ALBANY, N.Y. – October 23, 2026 – Crescent Bioresearch, a supplier of laboratory compounds, has published the Selank certificate of analysis for lot CBR-SKL-260403-001. The endotoxin result is 13.7 EU per vial against a threshold of 40 EU per vial. The vial holds 10 mg, so the result is 1.37 EU per milligram.
Selank, also known as TP-7 and Tuftsin-Pro-Gly-Pro, sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro, CAS 129954-34-3, is supplied by Crescent Bioresearch as Selank 10 mg for laboratory research.
The Selank page
BTLabs, an independent laboratory in West Palm Beach, Florida, tested the lot on July 30, 2026, using the gel-clot Limulus amebocyte lysate (LAL) test under USP General Chapter 85, Bacterial Endotoxins Test. Endotoxin, the lipopolysaccharide of Gram-negative bacteria, is reported by that test in endotoxin units (EU). The page gives a result of 13.7 EU per vial, a threshold of 40 EU per vial, a sensitivity of 0.25 EU/mL, a test volume of 3 mL and a determination of PASS. The result stands at 34 percent of the threshold.
Per vial and per milligram
Testing laboratories report per vial because the vial is what they receive. Research entities plan per milligram because mass is what they weigh out. The conversion is one division, the result by the fill: 13.7 EU divided by 10 mg is 1.37 EU per milligram. The threshold converts the same way, and 40 EU divided by 10 mg is 4 EU per milligram.
The same threshold, a different allowance
The 40 EU per vial threshold also appears on certificates for compounds filled at 100 mg. For those vials, 40 EU divided by 100 mg is 0.4 EU per milligram. The printed threshold is identical, and the allowance per milligram is ten times smaller.
Two lots can therefore both pass against 40 and differ tenfold in endotoxin per milligram. A 10 mg lot at 30 EU per vial passes at 3 EU per milligram, and a 100 mg lot at 30 EU per vial passes at 0.3 EU per milligram. A research entity weighing 5 mg from each would introduce 15 EU from the first and 1.5 EU from the second. Both certificates say PASS, neither verdict shows the difference, and only the measured result and the fill reveal it.
A school exam shows the same thing
Two exams both set a passing mark of 65 points. One exam is worth 100 points and the other is worth 200. A score of 65 is a solid pass on the first and only about a third of the marks on the second. To compare the two, a teacher needs the score and the size of the exam, not just “pass.”
The Selank lot passed against a threshold of 40 EU per vial. On this 10 mg vial, that limit allows 4 EU per milligram. On a 100 mg vial, the same 40 would allow only 0.4 EU per milligram. The certificate prints the measured value, 13.7 EU per vial, so a research entity can work out the figure per milligram: 1.37 EU.
Why the value is needed
A certificate that reports a pass against 40 EU per vial, with no measured value, cannot be converted to anything. The research entity cannot calculate endotoxin per milligram, cannot estimate the load it will introduce from a given mass, and cannot compare the lot with a lot of a different fill.
For this lot, a research entity has 13.7 EU per vial, 1.37 EU per milligram and a threshold of 4 EU per milligram, and can decide for itself whether those figures meet its requirement. Knowing the load per milligram also lets it judge whether endotoxin, rather than Selank, could account for any part of what it observes. Where the result and the threshold sit on a page from this laboratory is shown on the Selank annotated endotoxin report.
“A per-vial pass is correct, and on its own it is incomplete,” Crescent Bioresearch said. “A research entity plans by mass, and to plan by mass it needs the number. Without it, two certificates with the same threshold can hide a tenfold difference.”
SOURCE DOCUMENTS
Bacterial Endotoxins Test report IF-824-QSA-TR006-BTL261029-07, issued by BTLabs, West Palm Beach, Florida, for Selank lot CBR-SKL-260403-001, tested July 30, 2026, by gel-clot LAL; USP General Chapter 85, Bacterial Endotoxins Test.
ABOUT CRESCENT BIORESEARCH
Crescent Bioresearch is a supplier of laboratory compounds, founded around a framework of critical assessment. It works with research entities nationwide in pursuit of preserving the integrity of scientific research through its transparency approach. Follow the Crescent Discovery Series to dive into the latest breakthroughs and findings within prominent literature.
Find Crescent Bioresearch on Instagram, TikTok, X and Facebook, and every certificate we publish, at crescentbioresearch.com/links.
Selank product page (for research entities): crescentbioresearch.com/selank
Media ContactCompany Name: Crescent BioresearchContact Person: Media RelationsEmail: Send EmailCity: AlbanyCountry: United StatesWebsite: https://crescentbioresearch.com/links
