All raw materials and finished products are tested for quality and correct finished product dosages.
Correct. The proper GMP processes involve testing raw materials and finished products.
When it comes to USP Labs old products, I don't think that there were many, if anyone, that thought that anything that may have been added was done so unintentionally.
I'm not insinuating anything - I'm straight forward saying that a lot of people over the years have felt like a lot of the original USP Labs products had in them more or different things than what the labels said, and also that many people reported getting dramatically different results from the beginning batches to the later ones.
So when people ask us to do anything that would be comparable to an old USP Labs product, I always state clearly that if the product was what it was supposed to be - meaning that it contains what the labels said, then yes, that is doable. However, I can never guarantee that a product is going to be just like one of their old ones IF they were adding extra things into it.
Yes, a company can very much test to see if things are spiked. It's very simple - that's why raw materials are tested before and after capsulation. If you test raw materials and they are 99% purity, and then you test finished product and it is 750 mg. per capsule by weight and the testing shows its 750 mg. of 99% material, then there's nothing else there. (Of course real calculations would be done with flow materials, but that's just an example as to how its done).