Blood work is only useful as a tool for individuals to see where they stand. A legitimate lab can never use this method to verify their products. Unfortunately, these days, the research chem companies don't provide much documentation on the purity/composition of their products. It's an unregulated industry, so they aren't required to verify anything. In theory, every company that sells peptides should be using mass spectrometry or spectrophotometry to make sure their compounds are correct, but I suspect few do because of the cost associated. Researchstop.com used to send a quality verification sheet with every order, but they don't anymore.
This is the inherent risk to using peptides or compounds "intended for research purposes ( not for human use)"