Testing for TFA and excipients
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Many suppliers have lately added the testing for endotoxins, sterility, heavy metals, even for fentanyl to their basic purity and identity. But there may be still something missing.
I have learned that the process of synthetizing the peptides uses Trifluoroacetic Acid (TFA) and that significant residual levels of trifluoroacetates, referred to as "TFA salts" may be present in the lyophilized powder.
"TFA is a byproduct of the cleavage step in solid-phase peptide synthesis. It is corrosive, and at elevated concentrations in research subjects it can cause inflammatory responses and cellular toxicity that compromise experimental data."Some manufacturing companies claim to run an extra step called Counter-Ion Exchange to remove these salts, but I see no publicly available tests for it.
Some compounds like FOXO4-DRI are said to naturally contain an increased amount of those salts so it may be not a minor issue.
Also, it is almost unmentioned anywhere, what are the "excipients" that are used as fillers in the lyophilized peptides. Some are said to use sugars (trehalose, sucrose) or polyols (mannitol, sorbitol). There is also the difference in the amount used. It may explain why there are different reactions to different batches of the same peptides, even though they were tested as pure and clean. Why is there no testing for what else is in the vial and how much? I guess it's important, it is about over 99% of the substance mass in the vials.
There is also an issue with "sealing". Some vials have more vacuum, some less, some don't. I asked the suppliers and they said that some batches are inert gas or nitrogen sealed. There is no mention of it on the product page or in COA, no testing. That could be important and useful too, to avoid the confusions.
Thoughts?
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Just FYI for those that may want to listen- Dave Asprey. YouTube. June 2. Interview with Justin Kirkland. Starts at min 17 when they discuss the process of modern (solid phase) manufacturing of peptides. Kinda cool to hear what happens behind the curtain. Haven't gone down this rabbit hole yet. Anybody else?
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