P21: 21 published COA source records

47 studies on P21 curated from PubMed, ClinicalTrials.gov, and EuropePMC. Updated daily.

Bottom line: TitrateLab indexes 21 published P21 COA source records from third-party laboratories, covering 11 publicly attributable vendor identities. Across 18 records with positive numeric purity, the arithmetic mean is 99.12%. 0 records report zero purity; these remain in the record count and are excluded from the positive-purity mean. 0 positive purity results are below 90%; 0 records report measured amount more than 10% below the label. The latest recorded test date is 2026-10-08. TitrateLab did not perform these laboratory tests. Source records are not unique batches, and vendor identity does not establish manufacturing role, product safety or overall quality.

P21 average prices

As of 2026-10-18, vendor-blind retail asking-price averages for the US delivery market, calculated from the same in-stock exact-strength cells as the Peptide Price Index. Shipping is excluded.

Strength Average / vial Observed range / vial Average / mg Coverage
5 mg $37.50 $37.50–$37.50 $7.50 1 source · 1 offer

Asking prices are not manufacturing cost and do not establish product equivalence, quality, safety, or legality. View full price methodology →

P21: published third-party laboratory evidence

All published source records, including absent and zero purity. Matching uses a case-insensitive exact peptide token. No deduplication in the headline; vendor rankings deduplicate eligible certificates separately. The COA archive can use normalized compound names and a different measurement or duplicate policy; totals from these populations need not match.

Latest recorded test: 2026-10-08. Aggregate calculated: 2026-10-18T04:26:33.898871+00:00. Calculation time is not a laboratory observation date.

Within that total, 4 source records have unresolved vendor identity. They remain in corpus-level lab evidence and are excluded from named-vendor rankings.

99.12%
Mean positive purity
0
Records reporting zero purity
21
Published source records
11
Public vendor identities

Top 3 vendor evidence profiles for P21

Eligible vendors have at least 2 deduplicated certificates and 2 classifiable identity observations. Rank uses the 95% lower confidence bound on clean identity results; mean positive purity and certificate count break ties. Missing measurements are not passes. Exact-zero/not-detected and explicit wrong-compound markers count once per adverse certificate. This describes submitted-sample evidence, not every product or shipment, and is not an endorsement.

RankVendorDeduplicated certificatesAvg positive purityIdentity adverse results
#1 5 98.87% 0 of 3 (0.0%) 0 0% / not detected · 0 wrong compound · 2 unclassified Reveal with Pro →
#2 2 99.22% 0 of 2 (0.0%) 0 0% / not detected · 0 wrong compound Reveal with Pro →
#3 2 99.12% 0 of 2 (0.0%) 0 0% / not detected · 0 wrong compound Reveal with Pro →

Vendor identities are included with Pro. Record counts and lab measurements remain visible.

Recent source records: #118540 (99.33%) · #116220 (99.26%) · #115971 (99.26%) · #114470 (99.15%) · #107804 (99.19%) · #103160 (99.08%)

P21 studies and clinical research

Research tools

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Reconstitution calculator Bac water, concentration & insulin-unit math Verify a COA Look up a report number against our corpus