Best Epithalon Source: $0.98 a Micromole, 17 Points Withheld

Five factors, weighted by how much each changes what a buyer can actually calculate or verify, not by how loudly the market advertises it.

Two things about that table are worth defending. Testing takes the largest share because it is the only factor that fails invisibly: a short fill shows on a balance, a slow dispatch shows in tracking, an opaque price shows at checkout, and contamination shows nowhere. And cost is scored on whether the rate is checkable rather than on whether it is low, so a transparent vendor scores full marks at $2.50 or at $6.00 a milligram. Our Selank source ranking weights the same market differently, because that compound has two certificates to compare and this one has a single lot.

Because it is the denominator, and an unverified denominator makes every other number on this page decorative.

The certificate for batch 15-05260628 states a specification of 10 mg plus or minus 10 percent, which allows 1.0 mg in each direction and sets a passing window from 9.00 mg to 11.00 mg. The measured result is 9.64 mg, so the vial is 0.36 mg under its label while sitting 0.64 mg above the floor. It passes and it is short, and both facts come from the same row.

Full marks here, 25 of 25, and the reason is not that the result was good. It is that the vendor measured when nobody would have checked, and then published a number that makes its own advertised rate 3.6 percent worse. The same vendor's February 2026 Selank certificate reports 12.29 mg in a 10 mg vial, roughly 23 percent the other way, which is what a genuine measurement distribution looks like. A supplier whose published masses never deviate from the label is a supplier that is not weighing anything.

Scope is not the same as possessing a certificate, so the 30 points are allocated across the rows rather than awarded for the document existing.

• Purity, 99.312% against a stated minimum of 98%. Reversed-phase HPLC on a C18 column with diode-array detection at 214 nm. Method named, specification stated, value printed. Full credit.
• Identity by LC-MS. The check that stops a clean purity figure from describing a cheaper peptide of similar mass. Full credit.
• Endotoxin, PASS against a 0.5 EU/mL limit. Partial credit only. It prints a verdict rather than a value and names no method, where the compendial reference for bacterial endotoxins testing is USP Chapter 85. A certificate naming that method with a figure in EU/mL says how much headroom the lot had; PASS says only that it was under a line.
• Sterility screen, no growth. Partial credit. A screen is shorter and less demanding than a compendial sterility procedure.
• Heavy metals, negative for arsenic, cadmium, lead and mercury. Partial credit, because negative is a verdict where a figure against a limit would be a measurement.

That lands at 21 of 30. The reason the deduction is real rather than pedantic sits in the only substantive thing FDA has written about this compound: that drugs containing epitalon may pose a risk for immunogenicity for certain routes of administration because of the potential for aggregation and peptide-related impurities, and that the agency lacks sufficient information to know whether the drug would cause harm if administered to humans. Aggregation and impurities are measurable. Three of the five rows above answer with verdicts where numbers were available.

The listing costed above, scored factor by factor, with the withheld points named so the argument can be about the marking rather than the total.

An 83 is not a recommendation to stop reading. It is a claim that five rows can be checked in about ten minutes, and that the seventeen missing points are itemised above instead of rounded away. The same exercise on a compound with two laboratories reporting is on our Semax source ranking.

Price takes 20 of the 100 points, and it is still worth doing the division properly, because comparing research peptides on dollars per milligram quietly compares different numbers of molecules.

This tetrapeptide has a molecular weight of 390.35, roughly half that of the two neighbouring Russian peptides from the same vendor, so a milligram of it contains roughly twice as many molecules. Both figures below are simply mass and molar arithmetic, and neither is a claim about equivalence, potency or effect.

On labelled mass Epithalon is the middle of those three and slightly dearer than Selank. Divide instead by micromoles and it is the cheapest of the three by a wide margin, at roughly $0.98 per micromole against $1.79 and $2.44. On the certificate's 9.64 mg that becomes about $1.01. None of that makes it a better purchase; it makes the units explicit, which is the only honest way to compare a 390 dalton peptide against an 814 dalton one. Our NAD+ source ranking runs into the same unit problem from the other direction, where material is sold by the gram.

A ranking is only honest if it says in advance what would change it.

• Would raise it. An endotoxin result printed as a value in EU/mL with the method named, which is most of the nine missing testing points on its own. Compendial sterility testing instead of a rapid screen. Metals reported as figures against limits. A second certificate on a second batch, worth most of the three points withheld on traceability.
• Would lower it. A vial arriving with a lot code that no published certificate names. Human-use language appearing in the product copy, which would discount every other figure on the page including the certificate link. A measured net content drifting below the 9.00 mg floor of the stated window.
• Would not move it at all. A larger discount, a faster courier, a redesigned listing, more reviews or a longer trading history. None of those produce a number, and every point above is built from a number a reader can check.

Two limits on the whole exercise, both worth more than the score. A certificate covers a sampled aliquot on a stated date, here 23 May 2026, before filling, capping and transit, so it is evidence about a production run rather than a promise about a vial. And no score converts research material into a drug product: comparing purity and EU/mL between sellers is a reasonable way to choose between two laboratory chemicals, and it clears nothing whatsoever for use in a person. Nothing on this page is dosing or medical guidance.