Subject: Why COA Net Content Matters Even More With Peptide Blends
From: Derek from Research Radar <[email-masked]>
To: [email-masked]
Date: Tue, 14 Apr 2026 05:08:09 +0000
List-Id: <derekpruski.substack.com>

View this post on the web at https://derekpruski.substack.com/p/why-coa-net-content-matters-even

For research purposes only. Not for human consumption. Not medical advice.
First, what is net content and why does it matter?
When a vendor sends a vial to a third-party lab for testing, the COA will show more than just purity. It also shows how much peptide is actually in the vial — that’s the net content. This number matters because the label isn’t always accurate.
A vial labeled 5 mg might actually contain 4.6 mg or 5.3 mg
That variance is common and not automatically a red flag
But if you don’t check it, your research amounts are based on a number that may not be real
Single peptide vials are easier to work with here — one variance, one adjustment
So what changes with blends?
A simple two-peptide blend like BPC-157 / TB-500 is still manageable. If a vial comes back at 10.2 mg and 11.4 mg instead of the labeled 11 mg / 11 mg, you can account for that and adjust your research amounts. Not ideal, but workable.
The problem compounds when you get into three and four-peptide blends.
Imagine a PE2228 / Semax / Selank / Pinealon blend intended to be 12 / 12 / 12 / 12
If the COA comes back 16 / 11 / 8 / 9, the ratios are completely skewed
Each of those peptides targets a different pathway
You can’t selectively redose one to correct the imbalance — the whole protocol is off
The more peptides in a blend, the more variables a vendor has to control at once, and the more ways it can go wrong
The takeaway
Complex multi-peptide blends are harder to quality control, harder to verify, and harder to course correct when something is off. This is one of the main reasons I generally steer toward singles or simple two-peptide blends in my own research — more control, easier to interpret results, easier to troubleshoot.
Always pull the COA before researching any compound
Don’t just check purity — check net content for every peptide in the blend
If a vendor isn’t testing their blends to the same standard as their singles, take note
Simpler is almost always better when it comes to blend complexity
All content is intended for research and educational purposes only. Not for human consumption. This is not medical advice. Always conduct your own due diligence.

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