Every peptide vendor says the same three words: third-party tested. The phrase costs nothing to print and most buyers have no way to check it. This page is the checking procedure. Five things to look at, in order, and what each one actually proves.
Direct answer: A vendor is verifiable when you can take the lot number printed on the vial in your hand, find that exact lot in a published certificate of analysis, and see a named laboratory on the report. If any link in that chain is missing, the testing claim cannot be checked, whatever the website says.
The five checks, in order
Check 01
Is there a certificate of analysis at all?
Start with whether a document exists and whether you can read it before you pay. A vendor who emails a COA only after an order, or on request, has made the claim unfalsifiable at the moment you needed it. Published beats available.
Check 02
Does the lot number on the report match the vial in your hand?
This is the check that does the most work, and it is the one almost nobody performs. A certificate covers one batch. If the report says lot PS07-TSM10 and your vial says something else, that report describes material you did not receive. Peptides are made in discrete batches and quality moves batch to batch, so a report without a matching lot is a report about somebody else's vial.
Check 03
Is the testing laboratory named?
"Independent third-party lab" is not a name. A real report carries the laboratory that ran it, which means you can look that laboratory up, and it means the lab has something to lose by signing. Look for accreditation as well. ISO/IEC 17025 is the international standard for testing and calibration laboratory competence, and it is the relevant one here.
Check 04
What was actually tested?
Purity is the number everyone quotes and it answers only one question. A purity figure tells you what fraction of the material is the intended compound. It says nothing about whether the compound is the right one, whether the vial is sterile, or what else is in there. Identity, sterility, endotoxins and heavy metals are separate assays and a purity-only report is silent on all of them.
Check 05
Is anything graded independently?
Testing and grading are different jobs. A laboratory produces numbers. A grading body reads those numbers against a standard and assigns a result the vendor does not control. Finnrick performs this role for the research peptide community. When a vendor submits to outside grading, the interpretation stops being theirs.
How to read a certificate of analysis
Most COAs put four or five assays on one page and the acronyms do the hiding. Here is what each one is answering.
- HPLC purity. High-performance liquid chromatography separates the sample into its components and measures how much of it is the target compound. This produces the percentage figure.
- LC-MS or MS identity. Mass spectrometry confirms the molecular weight, which is how you know the compound is what the label says rather than a cheaper peptide of similar appearance.
- LAL endotoxin. The limulus amebocyte lysate assay detects bacterial endotoxin. Reported in EU/mL, lower is better.
- ICP-MS heavy metals. Inductively coupled plasma mass spectrometry screens for metal contamination. USP General Chapter <233> sets the reference limits.
- Sterility. Tests whether anything is growing in the vial. Separate from both purity and endotoxin.
A report that shows one of these and calls itself a full panel is showing you one fifth of the picture.
Red flags
No lot number anywhere. Not on the vial, not on the report. Nothing can be matched, so nothing can be verified.
One certificate covering the whole catalog. A COA describes a batch of one compound. A single document standing behind twenty products is not a COA.
A purity claim printed on the label. Labels are printed in runs of hundreds and cannot track a batch. A label reading 99% will eventually sit on a vial that tested lower, because the printing happened before the testing did. The number belongs on the report, tied to the lot.
An unnamed laboratory. If the report will not say who ran it, there is no one standing behind the result.
Testing dates that never change. New batches need new reports. A test date frozen a year in the past means current stock is uncovered.
Where Reddit helps, and where it does not
Community threads are good at one thing: catching vendors who took money and shipped nothing. Fulfilment failures are visible, repeated, and easy for strangers to confirm, so the crowd is reliable there.
The crowd is far weaker on purity. Almost nobody posting has independently tested what they received, so the typical vendor recommendation is a report on shipping speed and packaging wearing the language of quality. Use the threads to rule out vendors who do not deliver. Use lot-matched documents to judge what is in the vial. They answer different questions.
Are research peptides legal in the United States?
Research peptides sold for in vitro laboratory use are not FDA approved for human use, and most are not approved drugs at all. They are sold as research chemicals, which is why compliant vendors label them for research use only and not for human consumption. Buying materials designated for laboratory research is a different matter from the approved-drug supply chain, and reputable suppliers keep that distinction explicit rather than blurred. Next Level Labs sells strictly for in vitro research use.
Our own reports, so you can run the checks on us
A page about verification is worth nothing if the vendor writing it will not submit to the same procedure. Every lot below is published, lot-matched, and attributed to the laboratory that ran it. Five independent laboratories appear across the catalog. Bacteriostatic water runs a different panel to the peptides, checking identity, sterility, endotoxins, pH and benzyl alcohol conformance rather than HPLC purity, which is why it carries no percentage.
| Compound | Lot | HPLC purity | Laboratory |
|---|---|---|---|
| Wolverine Stack (BPC-157 + TB-500) | PS07-BCTB20 | 99.94% | ILS Laboratories |
| GLOW | 081026 | 99.96% | Bioviridian |
| KLOW Blend | 080426 | 99.93% | Freedom Diagnostics |
| SS-31 | 082526 | 99.80% | Freedom Diagnostics |
| MOTS-C | PS07-MS40 | 99.79% | ILS Laboratories |
| Kisspeptin-10 | ki5674554 | 99.78% | MDx BioAnalytical |
| CJC-1295 with DAC | cjwd09080 | 99.76% | MDx BioAnalytical |
| Glutathione | gtt154356 | 99.73% | MDx BioAnalytical |
| GLP-2 TZ (Tirzepatide) | PS07-T210 | 99.72% | ILS Laboratories |
| Retatrutide 10mg | PS07-R310 | 99.52% | ILS Laboratories |
| CJC-1295 + Ipamorelin | PS07-CJIP10 | 99.46% | ILS Laboratories |
| NAD+ | PS07-NAD500 | 99.45% | ILS Laboratories |
| KPV | PS07-KPV10 | 99.44% | ILS Laboratories |
| Epithalon | 062226 | 99.42% | Freedom Diagnostics |
| GHK-Cu | PS07-GHK100 | 99.34% | ILS Laboratories |
| Retatrutide 20mg | PS07-R320 | 99.20% | ILS Laboratories |
| Tesamorelin | PS07-TSM10 | 98.04% | ILS Laboratories |
| Bacteriostatic Water 30mL | EB61901 | n/a | Chromate |
Tesamorelin lot PS07-TSM10 came back at 98.04%, the lowest figure in the table and the only one below 99%. It is published at the number it tested at. A vendor who only ever shows you their best lot is showing you a selection, not a record.
Run check 02 on us. Take the lot number printed on any Next Level Labs vial and find it in the report library. If a lot on the glass is not published there, do not use it, and tell us.
See the lab reports.Related reading
The mechanics of reading a report in more depth are in How to read a peptide COA, and the grading standard is covered in Finnrick grading explained. Every published report lives in the Lab Reports library, and sourcing questions are answered on the FAQ.
REFERENCES
- International Organization for Standardization. ISO/IEC 17025:2017, "General requirements for the competence of testing and calibration laboratories." (accreditation standard)
- United States Pharmacopeia. General Chapter <233> Elemental Impurities, Procedures. (heavy metal reference limits)
- United States Pharmacopeia. General Chapter <85> Bacterial Endotoxins Test. (LAL methodology)
- U.S. Food and Drug Administration. "Research Use Only and Investigational Use Only Products," guidance on RUO labeling and distribution. (regulatory framing)
For in vitro research use only. Not for human consumption. Not evaluated by the FDA. Not intended to diagnose, treat, cure, or prevent any condition. This page describes sourcing and documentation practices and is not medical advice.