plasma products.

Calculating the sample size needed for a given purpose depends on your target objective; you can either reason on power when your objective is testing a difference between two or more products/protocols/groups or about accuracy of the mean or proportion of the variable you are measuring. I guess from you question that you are in the second situation. You want to ensure that you protocol (machine, ..) measures accurately the variable (e.g. sterility) you are interested in. In this cas what you care about, is the standard error of your parameter of interest (mean or proportion or sometimes variance). There are formulas that allow you to compute sample size for a given accuracy , that you can find in any good statistics book. 
If you have to meet a standard (for example compare you measures with your own protocol or machine with those from a gold standard protocol), you are in a hypothesis testing situation and you can reason on power. 
There are many tools that can compute sample size for a given power and expected/tolerated difference. if you familiar with R langage try the pwr package.