CJC-1295 is the dirtiest peptide we test: 7.8% of vials fail purity (vs 0.14% 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.

The headline

CJC-1295 is the dirtiest peptide we test. Across 683 third-party CJC-1295 assays with a measured purity figure, 53 came back below 90% purity — a 7.76% failure rate, about one vial in thirteen. The mean purity across the whole set is 97.33%, held down by a long tail of badly-made batches. All figures on this page are as of July 2026.

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:

CJC-1295 fails purity roughly 57× more often than tirzepatide and 33× 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 a quarter of 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 12.59%, higher still). We use 90% because it is unambiguous.
• The denominator. Published rows whose peptide is labeled exactly CJC-1295 — the no-DAC / mod GRF 1-29 form that the bare “CJC-1295” label denotes in practice — with a measured purity figure greater than zero: n = 683 (data as of July 31, 2026). Combination vials labeled as blends (“CJC-1295 + Ipamorelin” and its variants) are outside this denominator, because a blend almost never carries a single clean purity number. One caveat we owe you: 28 rows carry the bare “CJC-1295” label but are flagged internally as blends, and they sit inside the 683. Excluding them gives 655 assays, 53 failures, 8.09% — a slightly worse headline, so the figure we publish is the conservative one. We also hold a smaller set of certificates labeled with explicit with-DAC or mod GRF 1-29 suffixes; those are tracked separately and are not in this denominator. (Folding the suffixed variants in would move the count to 865 assays and the failure rate to 6.24% — the variant certificates almost all passed, so including them only dilutes the failure rate; we report the stricter single-label figure.)
• 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 10, 2019 → July 10, 2026, with the failing batches clustering in the first half of 2025. The corpus is heavily weighted to 2025 and 2026: only 24 of the 683 assays carry a test date before 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.

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. This table lists every vendor in our corpus with three or more failing CJC-1295 batches — each row is that vendor’s CJC-1295 assays we hold and the count that fell below 90%, and every row links to that vendor’s worst single documented certificate.

Three of these — Loti Labs, Planet Peptide, 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 683-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 — 8 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 thirteen 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 clear the bar roughly seven hundred and thirty times out of seven hundred and thirty-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 ~8% base rate, a third-party HPLC on a CJC-1295 order is still the best-value test in the whole peptide market. Eight percent is a much better number than nineteen. It is also roughly fifty-seven times the odds you face buying tirzepatide from the same rooms.

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 computed from the TitrateLab COA corpus as of July 31, 2026 (n = 683 CJC-1295 assays, test dates Nov 2019 – Jul 2026). The rate has moved a lot since first publication (18.96% on 269 assays in June 2026, 7.76% on 683 today) because the denominator grew far faster than the failure count; the directional finding, that CJC-1295 fails purity by an order of magnitude more often than any high-volume GLP-1, has held across every snapshot since we started tracking it. The exact queries behind every number above are published alongside this article (cjc-1295-dirtiest-peptide.queries.sql) so any claim can be re-derived against the live data.