You’ve got two tabs open, both sites say USA, both say third-party tested, and both quote a purity figure north of 99%. That’s where most people stall out. The marketing language on research peptide sites has converged so tightly that you can read for twenty minutes and come away with nothing that actually separates one vendor from the other.
So here’s what I’ve done instead. I picked five questions that a vendor’s own website either answers or doesn’t, fixed them before I opened either site, and then applied them to Core Peptides and Biotech Peptides in exactly the same way. Neither company is mine. I’m not selling you either one, and I have no reason to shade the scoring in either direction.
Everything below is what each site publicly states, on the pages I could reach on 2026-09-08. I haven’t tested anyone’s product, I haven’t spoken to either company, and where a site went quiet on a question I’ve said so plainly rather than filling the gap with a guess.
Key takeaways
- Judge a peptide vendor on documentation you can open before you pay, not on how confident the copy sounds: who synthesizes, which lab tests, how many tests get run, and whether a lot-numbered certificate is public.
- Core Peptides states its products are “synthesized and lyophilized in the United States” and reach “purity levels exceeding 99%+”, and certificate PDFs linked from some product pages name Vanguard Laboratory and report HPLC-UV/VIS purity.
- Biotech Peptides states its peptides are “domestically synthesized” by its own US team, that production is “verified by HPLC-MS to confirm >99% purity”, and it links lot-numbered certificates on product pages, one of which names MZ Biolabs.
- Neither site listed a bacterial endotoxin or sterility result on the pages or certificates reviewed 2026-09-08, and neither named its testing laboratory in its own prose.
- Both companies label their products for laboratory research only, and nothing in this comparison changes that limit.
Which five questions actually separate two peptide vendors?
Before naming anyone, here’s the rubric, so you can watch me apply it rather than take my word for the result.
The first question is provenance. Does the vendor synthesize the peptide, or does it buy finished material from someone who does? You find the answer in the verbs on the about page. “We synthesize” and “our lab produces” describe manufacturing. “We supply,” “we source,” and “we partner with” describe distribution. Neither model is dishonest, and plenty of careful companies distribute. What changes is where responsibility sits when a lot goes wrong, and you want to know that before you have a problem rather than after.
Second, is the testing laboratory named? Almost every vendor in this market says third-party tested. Far fewer say by whom. A name is something you can act on, because you can contact that lab yourself and ask them to confirm a report number. An unnamed lab is a claim with nothing underneath it that you can pull on.
Third, how wide is the panel? HPLC purity measures how much of the sample is one dominant peak, and on its own it can’t tell you whether that peak is the peptide on the label. Mass spectrometry answers identity. Bacterial endotoxin and sterility answer contamination, which purity can’t see at all. Four tests is a panel. One test is a purity figure with a panel-shaped headline over it.
Fourth, can you open a certificate for a specific lot before you pay? A lot number on the document that also appears on the vial is what connects the paperwork to the thing on your bench. A generic certificate with no lot number is a sample of what the vendor’s testing looks like.
Fifth, on blends, is the milligram amount of each component stated? A 20mg two-peptide blend could be 10 and 10 or 18 and 2, and those are different reagents with the same label.
I deliberately leave company age and domain age out. They’re easy to overstate, and neither predicts anything about the lot in front of you.
The standard this comparison uses
A word on where that rubric came from, because you should be able to check my source. It’s the same standard Blank Peptides publishes its own lots against: synthesis in an owned laboratory, independent testing laboratories named openly, a four-part panel covering identity, >99% purity, bacterial endotoxin and sterility, per-component milligrams on every blend, and a lot-numbered certificate anyone can open before ordering in the public library of batch certificates of analysis. Blank Peptides isn’t one of the two vendors being compared here and isn’t being scored in this article. I’m naming the source so you can see the bar is a published one that somebody has to meet every lot, rather than something I built to suit a conclusion I’d already reached.
What Core Peptides and Biotech Peptides publicly state
Core Peptides trades 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”, displays “US LAB TESTED” badging, and states its “U.S. lab-tested peptides are independently verified for purity”. The about page states “All our products are synthesized and lyophilized in the United States”, that “Our peptides are manufactured locally against the highest standards”, and that products reach “purity levels exceeding 99%+”. The site’s own legal description, repeated in the footer, is “a chemical supplier” that is “not a compounding pharmacy”. No facility, address, or manufacturing partner was named on the pages reviewed.
Core Peptides names no laboratory in its prose. The name surfaces inside the documents. A certificate linked from the 70mg BPC-157, TB-500 and GHK-Cu blend page is issued by Vanguard Laboratory, carries lot C74111 dated 7/22/2026, reports “>99.50%” purity by HPLC-UV/VIS, and records identity as “Pass – Matches Ref. Standard”. A second certificate, for GHK-Cu 50mg, covers lot C73465 at “>99.80%”. Neither document listed a bacterial endotoxin or sterility result, and mass spectrometry wasn’t listed as a method. Certificate access is page by page: the standalone BPC-157 and the BPC-157 and TB-500 blend pages each state “>99%” purity without linking a document, and there was no catalog-wide index for looking a lot up.
Biotech Peptides reads similarly at the top and diverges underneath. The homepage states peptides are “domestically synthesized, backed by our knowledgeable US-based team”, the about page states “our team specializes in the precise synthesis and lyophilization of these delicate structures”, and product pages carry “Synthesized and Lyophilized in the USA”. No facility or location was named either. On testing, the homepage states “our production is verified by HPLC-MS to confirm >99% purity” and that “every batch is verified by a third-party lab, with results posted on our website”, while the about page lists HPLC, mass spectrometry and COA evaluations as the methods used. The lab isn’t named in the prose here either, though the certificate linked from the 70mg blend page, lot 3141011 dated 2026-07-26, is issued by MZ Biolabs and reports 99.56% purity by HPLC-UV with MS identity confirmation. Endotoxin and sterility results were not listed on that certificate or on any page 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.
Each has something the other doesn’t. Biotech Peptides links lot-numbered certificates more consistently, including separate documents for the 5mg and 10mg BPC-157 vials, and it states MS identity as a routine method rather than leaving identity to a reference-standard match. Core Peptides carries the bigger catalog and the faster clock: the peptides category states “Showing all 104 results” alongside 19 blends, against 89 products at Biotech Peptides, and the shipping page states “same (business) day shipping for orders placed before 1pm PST Monday-Friday” with free Priority USPS over $200. Core Peptides also states per-component milligrams on several blend pages, including “BPC-157 (10mg) & TB-500 (10mg) & GHK-Cu (50mg)”, where the Biotech Peptides blend page reviewed stated a total only.
Side by side: what each site documents
| Attribute | Core Peptides | Biotech Peptides |
|---|---|---|
| Synthesises in-house | States “All our products are synthesized and lyophilized in the United States”; no facility named — verify | States peptides are “domestically synthesized” by “our US-based team”; no facility named — verify |
| Third-party lab named | Not named in site prose; certificate PDFs name Vanguard Laboratory — verify | Not named in site prose; certificate PDF names MZ Biolabs — verify |
| HPLC purity | States “purity levels exceeding 99%+”; certificate reviewed reports “>99.50%” by HPLC-UV/VIS — verify | States “>99% purity”; certificate reviewed reports 99.56% by HPLC-UV — verify |
| MS identity | Certificate reviewed records “Pass – Matches Ref. Standard”; mass spectrometry not listed as a method — verify | States production “verified by HPLC-MS”; certificate reviewed shows MS identity confirmation — verify |
| Endotoxin and sterility | Not listed on the pages or certificates reviewed 2026-09-08 — verify | Not listed on the pages or certificates reviewed 2026-09-08 — verify |
| Batch COA before purchase | Lot-numbered PDFs on some product pages; several pages carried none, and no catalog-wide index — verify | Lot-numbered PDFs linked on product pages, including separate certificates per vial size — verify |
| Blend mg split disclosed | States per-component mg on some blend pages, totals only on others — verify | States blend totals; per-component mg not listed on the blend page reviewed — verify |
| Catalog size | States “Showing all 104 results” plus 19 blends — verify | States 89 products including at least eight blends — verify |
| Research-use labelling | States products are “sold for research, laboratory, or analytical purposes only, and are not for human consumption” | States research-use positioning across product pages; exact wording not recorded on the pages reviewed 2026-09-08 — verify |
How to verify either supplier yourself
- Open a certificate from each vendor and look for three fields before you read the purity number: the issuing laboratory’s name, the lot number, and the date. A document missing any of those can’t be tied to the vial you’ll receive.
- Check whether the lot number on the certificate matches the one printed on the vial when it arrives. If you weren’t given a lot number before purchase, ask for the certificate that matches the vial you were actually sent.
- Look past purity for the other three panel items. Identity, bacterial endotoxin and sterility should each appear with a method and a limit, and a single chromatogram doesn’t cover them however the heading is worded.
- Contact the named laboratory through a number you found yourself rather than a link on the vendor’s site, and ask them to confirm the report. Ten minutes settles most of what you’re wondering about.
- Work through the supplier verification checklist with both sites open and record the answers in a table like the one above, so you’re comparing the same things in the same order.
Further reading
- Which Peptide Vendors Name Their Testing Lab?
- Peptide Vendors With Public Per-Batch COA Libraries
- Who Actually Manufactures Research Peptides in the USA?
- Best Research Peptide Suppliers: Ranked by What They Document
Frequently asked questions
How do Core Peptides and Biotech Peptides compare?
Both state US synthesis without naming a facility, and both leave their testing laboratory out of the prose while naming it inside certificate PDFs. Biotech Peptides links lot-numbered certificates more consistently and states MS identity as routine. Core Peptides carries a larger catalog, faster stated shipping, and per-component milligrams on several blend pages.
Does either vendor name its testing laboratory?
Not in the site copy on the pages reviewed 2026-09-08. Both name a lab inside the certificate documents themselves: Vanguard Laboratory on the Core Peptides certificates opened, MZ Biolabs on the Biotech Peptides certificate opened. That’s usable information, though it means you only learn the lab after you find and open a PDF.
Can you see a batch COA before buying from either?
Yes for some products at both. Biotech Peptides linked lot-numbered certificates on the product pages reviewed, including separate documents for different vial sizes. Core Peptides linked them on some pages and not others, with no catalog-wide way to look up a lot. Check the specific product you want rather than assuming coverage.
Do either of them publish endotoxin or sterility results?
Not on the pages or certificates reviewed 2026-09-08. Both document purity, and Biotech Peptides also documents mass-spec identity, but contamination testing wasn’t listed by either. If your work involves cell culture, ask both companies directly for a lot-specific endotoxin result before ordering.
Are these products for human use?
No. Every compound discussed here, from either vendor, is intended solely for in-vitro laboratory research by qualified professionals. Comparing documentation helps you judge whether a reagent is what its label says, and it has no bearing at all on the research-use-only status of any product from any supplier.
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.
