Friday, 16 October 2026 11:55 AM
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A pass or fail metric is the comparison of a measured endotoxin value against a threshold. Where neither figure is printed, the metric carries no weight, and the research entity is left to accept a word in place of a measurement.
ALBANY, NY / ACCESS Newswire / October 16, 2026 / Crescent Bioresearch, a supplier of laboratory compounds, has published an examination of the pass/fail metric as it appears on endotoxin certificates across the laboratory supply industry. The numerical endotoxin value and the endotoxin threshold are routinely absent from the certificate of analysis. The examination sets out what the metric requires in order to have merit, what the certificates in circulation actually provide, and what a research entity is left holding when the two do not match.
The missing endotoxin number
Within the laboratory supply industry, there are few to no endotoxin reports publishing the numerical value, and most carry a pass/fail metric or no endotoxin result at all. A pass/fail metric has no merit if the endotoxin burden is unknown and its threshold arrives unstated. If the endotoxin result is provided as a pass/fail result unassociated with a numerical value, the aforementioned metric itself becomes null.
The absence is consistent across the industry. In a review of 25 publicly posted certificates of analysis conducted by the company on Oct. 1, 2026, three reported a measured endotoxin value, three reported a detection limit, eight reported a pass/fail result with no measured value, and 11 carried no endotoxin result at all. Twenty-two of the 25 certificates therefore gave a research entity no measured endotoxin value.
What a pass/fail metric requires
A pass/fail result is derived from two figures: the amount of endotoxin measured in the sample, and the threshold that amount was compared against. No threshold exists for a laboratory compound unless one is set, and the party that sets it, whether the laboratory or the client that commissioned the test, is accountable for stating it. A laboratory that would rather not set a threshold may report the numerical endotoxin value alone and leave the determination to the research entity. A laboratory that reports a pass or a fail has made the determination itself, and in doing so has taken on the obligation to provide both the threshold it applied and the numerical value it applied the threshold to.
The United States Pharmacopeia holds the same position in the chapter every endotoxin certificate cites. USP General Chapter 85, Bacterial Endotoxins Test, points toward an LAL endotoxin limit test as a test "used when a monograph contains a requirement for endotoxin limits," and a preparation complies "when a negative result is found" at a dilution calculated from that limit. The chapter further states that in its quantitative gel-clot assay, where no reaction is observed at any dilution, the laboratory reports the endotoxin concentration as less than the lysate sensitivity multiplied by the dilution tested.
The assay sensitivity is a calibration, not a result
The one figure that routinely accompanies the pass/fail metric is the assay sensitivity, commonly set between 0.03 and 0.25 EU/mL. A laboratory that tests for an endotoxin load selects a lysate whose labeled sensitivity determines the lowest concentration the method can detect, and that sensitivity is often mistaken for the numerical endotoxin value. USP Chapter 85 defines the labeled lysate sensitivity as "the minimum concentration of endotoxin required to cause the lysate to clot under standard conditions," which is to say a property of the lysate, confirmed against a reference standard before the sample is tested and identical for every sample tested. The lower the figure, the smaller the amount of endotoxin the lysate is able to detect. If the certificate of analysis shows only the sensitivity calibration along with a pass or fail result, the certificate has not provided an endotoxin value.
The sensitivity is also the reason a laboratory is never without a number to report. A negative result in the chapter's gel-clot assay is reported as less than the sensitivity times the dilution, which is a figure, and a laboratory that answers a question about the endotoxin value by stating that endotoxin was not present has substituted a description for a figure it already holds: the sensitivity and the dilution it tested at.
A plain comparison
A student sits an examination on which 70 is the mark required to pass. The paper comes back with a score of 68, and the student can see the score, can see the line, and can see that the shortfall was two points. A teacher who disagrees can check the same two figures and arrive at the same answer. Now suppose the paper came back with the single word "fail" written across it: no score, no pass mark, no questions marked right or wrong. The student would not know what failed, would not know by how much, and would have no way of knowing whether anyone had read the paper at all prior to providing a grade. No school would accept that as a grade, and no research entity should accept that as a result.
An endotoxin certificate that states "pass" with no measured value and no threshold is that paper. The research entity cannot determine whether the sample came in well beneath the threshold or just beneath it, cannot determine what the threshold was, and cannot determine whether a measurement was made at all. A grade without a score is not accepted anywhere else, and there is no reason for the laboratory supply industry to accept it on a certificate.
What Crescent Bioresearch encountered
Crescent Bioresearch has worked with more than one laboratory within the laboratory supply industry. Before settling on the laboratory that currently tests its lots, the company received endotoxin certificates from another laboratory and was dissatisfied with what they provided. Each certificate carried the word "Pass" on two replicate lines, an assay sensitivity of 0.05 EU/mL or less, no numerical threshold for either line, and no numerical endotoxin value in any unit. When asked for the missing numerical value, that laboratory did not provide one, and deflected the issue by pointing at endotoxin load as a whole instead of a number, either present or not present. The company moved its testing to a laboratory whose certificates print all four parameters. The instance calls for closer scrutiny of the many publicly available reports that carry only a pass or fail metric.
"The true numerical endotoxin value is absent from the majority of certificates being published, and when the absence is raised with laboratories and suppliers alike, a clear explanation rarely follows," the company said. "A laboratory that has performed the test holds a figure, because the test is defined by one. A laboratory that cannot provide that figure when asked has left the research entity with no means of distinguishing a measurement from an assertion."
What the number decides at the bench
The consequence of an unreported value is documented in the literature. In 2003, the Veterans Affairs Medical Center in Washington, D.C., reported in The Journal of Biological Chemistry on two commercial preparations of recombinant human heat shock protein 70. The two preparations contained the same amount of protein and showed similar enzymatic activity. The supplier sold the first as a low-endotoxin preparation and had not tested the second for endotoxin at all. They greatly differed in endotoxin burden. One carried 1.4 picograms of lipopolysaccharide per microgram of protein, the other 0.2 nanograms per microgram, 140 times as much, and only the second caused mouse macrophages to release tumor necrosis factor alpha. When the endotoxin was removed, the activity was essentially eliminated; when endotoxin was added to the first preparation, the activity appeared. The authors concluded that the activity was entirely due to the contaminating endotoxin.
Protein content and enzymatic activity could not have provided distinction. Only the endotoxin value could signify the difference, and a certificate reading "pass" for either would have left the research entity attributing to the compound an effect that belonged to the contaminant.
Where the pass/fail verdict originates and who determines the threshold
The federal hazard-communication standard requires a chemical supplier to furnish a safety data sheet; it does not require the supplier to test the material for purity or endotoxin. The good-laboratory-practice regulations, which govern nonclinical studies submitted to the FDA, require that each batch of a test article be characterized and documented; they bind the study sponsor and the testing facility, and the supplier is not a party to them. 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 that a research entity must devise its own acceptance criterion and must be able to check a compound against it, and the numerical value is the only form of the result that can be carried across to that criterion.
"Unverified compounds and incomplete testing reports remain common across the laboratory supply industry. It is vital for research entities nationwide to question their suppliers on the numerical endotoxin value and the threshold that any pass/fail metric was issued against," Crescent Bioresearch said. "For the research entities that publish scientific literature, remember that your data shapes the future of science. The people read your literature and take it as fact. They don't read it as data, they read it as answer. The people deserve nothing less than transparency and truth."
METHODOLOGY
This examination is based on USP General Chapter 85, Bacterial Endotoxins Test (labeled lysate sensitivity; Gel-Clot Limit Test and its interpretation; the reporting of a negative result as less than the sensitivity times the dilution; maximum valid dilution; endotoxin limit K/M); FDA, Guidance for Industry, Pyrogen and Endotoxins Testing: Questions and Answers, June 2012, https://www.fda.gov/media/83477/download; Booth CM, "Validation Strategies for Gel-Clot Bacterial Endotoxin Testing," American Pharmaceutical Review, Endotoxin Detection supplement, August 2021; Gao B, Tsan MF, "Endotoxin contamination in recombinant human heat shock protein 70 (Hsp70) preparation is responsible for the induction of tumor necrosis factor alpha release by murine macrophages," The Journal of Biological Chemistry 2003;278(1):174-179, https://doi.org/10.1074/jbc.M208742200; the federal hazard-communication standard at 29 CFR 1910.1200 and the good-laboratory-practice provisions at 21 CFR 58.105; and the endotoxin certificates and correspondence the company received from a third-party laboratory in June 2026. The company's review of 25 publicly posted certificates of analysis was conducted Oct. 1, 2026.
FREQUENTLY ASKED QUESTIONS
What does a pass/fail metric require in order to be evaluated?
The numerical endotoxin value that was measured and the threshold it was compared against. A pass or a fail printed without either figure cannot be evaluated by the research entity.
What is the difference between the assay sensitivity and the endotoxin value?
The assay sensitivity is the lowest concentration the lysate can detect. It describes the method and is the same for every sample run with that lysate. The endotoxin value is what the laboratory measured in the specific sample.
Does "no endotoxin detected" mean the sample contained none?
It means none was found above the sensitivity of the lysate at the dilution tested. Under USP Chapter 85's gel-clot assay, that result is reported as less than a stated figure, and the figure belongs on the certificate in order to assess detection.
Who determines the numerical threshold for a laboratory compound?
Whoever issues the pass or fail. A laboratory that reports the numerical value alone leaves the criterion to the research entity. A laboratory that reports a pass has set a threshold and is accountable for stating it. Certificates that print the value and the threshold together let the research entity check one against the other.
ABOUT CRESCENT BIORESEARCH
Crescent Bioresearch is a supplier of laboratory compounds and reagents, founded around a framework of critical assessment. It works with research entities nationwide in pursuit of preserving the integrity of scientific research as a whole through its extensive testing and transparency approach. Follow the Crescent Discovery Series to dive into the latest breakthroughs and findings within prominent literature.
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SOURCE: Crescent Bioresearch