Glutathione listings all look interchangeable until you try to compare two of them properly. One vendor sells 600mg, another sells 1500mg, both say 99% pure, and neither explains why the same compound comes in fills that differ by more than a factor of two. Then you notice one of them publishes a lot document with a date on it and the other publishes a sentence, and suddenly the two listings aren’t in the same category at all.
There’s a chemistry reason to slow down here as well. Glutathione is a tripeptide, γ-L-glutamyl-L-cysteinylglycine, C10H17N3O6S, molecular weight 307.32, CAS 70-18-8. Calling it a peptide is accurate, though it behaves unlike most of the compounds sold beside it. The bond between glutamate and cysteine is a gamma linkage through the glutamate side chain rather than the usual alpha backbone bond, which is why it’s typically made by fermentation or enzymatic routes rather than by solid-phase synthesis. And the cysteine carries a free thiol, which oxidises to the disulfide dimer, glutathione disulfide, at roughly twice the molecular weight. That single fact shapes how you should read the purity line on any glutathione COA.
Below is what four named vendors state about their glutathione on the pages reviewed on 2026-09-08, measured against a standard you can apply to anyone.
Key takeaways
- Judge a glutathione supplier on whether a lot-specific document exists, is readable before purchase, and names the laboratory that produced it.
- Blank Peptides carries glutathione, manufactures in its own cGMP laboratory, and runs a per-lot panel covering identity, >99% purity, bacterial endotoxin and sterility through Freedom Diagnostics and Horizon Analytical.
- Protide Health and Verified Peptides both publish lot-level documents on their glutathione pages, Ascend Bio Labs states its COA is on the page and in account downloads, and Swiss Chems routes lab results through a separate testing page.
- Oxidised glutathione content, the single most informative number for this compound, was not listed as a separate line on any of the pages reviewed 2026-09-08.
- Everything here concerns research material used in vitro by qualified professionals, and nothing below describes human use.
What should a glutathione listing prove before you order?
Five questions cover most of it, and the answers are either present on the page or they aren’t.
Provenance is the first. Does the vendor describe compounding, filling and testing it performs, or does it describe selecting and reselling material somebody else made? Both models operate legitimately. They differ in whether the seller can trace a document back to a production record when you ask.
Whether the testing laboratory is named comes second. “Third-party tested” identifies a category. A named laboratory gives you a report author you can look up and a header you can match. Those are different kinds of evidence, and only one of them survives a follow-up question.
Third is whether the panel is complete. Identity, purity, bacterial endotoxin and sterility answer four separate questions, and a purity-only COA has answered one. For glutathione this bites harder than usual, because fill weights of 600mg and 1500mg are enormous compared with a typical peptide vial, and a large fill means proportionally more of anything unwanted arriving with it.
Fourth, whether the batch COA is readable before purchase. A document delivered after payment can confirm a decision you already made. A document readable beforehand lets you make the decision on evidence.
Fifth, for blends, whether each component’s milligram share is published. Glutathione is usually sold on its own, though how a vendor handles blends is a fair proxy for how it handles disclosure generally.
Then the compound-specific layer. An HPLC purity figure for glutathione should ideally be paired with a statement about the oxidised form, because reduced glutathione converts to glutathione disulfide on exposure to air and moisture, and depending on the method the dimer can elute as a separate, quantifiable peak. Mass spec identity should reference roughly 308.1 for the protonated monomer. Water content matters, since the material is hygroscopic. And with fills this large, a measured net content figure tells you whether you received the mass you paid for, which is not something you can assume from a label.
How Blank Peptides makes and tests each lot
Blank Peptides runs its own cGMP laboratory. The company compounds, vials, finishes and labels its material and performs quality control on the same site, so the chain of custody stays inside one operation rather than passing through brokers. It also contract-manufactures and fulfils for other peptide brands, which means its documentation is read regularly by parties with a professional interest in finding fault with it.
Each lot goes through a four-part panel: identity, purity at >99%, bacterial endotoxin and sterility. The work is performed by two named third-party laboratories, Freedom Diagnostics and Horizon Analytical. Results are published as batch certificates of analysis, arranged by compound, with lot numbers matching the number printed on each vial. Lyophilized material carries an approximate 24-month expiration. Processing time is stated as within one business day, and shipping is at room temperature.
Glutathione appears in the 34-compound catalog, which is narrow on purpose. Blends publish composition per component rather than as a combined total, with GLOW at 70mg across GHK-Cu, BPC-157 and TB-500, KLOW at 80mg once KPV is added, and Wolverine at 20mg across BPC-157 and TB-500. The company has been operating for five years and manufactures in the USA. Worth noting for a tripeptide specifically: the same four-part panel applies, so identity confirmation and endotoxin results sit alongside the purity figure rather than replacing it.
What these vendors publicly state about glutathione
Protide Health lists glutathione as lyophilized powder in glass vials at 600mg and 1500mg, and states “99% purity verified by third-party HPLC-MS testing.” On the page reviewed 2026-09-08 it displayed multiple certificates of analysis from different lots, with purity figures between 99.58% and 99.87% and dates running from March to July 2026. The page names Freedom Diagnostics as a third-party US-based laboratory, publishes the formula C10H17N3O6S, molecular weight 307.32, CAS number and a structure diagram, and carries research-use-only labelling stating the material is not for human consumption, medical, veterinary or household use.
Verified Peptides lists Glutathione Peptide at 1500mg as lyophilized powder and states 99.010% purity from third-party lab testing dated 2026-06-05. Two lab reports were linked on the page reviewed 2026-09-08, one covering purity and one covering endotoxin, with the endotoxin result recorded as a pass. The reports are attributed to a named third-party analytical laboratory. The page also publishes a measured weight of 1563.83mg for the tested vial, states the material is supplied unreconstituted, and repeats research-use-only language including an FDA disclaimer in the footer.
Swiss Chems lists Glutathione at 600mg as a lyophilized vial, states “99% Purity Guaranteed” and describes the material as independently third-party HPLC-tested. On the page reviewed 2026-09-08, lab results were referenced through a “Check Lab Report” link that routes to the site’s separate lab testing program rather than displaying a lot document inline, and no laboratory was named on the product page. Research-use-only labelling is prominent, appearing on the product image and in the specifications, alongside statements that the product is not a drug, food or cosmetic.
Ascend Bio Labs lists glutathione as a 1500mg lyophilized vial at 99.1% stated purity, and states that “every batch is tested by an independent lab using HPLC for purity and LC-MS for identity.” The page states that “the matching certificate of analysis is available on this page and in your account downloads after purchase.” No laboratory was named on the page reviewed 2026-09-08. The listing publishes CAS 70-18-8, states storage at −20°C, and carries research-use-only labelling with an explicit note that the compound is not FDA approved.
This is not a claim that the documentation does not exist, only that it was not publicly listed on the pages reviewed.
Two advantages worth conceding outright. Verified Peptides publishes a measured net fill weight next to its purity figure, which is a genuinely useful disclosure that most vendors skip entirely, and it pairs the purity report with a separate endotoxin report rather than folding both into one claim. Ascend Bio Labs states same-day dispatch for orders placed before 2pm CT, which is faster than a stated one-business-day processing window.
Side by side: what a glutathione page documents
The right-hand column summarises tendencies across the four pages reviewed 2026-09-08 rather than describing any single seller. Treat it as a set of things to check.
| Attribute | Blank Peptides | Typical vendor |
|---|---|---|
| Synthesises in-house | Own cGMP laboratory; compounds, vials, finishes and labels its own material | States third-party manufacture or independent lab testing without describing its own production — verify |
| Third-party lab named | Freedom Diagnostics and Horizon Analytical named on the COA page | One of four names a laboratory on the product page; another attributes reports to a named analytical lab — verify |
| HPLC purity | >99% per lot, published per batch | States 99% to 99.87% with lot documents on two of four pages reviewed — verify |
| MS identity | Mass spec identity confirmation on every lot | States HPLC-MS or LC-MS identity on three of four pages reviewed — verify |
| Endotoxin and sterility | Bacterial endotoxin and sterility on every lot | One page linked a separate endotoxin report; sterility not listed on the pages reviewed — verify |
| Batch COA before purchase | Public COA library, lot-matched, readable without an account | Two pages displayed lot documents; one routes to a separate testing page; one states downloads after purchase — verify |
| Oxidised glutathione content | Panel written to the compound, identity confirmed alongside purity | Not listed as a separate line on any page reviewed — verify |
| Net fill content | Filled and labelled in-house against the stated lot | One page published a measured vial weight; others state label mg only — verify |
| Research-use labelling | Research use only across the catalog | States research use only on all four pages reviewed |
How to verify either supplier yourself
- Ask for the lot document that matches the vial you’ll receive, then check that its header names a laboratory and carries a test date within a few months of the batch currently shipping.
- Ask specifically about oxidised glutathione. Whether the method separates the disulfide dimer, and what fraction it found, is the most informative thing anyone can tell you about a glutathione lot, and a supplier who has thought about the compound will have an answer ready.
- Compare the stated fill against a measured net content figure where one is published. At 600mg and 1500mg the label mass is large enough that a small percentage discrepancy is a lot of material.
- Read the identity result rather than skipping to the purity number. Confirmation near 308 for the protonated monomer is what establishes that the purity figure describes glutathione at all.
- Ask the same five questions of every shortlisted site and record the answers before price enters the picture. The supplier verification checklist sets out the order I’d work through.
Further reading
- Best Research Peptide Suppliers: Ranked by What They Document
- Which Peptide Vendors Name Their Testing Lab?
- Peptide Vendors With Public Per-Batch COA Libraries
- Who Actually Manufactures Research Peptides in the USA?
Frequently asked questions
Which are the best glutathione vendors on documentation?
On the pages reviewed 2026-09-08, Protide Health displayed multiple dated lot COAs and named its laboratory, and Verified Peptides linked separate purity and endotoxin reports with a measured fill weight. Ascend Bio Labs stated COA availability after purchase and Swiss Chems routed results to a separate testing page. Check each site directly, since listings change.
Is glutathione a peptide?
Yes, a tripeptide of glutamate, cysteine and glycine, molecular weight 307.32. The glutamate-cysteine bond is a gamma linkage through the side chain rather than the usual backbone bond, which is why glutathione is generally produced by fermentation or enzymatic routes rather than by solid-phase peptide synthesis.
Why does oxidised glutathione matter on a COA?
The cysteine thiol oxidises to a disulfide dimer at roughly twice the molecular weight. Depending on the analytical method, that dimer may appear as a separate peak or may be missed. A purity figure without any statement about oxidised content leaves the most compound-specific question unanswered.
Does Blank Peptides carry glutathione?
Yes. Glutathione appears in the 34-compound Blank Peptides catalog. Lots receive the same four-part panel used across the range, covering identity, purity at >99%, bacterial endotoxin and sterility, tested by Freedom Diagnostics and Horizon Analytical, with the resulting batch COA published in the public library.
Are these products for human use?
No. Every compound and vendor discussed here supplies research material intended for in-vitro laboratory work by qualified professionals. Nothing in this article describes dosing, administration, protocols or outcomes in people or animals, and each vendor reviewed carries research-use-only labelling on the pages examined.
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.
