Sunday, 11 October 2026 11:11 AM
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The investigators who found the source of their failure fixed it by changing one thing: they bought from a supplier whose certificate printed the number rather than solely providing a pass or fail metric. Across the laboratory compound industry, that number is still the one most often replaced with a word.
ALBANY, NY / ACCESS Newswire / October 11, 2026 / Crescent Bioresearch, a supplier of laboratory reagents and compounds, has published an examination of how bacterial endotoxin is reported on certificates of analysis across the industry, where purity and identity are common, a pass or fail endotoxin report included in most, but when attempting to locate a true numerical endotoxin value, there were few to none.
The Regenerative Therapy incident
In 2024, a group of investigators reported in Regenerative Therapy that the bacterial endotoxin test in their cell-culture quality control had failed. The supplement came without a certificate of analysis stating the numerical endotoxin value and ultimately failed quality control, highlighting the significance of a numerical value within an endotoxin report.
The investigators set their own acceptance criterion: less than 1.0 EU/mL in the culture supernatant. Their resolution was not a new protocol, it was a new supplier whose certificate reported the endotoxin value, so that the concentration in the finished medium could be calculated before the material ever touched a culture. The case is small, carefully reported and entirely ordinary, which makes it of great concern. It describes a significant gap found within many endotoxin reports across the laboratory compound industry, that in turn, have caused massive disruption across scientific literature as a whole.
What a certificate is meant to answer
A certificate of analysis for a laboratory compound answers three separate questions, each by a method suited to a separate metric. Apart from the chemical supply industry, the United States Pharmacopeia keeps those methods under their own general chapters. Infrared spectroscopic identification, under USP <197A>, answers whether the material is the compound named on the label. Chromatography, under USP <621>, answers how much of the material is that compound. The Bacterial Endotoxins Test, under USP <85>, answers what endotoxin burden the material carries.
Identity, purity and endotoxin measure three unrelated ways a reagent can fail. The first two reach a certificate as data, an infrared spectrum matched against a reference and a purity percentage taken from a chromatogram. The third mostly arrives as a pass/fail metric without a numerical value attached. A research entity can read 99.8% and know what it means. It cannot read "pass" and know anything, because the number the verdict was supposedly measured against is not on the page.
A word where the number should be
"The term 'pass/fail' carries no defined meaning on a certificate when the threshold it refers to goes unstated," the company said. "Pass and fail are two words standing in for a number that was never published. Without that number, there is nothing to evaluate."
Many laboratory compound suppliers carry out numerous forms of testing. Yet few of the endotoxin reports they publish include the true numerical value; most carry a pass/fail notation that has no weight when the endotoxin burden is unknown and the threshold arrives unstated. Where an endotoxin result is offered as a verdict with no number attached, the result itself is rendered null.
Why the number is often missing
Third-party laboratories that report a numerical endotoxin value take substantially longer to return it to the suppliers who send samples in. A market requiring laboratory compounds and reagents to be available quickly will often reward the laboratory that returns a verdict in days over the one that returns a quantified value in weeks.
"The true numerical endotoxin value is absent from most certificates published today, and when suppliers are asked about that absence, a clear answer rarely follows," the company said. "The research entities that buy these compounds are the same entities who conduct studies that decide whether those compounds advance toward pharmaceutical development. A medication on a pharmacy shelf was once a laboratory compound, and it advanced only on the strength of the data behind it."
Who determines the threshold
USP <85> is the United States Pharmacopeia's compendial chapter for the Bacterial Endotoxins Test. Apart from the laboratory compound sector, in pharmaceutical manufacturing it is applied by calculating an endotoxin limit specific to each drug product; the chapter itself does not publish one number for every material. A pass/fail result on a pharmaceutical certificate carries meaning because that product-specific limit sits behind it.
Laboratory reagents have no such limit behind them, and the reason is structural. The federal hazard-communication standard requires a chemical supplier to furnish a safety data sheet; it does not require the supplier to test for purity or endotoxin. The good-laboratory-practice regulations place responsibility for characterizing a test article, including its purity, on the study sponsor or testing facility, not on the supplier. The research-and-development provisions of the Toxic Substances Control Act place a substance used in research under the supervision of a technically qualified individual at the research site. No federal mandate requires a supplier to test a compound sold for laboratory use for bacterial endotoxin, and none sets a number the supplier must meet.
The consequence is the one the Regenerative Therapy investigators lived through. A research entity must devise its own acceptance criterion to be able to determine whether the material it will conduct studies with is acceptable for its model. When cell-culture work proceeds with material that has not been properly ruled out for bacterial endotoxins, the data cannot be fully attributed to a mechanism of the compound, and the reported outcome is weakened at its base.
In a cell-culture study, bacterial endotoxin is one of the key triggers of an immune response. When a scientist observes physical or cellular changes under a microscope, or detects biochemical signals released into the surrounding culture medium, that can indicate that the material they were working with triggered an immune reaction, and bacterial endotoxin is a common culprit.
The three figures of an endotoxin report
A laboratory testing for endotoxins sets an assay sensitivity, which then determines the lowest concentration its method can detect, and that sensitivity is often mistaken for the numerical endotoxin value. The assay sensitivity, commonly 0.05 to 0.25 EU/mL, sets a calibration for compound detection based on a desired sensitivity. A maximum threshold is set, used to rule out a pass or fail. And a numerical endotoxin value (EU/mL) , being the figure that is then weighed against the maximum threshold. If you read an endotoxin report that only shows a pass metric with an assay sensitivity of .05, it raises questions on how the aforementioned metric was concluded with no numerical endotoxin value EU/mL.
"Unverified compounds and incomplete testing reports remain common throughout the laboratory compound industry. It is crucial for research entities to request that their suppliers provide an endotoxin value, and where a supplier cannot provide one, to question where its pass/fail metric came from," Crescent Bioresearch said. "The research entities that publish scientific literature are writing both the present and future of science. That record holds only as long as a strict standard is kept for the material it was built on."
METHODOLOGY
This examination is based on the following sources.
Uehara, K., Oshiro, E., Ochiai, A., Takagi, R., Yamato, M., & Kato, A. (2024). Lessons learned from contamination with endotoxin originated from the supplement in the cell culture medium. Regenerative Therapy, 27, 230-233. https://doi.org/10.1016/j.reth.2024.03.022
United States Pharmacopeial Convention. General Chapter <85> Bacterial Endotoxins Test; General Chapter <197A> Spectroscopic Identification Tests; General Chapter <621> Chromatography. United States Pharmacopeia and National Formulary.
Hazard Communication, 29 C.F.R. § 1910.1200.
Good Laboratory Practice for Nonclinical Laboratory Studies, Test and Control Article Characterization, 21 C.F.R. § 58.105.
Research and Development Exemption, 40 C.F.R. § 720.36.
Market observations are drawn from a review of publicly posted certificates of analysis and third-party test findings within the laboratory compound and reagent sector.
FREQUENTLY ASKED QUESTIONS
What happened in the Regenerative Therapy case?
Investigators manufacturing cell sheets traced a failed bacterial endotoxin test in their culture supernatant to a purchased medium supplement that came without a certificate stating its endotoxin value. They resolved it by moving to a supplier whose certificate reported the value.
What is bacterial endotoxin?
A lipopolysaccharide from the outer membrane of Gram-negative bacteria. It is released when the bacteria die and survives the filtration and sterilization steps that remove the bacteria themselves. In a cell-culture model, the cells' response to it can be mistaken for a response to the compound under study or an immune response within the cell culture.
Why can a supplier's pass or fail result not substitute for the number?
For a laboratory compound, a pass/fail result can only be derived from a numerical value that is then compared against a threshold acceptance criterion. A pass or fail metric presented without the numerical value cannot be evaluated by the research entity.
ABOUT CRESCENT BIORESEARCH
Crescent Bioresearch is a supplier of laboratory compounds and reagents based in Albany, New York, founded around a framework of critical assessment. It works with research entities nationwide in pursuit of advancing and maintaining the integrity of scientific research. Learn more at https://crescentbioresearch.com/about and view the Crescent Discovery Series to dive into the latest scientific breakthroughs at https://crescentdiscoveryseries.com.
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SOURCE: Crescent Bioresearch