You’ve got two tabs open, Blank Peptides in one and Core Peptides in the other, and both say more or less the same thing: made in the USA, over 99% pure, third-party tested. Both sell a BPC-157 and TB-500 blend, and both sell a GHK-Cu blend with the same two peptides in it. If you were judging on the storefront alone, you’d flip a coin, and honestly that’s how a lot of people end up choosing.
The trouble is that the storefront is the least informative part of a peptide vendor’s website. The parts that tell you something are the ones almost nobody reads: the About page verbs, the certificate PDF buried on a product page, the shipping terms, the blend contents line. Those are where the two companies stop sounding identical, and that’s where I want to spend this comparison.
Full disclosure, we’re Blank Peptides, so one column of this table is ours. I’ve tried to make it fair by quoting Core Peptides verbatim, dating every observation, and giving them credit where their site does something ours doesn’t. You should still check both.
Key takeaways
- The useful comparison between any two peptide suppliers is who synthesized the lot, which lab tested it, what the certificate covers, whether you can see it before buying, and whether blends disclose each component.
- Blank Peptides synthesizes and vials every lot in its own cGMP laboratory and has Freedom Diagnostics and Horizon Analytical test each lot for identity, >99% purity, bacterial endotoxin, and sterility, with the COA public per lot.
- Core Peptides publicly states its products are “synthesized and lyophilized in the United States” and “3rd party tested”, and one blend page links a COA PDF from Vanguard Laboratory reporting HPLC purity of “>99.50%”.
- A named lab in the site prose, mass-spectrometry identity, endotoxin, sterility, and a COA on the single-compound pages I opened were not listed on the pages reviewed 2026-09-08.
- All of this is for research use only, and nothing here is guidance on using any compound in people or animals.
What separates two suppliers that both claim 99% purity?
Let me set out the yardstick before I name anyone, because a head-to-head is only fair if both sides get measured the same way.
The first question is provenance: does the company synthesize the material itself, or does it buy finished product and put its label on it? You find the answer in the verbs. “We synthesize”, “our laboratory”, “our QC” point one way. “We source”, “we supply”, “our partners” point the other. Neither is a crime, but the synthesizer can tell you what happened to the lot between raw material and vial, and the relabeler can only pass along what it was told.
The second is whether the testing lab is named. Any site can print “third-party tested”. A name lets you look the lab up, check that it does peptide analysis, and, if you’re motivated, send your own sample there.
The third is what the test panel covers. HPLC purity is the number everyone quotes, and it’s a real number, but it only says how much of the sample is one thing. It doesn’t say the thing is the right sequence, which takes mass spectrometry, and it says nothing about bacterial endotoxin or sterility. A full panel covers all four. A purity-only certificate covers one.
The fourth is whether a batch COA is viewable before purchase and tied to a lot number that also appears on the vial. If you can’t match paper to glass, the paper is decoration.
The fifth is blend composition. A blend sold by total milligrams with no per-component split can’t be reproduced, so a serious supplier prints the split.
I’m leaving out how long either company says it’s been trading, because it’s unverifiable and it doesn’t tell you anything about the lot on your bench.
How Blank Peptides makes and tests each lot
Blank Peptides operates its own cGMP laboratory in the USA and handles the whole chain in-house: compounding, vialing, finishing, labelling, and quality control. Because no step is outsourced to an unnamed facility, the chain of custody for each lot is one continuous record. The company also contract-manufactures and fulfils for other peptide brands under the same process.
Every lot is tested on a full panel rather than purity alone. Identity is confirmed, purity is reported at >99%, and the lot is tested for bacterial endotoxin and sterility. That testing is done by two named outside laboratories, Freedom Diagnostics and Horizon Analytical, so a buyer can verify the lab as well as the number.
Results for each lot are posted as batch certificates of analysis before purchase, and the lot number on the certificate matches the lot printed on every vial. Lyophilized product carries an expiration of about 24 months.
The catalog is 34 compounds, and every blend discloses its composition per component: GLOW is 70mg made up of GHK-Cu, BPC-157, and TB-500; KLOW is 80mg and adds KPV; Wolverine is 20mg of BPC-157 and TB-500. Processing time is within 1 business day, and orders ship at room temperature, which is the normal condition for lyophilized peptides. The company has been in business for five years.
What Core Peptides publicly states
Core Peptides sells at corepeptides.com. On the pages reviewed 2026-09-08, the homepage states the company has been “Serving the research community for over 7 years, and 3rd party tested”, offers “U.S. lab-tested peptides” that are “independently verified for purity”, and shows “3rd PARTY TESTED” and “US LAB TESTED” badges. The About page states that “All our products are synthesized and lyophilized in the United States”, that “Our peptides are manufactured locally against the highest standards for synthesis, undergoing rigorous quality control measures”, and that purity reaches “levels exceeding 99%+”. It also describes the company as “a chemical supplier” and “not a compounding pharmacy”.
So on provenance, the site’s verbs are “synthesized” and “manufactured locally”. A facility name, a description of the in-house QC steps, or a named manufacturer was not listed on the pages reviewed 2026-09-08. On the lab, the homepage and About page state “3rd party tested” without naming one. The BPC-157 & TB-500 & GHK-Cu 70mg blend page, though, links a Certificate of Analysis PDF, and that PDF names “Vanguard Laboratory”, lists an HPLC-UV/VIS method, reports purity of “>99.50%”, records identity as “Pass – Matches Ref. Standard”, and carries lot C74111 dated 7/22/2026. Endotoxin and sterility lines do not appear on it. 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, Core Peptides discloses the split on some products. 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 without per-component amounts, and several other blend pages in the category showed a total figure only.
Where Core Peptides clearly comes out ahead is range and shipping. Its catalog page states “Showing all 104 results” plus 19 blends, against 34 compounds at Blank Peptides, and its shipping page states “same (business) day shipping for orders placed before 1pm PST Monday-Friday” and “Free Priority USPS shipping on orders over $200 within the US”. If your work needs a compound we don’t carry, that’s a real point in their favour.
Side by side: manufacturing and full-panel testing
| Attribute | Blank Peptides | Core Peptides |
|---|---|---|
| Synthesises in-house | Yes, own cGMP laboratory, full chain of custody | States “synthesized and lyophilized in the United States”; facility and QC process 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%” by HPLC-UV/VIS — verify |
| MS identity | Confirmed on every lot | COA reviewed shows identity by reference standard match; MS not listed — verify |
| Endotoxin and sterility | Tested on every lot | Not listed on the COA or pages reviewed 2026-09-08 — verify |
| Batch COA before purchase | Public per lot at blankpeptides.com/coas/, lot on every vial | One blend page links a lot-numbered PDF; BPC-157 and TB-500 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
- Go to the product page for the compound you actually plan to order and look for a certificate on that page. Note the lot number, then compare it with the lot on the vial when it arrives. A mismatch, or no lot on the vial, is the thing to chase.
- Read the certificate’s method lines. You want an HPLC line for purity, a mass spectrometry line for identity, and separate results for bacterial endotoxin and sterility. Where any of those is missing, ask support whether it exists for that lot.
- Look up the lab named on the certificate. A working analytical lab has an address, a phone number, and a list of services; if you can’t find it, ask the vendor for the lab’s contact details.
- For a blend, write down the per-component milligrams before ordering, and if the page shows only a total, ask for the split in writing.
- Run both suppliers through the supplier verification checklist so each gets graded on the same questions.
Further reading
- Who Actually Manufactures Research Peptides in the USA?
- Which Peptide Vendors Name Their Testing Lab?
- Best Research Peptide Suppliers: Ranked by What They Document
- Which Peptide Vendors Disclose Blend Composition?
Frequently asked questions
How do Blank Peptides vs Core Peptides compare on testing?
Blank Peptides tests every lot for identity, >99% purity, bacterial endotoxin, and sterility at two named labs, Freedom Diagnostics and Horizon Analytical, and posts the COA per lot. Core Peptides states “3rd party tested”, and one COA I found names Vanguard Laboratory with HPLC purity and identity; endotoxin and sterility were not listed on the pages reviewed 2026-09-08.
Does Core Peptides name its testing lab?
Not in the site prose I read on 2026-09-08. The homepage and About page state “3rd party tested” and “U.S. lab-tested” without a name. The COA PDF linked from the 70mg BPC-157, TB-500 and GHK-Cu blend page does name Vanguard Laboratory, so the name exists on at least one document, just not on the pages most buyers will see first.
Which supplier has the bigger catalog?
Core Peptides, by a wide margin. Its catalog page states 104 peptides and 19 blends, while Blank Peptides carries 34 compounds. If your protocol needs something outside a fairly mainstream list, Core Peptides is more likely to stock it, and that’s a legitimate reason to keep them in consideration regardless of the documentation questions above.
Which blends disclose per-component amounts?
At Blank Peptides, all of them: GLOW, KLOW, and Wolverine list each component’s share. At Core Peptides, the BPC-157 & TB-500 blend and the 70mg GHK-Cu blend state per-component milligrams, while the KLOW 80mg page lists components without amounts on the page reviewed 2026-09-08. For any blend without a split, ask before you order.
Are these products for human use?
No. Every compound mentioned here is sold for in-vitro laboratory research only. Core Peptides states its products are “not for human consumption”, and Blank Peptides labels every vial for research use only. This comparison is about documentation and manufacturing claims, and nothing in it is guidance on dosing 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.
