How to read a Klow blend COA: four peptides, four identities, four amounts, worked through on lot RN-2610-KLOW

What a Klow COA has to prove#

Klow is a single lyophilized vial that contains four separate peptides: GHK-Cu, BPC-157, TB-500 and KPV. A Certificate of Analysis for a single peptide answers three questions: is it the right molecule, how much of the signal is that molecule, and how much is in the vial. A Klow COA has to answer the first and third questions four times over, once for each component, and it has to do so in a way that lets you check each answer against something. A report that says "identity confirmed" and gives one purity figure for the vial tells you very little about a four-part mixture.

This guide walks through what a multi-component report must show, then reads Renuvia's own published report for Klow lot RN-2610-KLOW line by line, and ends with a checklist that applies to any blend COA, whoever supplied it. For the general anatomy of a report, see how to read a Certificate of Analysis; for what a multi-peptide vial is in the first place, see peptide blends: what a multi-peptide vial is.

The four Klow components and their masses#

Identity by mass spectrometry works by comparing a measured mass with the mass the molecule should have, so the starting point is the expected value for each component. The table lists the reference values used in this guide and where each comes from.

Two points matter for reading a report. First, TB-500 is not thymosin beta-4: FDA's 2026 evaluation describes it as a seven-amino-acid synthetic fragment of thymosin beta-4 from amino acids 17 to 23 and notes in a footnote that the two are not the same substance.^[8] Second, GHK-Cu is a metal complex, and the copper and the peptide are separate questions for an analytical laboratory, which comes up below.

What a multi-component COA must show#

Each component identified separately#

The identity line should name every component, and the mass-spectrometry section should show a spectrum, or at least labelled ions, for each one. A single "identity: confirmed" for the vial does not tell you which of the four were looked for. The principle comes from method validation: FDA's 2024 Q2(R2) guidance describes specificity as the extent to which other substances interfere, and says that for an assay, discrimination of the analyte in the presence of other substances should be demonstrated.^[2] In a blend, each peptide is "another substance" for the other three.

Each component quantified separately#

A blend label is a claim about amounts, so the report should give a measured amount, in milligrams, for each component. Only then can you compare the vial with the label, and only then can you see whether the proportions are what the mixture is supposed to be. A total alone could hide one component at half its intended amount and another at double.

The sum compared with the label#

Add the per-component figures and compare the sum with the label total. A sum close to the label, with each component in proportion, is the pattern you want. A sum well above or below the label, or proportions that drift, is a question to put to the supplier.

Why the measured total can exceed the label#

A measured total a few percent above the label is common and is not, by itself, a sign of a problem. Several things contribute, and a report rarely says which applies:

• Fill tolerance. Filling is done by weight or volume with a tolerance, and a filler may aim slightly above the label so that vials do not come up short.
• Measurement uncertainty. Every quantitative figure carries an uncertainty that depends on the reference standard, the calibration and the sample handling. The Eurachem/CITAC guide sets out how laboratories estimate and express it.^[4] A COA that gives a single figure with no uncertainty is still a measurement with one.
• Basis of the figure. A content figure can be calculated against a reference standard as free peptide or as a salt, with or without counter-ion and water. If the label and the measurement use different bases, they will differ. The TFA and counter-ion guide explains how salt form changes the numbers.
• Method range. Quantitative methods are validated over a range around the declared content. The Q2(R2) guidance gives 80% to 120% of declared content as the reportable range for an assay.^[2] That is the span a method is built to measure, not an acceptance limit, but it shows that a figure a few percent above 100% sits well inside what the method is designed for.

What HPLC purity means for a blend#

For one peptide, HPLC-UV purity is the share of the ultraviolet signal in the chromatogram that belongs to the main peak. For a blend, the laboratory sums the peaks it has assigned to the named components and expresses them as a share of all the signal. The figure therefore answers "how much of what the detector saw is one of the four intended peptides", and nothing else.

It does not tell you the ratio between components. Peptides absorb ultraviolet light to different degrees: Kuipers and Gruppen measured the contribution of each amino acid at 214 nm and found, for example, that tryptophan absorbs about 30 times more than a peptide bond and phenylalanine, tyrosine and histidine about six times more.^[3] Two peptides present in equal milligrams therefore give peaks of different sizes. Peak heights in a blend chromatogram are not a picture of the proportions; the milligram figures are. The purity misreadings article covers the other ways a single purity number is over-read.

Worked example: Klow lot RN-2610-KLOW#

Renuvia's report for this lot is published in the COA library and linked from the Klow product page.^[1] It was issued by Freedom Diagnostics Testing, which received the sample on 10/29/2026 and reported on 10/31/2026. The method line reads: HPLC with UV detection coupled with mass spectrometry (LC-MS).

The header: tying the report to the vial#

The header names the client (Renuvia Labs) and carries a laboratory accession number, 2610291406, and a search code, Renu2610291406. The laboratory's Lot field reads "Clear Cap", which is the description of the vial as submitted, not Renuvia's lot code; the COA library entry links this accession number to lot RN-2610-KLOW. When a report identifies the sample this way, the accession number is the thing to quote if you contact the laboratory, as described in how to verify a COA is genuine.

Identity: four components named, four spectra#

The identity line reads "GHK-Cu/KPV/TB-500/BPC-157", and the Mass Confirmation section shows a separate spectrum for each. Comparing the labelled ions with the reference masses above:

The figures agree to within a few tenths of a mass unit, which is the kind of agreement expected from a routine instrument reporting to one decimal place. A higher-resolution report would quote more decimals; the question to ask of any report is whether the stated ions are the ones the molecule should produce, and here they are.

Content: each component in milligrams#

The Net Content section gives a figure for each component:

The label on the vial states 80 mg per vial and does not print a per-component split, so the check available from the label is the total: 84.95 mg measured against 80 mg labelled, about 106%. The measured amounts fall close to a 50 : 10 : 10 : 10 mg split, but because that split is not printed on the label, this report cannot be checked against it, and this guide does not present it as a label claim. What the report does show is that all four components are present in measurable, separately reported amounts, and that GHK-Cu is the largest by a wide margin.

Purity: 99.69% of the UV signal#

The reported purity is 99.69% by HPLC-UV. The chromatogram shows four labelled peaks, GHK-Cu first, then KPV, TB-500 and BPC-157, with little else above the baseline. Read in light of the section above, the figure says that almost all of the ultraviolet signal belongs to one of the four named peptides. It does not say that the four are present in a particular ratio; the milligram figures do that. Note also that the GHK-Cu peak is the tallest, which fits it being the largest component by mass, but peak size alone would not prove that, for the absorbance reasons above.

What this report does not include#

Like most research-peptide COAs, this report covers identity, HPLC-UV purity and measured content. It does not report counter-ion content, water content, endotoxin, or copper content. That is not a defect in the report, but it is the boundary of what the report can be cited for. FDA's 2026 evaluations of BPC-157 and TB-500 make the same observation about the certificates typically available for those substances: FDA found that public BPC-157 certificates typically report only purity, with no impurity limits, and that an example TB-500 certificate covered identity and purity but not assay, impurities or endotoxin.^[7][8] Endotoxin is covered in the endotoxin and LAL testing guide.

A checklist for any Klow or blend COA#

1. The product line names the blend and its total, and the report is for the blend, not for one of its ingredients shown in its place.
2. The identity line names every component, and the mass section shows labelled ions for each one.
3. The labelled ions match the expected masses for each component, within the precision the report quotes.
4. Net content is given in milligrams for each component, not only as a vial total.
5. The components add up to a total you can compare with the label, and the gap is explainable (a few percent, not tens of percent).
6. The proportions between components match the blend's stated composition, where the label states one.
7. The purity figure is read as "share of UV signal in the named peaks", not as a statement about ratios.
8. For a metal complex such as GHK-Cu, you know whether the metal was measured or only the peptide.
9. The header carries a laboratory accession number and dates, and you know how the report is linked to the lot on your vial.
10. You know what the report leaves out (counter-ion, water, endotoxin) and whether your work needs any of it.

Every Renuvia lot with an issued report is listed in the COA library; lots awaiting a report show as pending rather than carrying a figure from another source. The worked example above can be repeated against the PDF itself, which is linked from the library entry for lot RN-2610-KLOW.