“None detected” is only as good as the limit written next to it. Without that limit, it is not an answer yet.

Three phrases turn up on supplier test reports and certificates of analysis (CoAs) and look like answers. Each one answers a narrower question than the one you asked. This article takes them one at a time, for quality, regulatory and purchasing teams at cosmetics, supplement and food companies: what each phrase says, what to ask for instead, and how to read a report so the gap shows before it reaches a claim.

What “none detected” means on a test report

Every analytical method has a floor, a level below which it cannot tell a small amount of something from nothing. FDA’s guidelines for validating chemical methods in food, feed and cosmetics define the limit of detection (LOD) as “the minimum amount or concentration of analyte that can be reliably distinguished from zero.” The limit of quantitation (LOQ) sits above it, at the lowest amount that “can be quantified with acceptable precision.”

So “none detected” means the lab found nothing at or above its method’s limit. It does not mean the sample contains none. FDA’s own pesticide monitoring shows the two floors at work: residues found above the LOD but below the LOQ are designated “trace” values.

The limit belongs to the method as the lab ran it, not to your material. FDA’s guidelines say the method detection limit depends on “sensitivity, instrumental noise, blank variability, sample matrix variability, and dilution factor.” Change the instrument, the sample type or the dilution, and the floor can move.

That is why the limit decides what the result can support. If your specification or label claim needs an amount below a stated level, and the method’s limit sits above that level, “none detected” is consistent with a sample that fails. If no limit is printed at all, the true amount could sit anywhere below a number you do not know.

US supplement rules already ask for more than the word. Under 21 CFR 111.75, where a supplement maker relies on a supplier’s certificate of analysis instead of testing a component itself, one condition is that the certificate “includes a description of the test or examination method(s) used, limits of the test or examinations, and actual results of the tests or examinations.” The rule binds supplement makers, but its three items are what any reader needs to judge a result: how it was measured, against what limit, and what was found.

“Gluten below 20 ppm” answers a question about gluten

Twenty parts per million is the US food labeling line for “gluten-free.” Under 21 CFR 101.91, any unavoidable gluten in a food that carries the claim must be “below 20 ppm.” FDA explains that this level “is the lowest that can be reliably detected in foods using scientifically validated analytical methods,” and that other countries and international bodies use the same criteria. The line itself sits at what the methods can reliably see.

The rule defines gluten as “the proteins that naturally occur in a gluten-containing grain,” meaning wheat, rye, barley and their crossbred hybrids. A gluten result measures that protein. It does not say which grain an ingredient came from.

The rule is written around that gap. It allows an ingredient “derived from a gluten-containing grain and that has been processed to remove gluten (e.g., wheat starch)” in a gluten-free food, provided the food stays below 20 ppm. A food that declares wheat and also claims gluten-free must explain it beside the ingredient list: “The wheat has been processed to allow this food to meet the Food and Drug Administration (FDA) requirements for gluten-free foods.” One product can be gluten-free and contain wheat.

Wheat is one of the nine major food allergens under US law, and its label declaration names the source, as in “flour (wheat).” The allergen labeling law reaches dietary supplements as well as packaged foods, and FDA states that it “has not established a threshold level for any allergens.” No ppm figure settles a wheat question. Whether a new ingredient comes from wheat is answered by the supplier’s statement of origin for each component, not by a gluten assay.

Both are food rules, and FDA’s allergen labeling enforcement does not extend to cosmetics. A cosmetics buyer may still meet the 20 ppm figure on an ingredient specification, and there too it answers only the gluten question. The Elara page works through this case, a wheat-derived carrier reported below 20 ppm gluten, among its illustrative examples.

“Detected” on an organic lot makes no call by itself

The third phrase runs the other way. A report says a residue of a prohibited pesticide was detected on an organic lot, and it reads like a failure.

The National Organic Program rule that takes a product out of organic sale on a test result reads a number. Under 7 CFR 205.671, when residue testing detects prohibited substances “at levels that are greater than 5 percent of the Environmental Protection Agency’s tolerance for the specific residue detected or unavoidable residual environmental contamination,” the product “must not be sold, labeled, or represented as organically produced.” A tolerance, in FDA’s words, is “the EPA-established maximum residue level of a specific pesticide chemical that is permitted in or on a human or animal food in the United States.”

A detection still matters. The same section lets the certifying agent or program officials investigate its cause. But the exclusion on a test result turns on the amount read against that yardstick, so the word makes no call and the number does.

How to read a supplier document so the gap is caught

One habit catches all three. Write down the question your claim needs answered, find the limit the result was read against, and only then read the result.

The same reading works on any supplier document, line by line:

• Write the question first. “Is lead below our specification?” and “Was lead found?” need different evidence.
• For every “none detected,” “not detected” or “ND,” find the method and its limit, which kind of limit it is, and its units.
• Compare that limit with the level your claim or specification needs. A limit above your level cannot support your claim.
• Check that what was measured matches what you asked. Gluten is not wheat, and one metal does not answer for the rest.
• Read a verdict such as “complies” or “passes” as a limit met, not a result found, and ask for the number.
• Where something was detected, read the amount against the yardstick the rule uses, not the word on the report.
• If any of these is missing, ask the supplier for it before the document is filed.

Chemists read the limit before the result. It is the habit a chemistry lab trains into you. An automation built by someone who reads that way does the same: it treats “none detected” with no limit as a missing number and asks for it, instead of filing the word as the answer. What the number means for your claim stays a person’s call.