CJC-1295 is the dirtiest peptide we test: 19% of vials fail purity (vs 0.2% for tirzepatide)
One-line glossary: “purity” here means the percentage of material in the vial that is actually the labeled peptide, as measured by HPLC on a third-party certificate of analysis (COA). 100% is the goal; under 90% means roughly a tenth or more of what you paid for is something else.
- Across 269 third-party CJC-1295 assays (purity measured, Nov 2023 – May 2026), 51 tested below 90% purity — a 18.96% failure rate. Mean purity across the set is just 94.0%.
- That is the worst failure rate of any high-volume peptide in our corpus. For comparison, tirzepatide fails at 0.25% (8 of 3,219) and retatrutide at 0.39% (14 of 3,617). CJC-1295 fails roughly 76× more often than tirzepatide.
- The failures are not marginal misses. Of the 51 sub-90% batches, two assayed below 50% purity and one — a Swiss Chems batch tested April 1, 2025 — came back at 1.69%.
- This is a synthesis problem, not a testing-noise problem: 68 distinct vendors appear in the CJC-1295 set, and the failures cluster in specific batches with documented certificates, not randomly across the corpus.
- Plenty of vendors have no failing CJC-1295 batch documented in our data. The point of this piece is not that CJC-1295 is unbuyable — it's that it is the one peptide where the certificate matters most.
The headline
CJC-1295 is the dirtiest peptide we test. Across 269 third-party CJC-1295 assays with a measured purity figure, 51 came back below 90% purity — a 18.96% failure rate, nearly one vial in five. The mean purity across the whole set is 94.0%, dragged down by a long tail of badly-made batches.
Here is the same sub-90% threshold applied to the two most-tested GLP-1 peptides in our corpus, where the testing volume is more than ten times larger:
| Peptide | Assays (purity measured) | Below 90% | Fail rate | Mean purity |
|---|---|---|---|---|
| CJC-1295 | 269 | 51 | 18.96% | 94.0% |
| Retatrutide | 3,617 | 14 | 0.39% | 99.6% |
| Tirzepatide | 3,219 | 8 | 0.25% | 99.6% |
CJC-1295 fails purity roughly 76× more often than tirzepatide and 49× more often than retatrutide. This is not a gap that disappears with more data — the GLP-1 columns carry an order of magnitude more samples and still sit under half a percent.
That asymmetry is the whole story. The peptide grey market is not uniformly bad; the risk is wildly concentrated by compound, and CJC-1295 is where it concentrates.
Why CJC-1295 specifically
A short note on chemistry, because it explains the data rather than excusing it. Most of what circulates as “CJC-1295” is the no-DAC form (also sold as mod GRF 1-29), a shorter, less stable molecule that is harder to synthesize cleanly and degrades more readily than the rigid, heavily-validated GLP-1 backbones. Tirzepatide and retatrutide are made by a small number of large API houses to a near-pharmaceutical standard because GLP-1 demand justifies the process investment. CJC-1295 has none of that industrial pressure behind it — it is a lower-volume peptide that a wide field of smaller operators make, and the certificates show exactly the spread of competence you’d expect from a fragmented field with no dominant clean supplier. The chemistry makes a clean CJC-1295 harder; the market structure makes it rarer.
Methodology
A few things to be clear about, because this is a named-vendor piece and the framing has to be defensible.
- What “fail” means. A failing batch is one whose measured HPLC purity is below 90% — a deliberately lenient bar (many experienced buyers treat 95% as the real floor; at 95% the CJC-1295 failure rate is higher still). We use 90% because it is unambiguous.
- The denominator. Rows identified as CJC-1295 (including the mod GRF 1-29, with-DAC, and without-DAC variants of the same molecule) with a measured purity figure: n = 269. We exclude blends — “CJC-1295 + Ipamorelin” combination vials almost never carry a single clean purity number, so folding them in would muddy the denominator. Pure CJC-1295 only.
- The sources. Every figure is a third-party certificate of analysis — HPLC/UHPLC assays run by independent labs (Janoshik and others), not vendor self-reports and not our own measurements. We OCR and structure the certificates; we do not generate the underlying numbers.
- The window. Test dates span November 21, 2023 → May 14, 2026, with the failing batches clustering in the first half of 2025.
Every vendor claim that follows sits next to a link to the specific certificate it is drawn from. The certificate is the evidence; the prose only restates what it shows.
The worst documented CJC-1295 batches
These are the ten lowest-purity CJC-1295 certificates in the corpus. Read each as a statement about one tested batch on one date, not about a vendor’s entire catalog. The certificate link is the integer-id permalink to the COA detail page.
| Purity | Vendor (as attributed) | Test date | Certificate |
|---|---|---|---|
| 1.69% | Swiss Chems | 2025-04-01 | /research/coa/1476 |
| 40.15% | Sry Labs | 2025-06-10 | /research/coa/1470 |
| 53.14% | Loti Labs | 2025-03-16 | /research/coa/1431 |
| 54.44% | Swiss Chems | 2025-05-05 | /research/coa/1474 |
| 54.54% | Loti Labs | 2025-05-05 | /research/coa/1429 |
| 54.84% | Injectify | 2025-04-22 | /research/coa/1301 |
| 55.97% | Astro Peptides | 2025-04-22 | /research/coa/1401 |
| 57.25% | Swiss Chems | 2025-05-05 | /research/coa/1475 |
| 59.75% | Deuschem | 2025-06-29 | /research/coa/1404 |
| 60.95% | Loti Labs | 2025-05-05 | /research/coa/1428 |
The worst result is worth pausing on. As tested April 1, 2025, the Swiss Chems CJC-1295 batch at certificate /research/coa/1476 assayed at 1.69% purity — a vial labeled as a 2mg peptide that, by the certificate, contained almost none of it. Two other Swiss Chems CJC-1295 batches tested May 5, 2025 returned 54.44% and 57.25% at /research/coa/1474 and /research/coa/1475. We make no claim about Swiss Chems product sold outside these dates; we report what these three certificates show.
Which vendors the failures cluster around
Failures are not spread evenly. A handful of vendors account for a disproportionate share of the sub-90% CJC-1295 certificates. Each row below is that vendor’s CJC-1295 assays in our corpus and the count that fell below 90% — every figure links to that vendor’s worst single documented certificate.
| Vendor (as attributed) | CJC-1295 assays | Below 90% | Worst documented | Worst certificate |
|---|---|---|---|---|
| Astro Peptides | 8 | 7 | 55.97% | /research/coa/1401 |
| Loti Labs | 5 | 5 | 53.14% | /research/coa/1431 |
| Planet Peptide | 4 | 4 | 76.15% | /research/coa/1382 |
| Swiss Chems | 3 | 3 | 1.69% | /research/coa/1476 |
| Suaway Lab Research | 3 | 3 | 64.51% | /research/coa/1473 |
| Liberty Peptides | 3 | 3 | 77.04% | /research/coa/1427 |
| Injectify | 7 | 3 | 54.84% | /research/coa/1301 |
| Deuschem | 4 | 3 | 59.75% | /research/coa/1404 |
| Sry Labs | 4 | 2 | 40.15% | /research/coa/1470 |
Four of these — Loti Labs, Planet Peptide, Suaway Lab Research, and Liberty Peptides — have no CJC-1295 batch above 90% documented in our corpus at all (every one of their CJC-1295 assays we hold is a failing batch). That is a stronger statement than the failure count alone, and it is exactly the kind of pattern a buyer should check a certificate against before ordering.
The vendors with no failing batch documented
The mirror image matters just as much. Across the same 269-assay set, a number of vendors have no failing CJC-1295 batch documented in our data — every CJC-1295 certificate we hold for them is at or above 90% purity, most of them well above:
- Qing Li Peptide — 18 CJC-1295 assays, none below 90%, mean 99.0%.
- Hk Peptides — 10 assays, none below 90%, mean 98.8%.
- Paramount Peptides — 9 assays, none below 90%, mean 98.1%.
- Skye Peptides — 7 assays, none below 90%, mean 99.0%.
- Peptide Sciences — 6 assays, none below 90%, mean 99.4%.
“No failing batch documented” is not “guaranteed clean” — it is a statement about the certificates we hold, not a warranty. But it is the relevant comparison: in a compound where one vial in five fails, a vendor with a clean documented record on eighteen assays carries a meaningfully different risk profile than one whose only three certificates all failed. The certificates are how you tell them apart.
What to actually do with this
The takeaway is not “don’t buy CJC-1295.” It is that CJC-1295 is the single peptide where buying without a batch-specific certificate is most likely to cost you. For tirzepatide you can be casual and still land above 99% four hundred times out of four hundred and one; for CJC-1295 you cannot. Two habits the data supports: ask for the certificate for the batch you’re buying, not a representative one — Swiss Chems’ three CJC-1295 certificates here span 1.69% to 57.25%, so “we test our product” tells you nothing about your vial; and at an ~19% base rate, a third-party HPLC on a CJC-1295 order is the best-value test in the whole peptide market.
You can browse every CJC-1295 certificate behind this analysis, sorted by purity, on the CJC-1295 research hub, and run any certificate you’re holding through the free COA analyzer to OCR and structure it before you trust it. The corpus that produced these numbers grows as new certificates land — figures in this piece are frozen to the snapshot above (n=269, Nov 2023 – May 2026) and the directional finding has held across every snapshot since we started tracking CJC-1295.