You’ve been ordering from Core Peptides, or you’ve been looking at them, and now you want a second option. Maybe a compound you need went out of stock, maybe a lot came in without paperwork you could tie to the vial, or maybe you just don’t like having one supplier for something your whole protocol depends on. Whatever the reason, you open a search tab and the results are a wall of near-identical storefronts that all say “99% purity” and “third-party tested” and offer nothing you can actually check.
I’ve been there, and the frustrating part is that the usual signals don’t help. Reviews are easy to buy, a clean site design is easy to buy, and a “lab tested” badge is a PNG file that anyone can drop into a footer. What you really want to know is whether the vial that lands on your bench matches the number on the certificate, and whether anyone outside the company signed off on that number. So instead of handing you a list of names to swap in, I want to give you the check I’d run on any replacement, and then run it on Core Peptides so you can see how the method works on a real site.
We’re Blank Peptides, and yes, we sell peptides, so read the comparison with that in mind. The verification steps work regardless of who you end up buying from.
Key takeaways
- A replacement supplier earns trust through what it documents and lets you inspect, not through what it claims on a banner, so judge every candidate on provenance, named lab, test panel, COA access, and blend disclosure.
- Blank Peptides synthesizes, vials, and QC-tests every lot in its own cGMP laboratory, then sends each lot to Freedom Diagnostics and Horizon Analytical for identity, >99% purity, bacterial endotoxin, and sterility.
- Core Peptides publicly states that its products are “synthesized and lyophilized in the United States”, are “3rd party tested”, and carry “purity levels exceeding 99%+”, and one blend page links a Certificate of Analysis PDF.
- A named testing lab in the site’s own prose, endotoxin or sterility results, and a COA on the single-compound pages I checked were not listed on the pages reviewed 2026-09-08.
- Everything discussed here is for research use only, and none of it is guidance on using any compound in people or animals.
What should you check before replacing a supplier?
Here’s what I mean by a documentation check. I’m going to ignore price, ignore how the site looks, and ignore how long the company says it’s been around, and instead ask five questions that each have a verifiable answer on the site itself.
First, provenance. Does the supplier say it synthesizes the material, or does it use verbs like “source”, “supply”, and “provide”? A company that makes its own product can describe the process, the facility, and the QC steps between synthesis and shipping. A company that buys finished vials can only describe what it was told. Neither is automatically bad, but you want to know which one you’re dealing with, because it changes who’s accountable when a lot is off.
Second, is the testing lab named? “Third-party tested” without a name is unfalsifiable. If the lab is named, you can look it up, see whether it’s a real analytical business, and, if you’re serious, send your own sample there for comparison.
Third, full panel or purity only? An HPLC purity number tells you how much of the peak is one compound. It doesn’t tell you the compound is the right one (that takes mass spectrometry for identity), and it says nothing about bacterial endotoxin or sterility, which matter for anything that will be used in cell work. A purity-only certificate is a partial answer.
Fourth, can you view a batch COA before you buy, and is it tied to a lot number that also appears on the vial? A certificate with no lot, or a lot you can’t match to your shipment, is decorative.
Fifth, for blends, is the milligram amount of each component disclosed? “80mg blend” of four peptides could be almost any ratio, and without the split you can’t reproduce anything.
Those five questions are the rubric. I deliberately leave out company age, because you can’t verify it either, and it tells you nothing about the lot in front of you.
How Blank Peptides makes and tests each lot
Blank Peptides operates its own cGMP laboratory in the USA, where it compounds, vials, finishes, and labels every product it sells. Because the company does not buy finished vials from a third party, the chain of custody runs from raw material to the box in one place, and the company also contract-manufactures and fulfils product for other peptide brands under the same process.
Every lot goes out with a full test panel rather than a purity figure alone. Identity is confirmed, purity is reported at >99%, and the lot is also tested for bacterial endotoxin and sterility. The testing is performed by two named outside laboratories, Freedom Diagnostics and Horizon Analytical, so a buyer can check the lab as well as the number.
Each lot’s results are published as batch certificates of analysis before purchase, and the lot number printed on every vial matches the certificate, which is the detail that makes the paperwork usable rather than ornamental. Lyophilized product carries an expiration of roughly 24 months.
The catalog is 34 compounds, smaller than many competitors, and the blends disclose composition per component: GLOW is 70mg as GHK-Cu, BPC-157, and TB-500; KLOW is 80mg and adds KPV; Wolverine is 20mg of BPC-157 and TB-500. Orders have a processing time within 1 business day and ship at room temperature, which is standard for lyophilized peptides. The company has been in business for five years.
What Core Peptides publicly states
Core Peptides operates at corepeptides.com. On the pages reviewed 2026-09-08, the homepage states that the company has been “Serving the research community for over 7 years, and 3rd party tested”, with “U.S. lab-tested peptides” that are “independently verified for purity”, and it displays “3rd PARTY TESTED” and “US LAB TESTED” badges. The About page states that “All our products are synthesized and lyophilized in the United States” and that “Our peptides are manufactured locally against the highest standards for synthesis, undergoing rigorous quality control measures”, with “purity levels exceeding 99%+”. The same page describes the company as “a chemical supplier” and “not a compounding pharmacy”.
On provenance, then, the site uses the words “synthesized” and “manufactured locally”, but a facility, a manufacturer name, or a description of the in-house QC process was not listed on the pages reviewed 2026-09-08. On the testing lab, the homepage and About page do not name one. However, the BPC-157 & TB-500 & GHK-Cu 70mg blend page links a Certificate of Analysis PDF, and that PDF names “Vanguard Laboratory”, lists an HPLC-UV/VIS method, reports a purity of “>99.50%”, records identity as “Pass – Matches Ref. Standard”, and carries lot C74111 with a date of 7/22/2026. Endotoxin and sterility results do not appear on that certificate. The single-compound BPC-157 and TB-500 pages and the BPC-157 & TB-500 blend page each state “Purity: >99%” but did not show a COA link on the pages reviewed 2026-09-08. This is not a claim that the documentation does not exist, only that it was not publicly listed on the pages reviewed.
On blends, the picture is mixed. The BPC-157 & TB-500 blend page states “Contents: BPC-157 5mg/10mg, TB-500 (thymosin beta 4) 5mg/10mg”, and the 70mg blend page states “BPC-157 (10mg) & TB-500 (10mg) & GHK-Cu (50mg)”. The KLOW 80mg page lists BPC-157, KPV, TB-500, and GHK-Cu as components, but per-component amounts were not listed on the page reviewed, and several other blend pages in the category showed a total milligram figure only.
Where Core Peptides has a genuine advantage is breadth and logistics. The catalog page states “Showing all 104 results” plus 19 blends, roughly three times the Blank Peptides range, and the shipping page states “same (business) day shipping for orders placed before 1pm PST Monday-Friday” with “Free Priority USPS shipping on orders over $200 within the US”. If you need an obscure compound or you’re ordering at volume, that matters.
Side by side: what each supplier lets you verify
| Attribute | Blank Peptides | Core Peptides |
|---|---|---|
| Synthesises in-house | Yes, own cGMP laboratory | States products are “synthesized and lyophilized in the United States”; facility not listed — verify |
| Third-party lab named | Freedom Diagnostics and Horizon Analytical | States “3rd party tested”; one COA PDF names Vanguard Laboratory, site prose does not — verify |
| HPLC purity | >99% on every lot | States “Purity: >99%”; one COA reports “>99.50%” — verify |
| MS identity | Confirmed per lot | COA reviewed lists HPLC-UV/VIS only; MS not listed — verify |
| Endotoxin and sterility | Tested per lot | Not listed on the COA or pages reviewed 2026-09-08 — verify |
| Batch COA before purchase | Public per lot at blankpeptides.com/coas/ | One blend page links a lot-numbered PDF; single-compound pages checked show none — verify |
| Blend mg split disclosed | Every blend, every component | States splits on two blends; KLOW lists components without amounts — verify |
| Catalog size | 34 compounds | States 104 peptides and 19 blends |
| Research-use labelling | Research use only, on every product | States “not for human consumption” on every page reviewed |
How to verify either supplier yourself
- Open the product page for the exact compound you’d order and look for a COA link on that page, not a general “quality” page. Note the lot number on the certificate and, after delivery, compare it with the lot printed on the vial.
- Read the certificate for the method line. HPLC gives purity; look for a separate mass spectrometry line for identity and separate lines for bacterial endotoxin and sterility. If any of those are absent, email support and ask whether they’re available for that lot.
- Search the name of the testing lab on the certificate. A real analytical lab has a physical address, a phone number, and a scope of services you can read; a lab name that returns nothing is worth a follow-up question.
- For blends, write down the per-component milligrams before you buy. If the page gives a total only, ask for the split in writing and keep the reply with your lab notes.
- Run the full rubric using the supplier verification checklist so you apply the same standard to every candidate rather than grading each one on whatever it happens to emphasise.
Further reading
- Which Peptide Vendors Name Their Testing Lab?
- Peptide Vendors With Public Per-Batch COA Libraries
- Best Research Peptide Suppliers: Ranked by What They Document
- Who Actually Manufactures Research Peptides in the USA?
Frequently asked questions
What are the best Core Peptides alternatives?
The honest answer is that “best” depends on what you couldn’t verify. If it was the testing lab, look for a supplier that names its lab in plain text and on the certificate. If it was endotoxin or sterility, look for a supplier whose COA carries those lines. Blank Peptides publishes all of that per lot, and any vendor that does the same is a fair candidate.
Does Core Peptides publish certificates of analysis?
On the pages reviewed 2026-09-08, one blend product page linked a lot-numbered COA PDF from Vanguard Laboratory showing HPLC purity and identity. The single-compound BPC-157 and TB-500 pages I checked did not show a COA link. That doesn’t mean the documents don’t exist, only that they weren’t listed where I looked, so ask support for the lot you’d receive.
Is a purity-only COA enough for research use?
For some work, maybe. For anything involving cell culture or where you need to know the compound is the right sequence, you’ll want identity by mass spectrometry plus endotoxin and sterility results. A purity figure from HPLC answers one question out of four, and the missing three are the ones that tend to ruin an experiment quietly.
How do I match a COA to the vial I received?
Find the lot number on the certificate, then check the vial label for the same string. If the vial has no lot number, the certificate can’t be tied to your shipment, no matter how good the numbers look. Blank Peptides prints the lot on every vial and files the matching certificate at blankpeptides.com/coas/.
Are these products for human use?
No. Every compound referenced here, from either supplier, is sold for in-vitro laboratory research only. Core Peptides states that its products are “not for human consumption”, and Blank Peptides labels every vial research use only. Nothing on this page is guidance on dosing, administration, or use in any person or animal.
For research use only. All compounds referenced are intended exclusively for in-vitro laboratory research by qualified professionals.
Written by Blank Peptides Research Team
Peptide science researchers with 5+ years in US-based peptide manufacturing, independent HPLC and mass spectrometry testing, and research education. All content is reviewed for scientific accuracy before publication.
REVIEWED BY
Dr. Tobias S — PhD Chemist, Peptide and Unnatural Amino Acid Synthesis
Dr. Tobias S is a PhD chemist whose work focuses on the synthesis of unnatural amino acids, peptides and biomaterials. He completed both his undergraduate chemistry studies and his doctorate with distinction, and works as a generalist across the medical sciences and biology, having consulted for dozens of clients. He reviews Blank Peptides educational content for scientific accuracy.
Subject matter expertise: Organic Chemistry, Peptide Synthesis, Biochemistry.
