# What “None Detected” Means in Microplastics Testing

> "None detected" ≠ zero microplastics. The Wellness Quality Institute explains detection limits & how to read your lab report accurately.

**Published:** 2026-10-18 | **Updated:** 2026-10-31 | **Author:** mihir
**URL:** https://www.wellnessqualityinstitute.com/articles/none-detected-microplastics-testing-meaning
**Type:** post

**Categories:** Water Quality

![What “None Detected” Means in Microplastics Testing](https://wellnessquality.sites.aigrowthagent.co/wp-content/uploads/sites/93/2026/10/1792234135579-de2bdb938f54-1024x572.webp)

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## Content

*Written by: Scott Steveson, Specialist, Wellness Quality Institute*

## Key Takeaways

- “None detected” means the lab did not find target plastic particles above its detection limit for the method, size range, and polymers tested. The phrase does not mean the sample contains no plastic.
- Validated methods like SWB-MP1-rev1 and SWB-MP2-rev1 reliably measure particles only above 20 µm or 50 µm. Smaller particles sit outside what these tests can see.
- A “none detected” result is bounded by the analytical method, detection limits, polymer panel, blanks, sample size, accreditation, and data recency. Each field shapes how much confidence you can place in the finding.
- Three gaps in every test let plastic particles coexist with a “none detected” result: size limits, polymer panel limits, and lot-to-lot variability.
- The Wellness Quality Institute reviews existing lab data against its Plastic-Free Pathway Verification standard so companies can turn bounded results into clear, defensible claims.

[Learn How The Wellness Quality Institute Can Verify Your Microplastics Data.](https://www.wellnessqualityinstitute.com/?utm_term=none-detected-microplastics-testing-meaning&utm_campaign=ai_growth_agent)

## How “None Detected,” “None Present,” And “Zero Microplastics” Differ

These three phrases sound similar, yet they describe very different things.

- **None Detected**. The lab did not find target polymer particles above the method’s detection floor, within the tested size range and polymer list, in the sample analyzed.
- **None Present**. This phrase claims that no plastic exists in the sample at any size, in any polymer, at any concentration. No current analytical method can support that statement.
- **Zero Microplastics**. This phrase is a marketing absolute. A lab report cannot support it, because detection can show presence but cannot prove absence across every size, polymer type, and production lot.

Only “none detected” describes what a laboratory actually did. The other two describe something no laboratory can currently do.

## How Particle Size Limits What Your Test Can See

The particle-size range a method can truly measure sets the firmest boundary around any “none detected” result. Two analytical methods developed by the California State Water Board set the most stringent publicly available reference point for this testing. The table below shows where each method’s validated range begins and highlights the size band neither method covers, which is the boundary that turns “none detected” into a limited claim rather than a guarantee.

![Colorful plastic fragments in water inside a laboratory petri dish.](https://cdn.aigrowthmarketer.co/1784829410323-fb401fc7b1e4.webp)**Microplastics are particles smaller than five millimeters. Current methods can count and identify them at the upper end of that range, but reliable measurement falls away as particles get smaller — a limit that shapes every honest claim.**

| Method | Technique | Validated Particle-Size Range |
| --- | --- | --- |
| [SWB-MP1-rev1](https://www.waterboards.ca.gov/drinking_water/certlic/drinkingwater/microplastics.html) | Infrared Spectroscopy | >50 µm through 5,000 µm |
| [SWB-MP2-rev1](https://www.waterboards.ca.gov/drinking_water/certlic/drinkingwater/microplastics.html) | Raman Spectroscopy | >20 µm through 5,000 µm |
| Unvalidated Fraction | Not validated under either method | 1–20 µm |

The 1–20 µm fraction is not validated under either California method. That gap is why “none detected” is a bounded statement rather than a guarantee: a method starting at 50 µm cannot see anything smaller, so particles below that threshold are invisible to it. California’s own drinking-water definition reaches down to 1 nanometer, thousands of times smaller than the best validated methods can measure, which widens the gap further. That distance between the regulatory definition and what instruments can actually detect explains why no laboratory can certify a product plastic-free.

![Fragments of plastic suspended in blue water below the surface.](https://cdn.aigrowthmarketer.co/1784829388732-c6255482b477.webp)**Plastic doesn’t disappear — it fragments. These secondary microplastics are the breakdown products of everyday objects, and independent research now detects them across the water supply. Detection, though, establishes presence, not absence.**

ISO 16094-2:2025, the international standard for vibrational spectroscopy in low-suspended-solids waters, [states a nominal particle-size range of 1 µm to 5,000 µm](https://glstd.com/sist-en-iso-16094-2-2025). This looks broader on paper than the California methods. In practice, a laboratory’s validated reporting range is often narrower than a standard’s nominal scope, and ISO 16094-2:2025 does not automatically substitute for the California SWB methods. The method named on your report, and its validated range, define what “none detected” actually covers.

For a side-by-side comparison of analytical techniques and what each one proves, see [Microplastics Analysis Techniques: What Each Method Proves](https://www.wellnessqualityinstitute.com/articles/microplastics-analysis-techniques-comparison/?utm_term=none-detected-microplastics-testing-meaning&utm_campaign=ai_growth_agent).

## What To Check Before Trusting A “None Detected” Result

A lab report contains many fields, and “none detected” in the summary row only matters when you understand the details behind it. Use this checklist on the report in front of you.

1. **The analytical method and its validated particle-size range.** Check whether the method uses infrared or Raman spectroscopy and confirm the lower size floor. A method starting at 50 µm cannot speak to anything smaller, so a non-detect is a method-specific statement about evidence, not a universal statement of absence.
2. **The limit of detection and reporting limits.** The limit of detection (LOD) is the lowest concentration the method can reliably distinguish from background noise, and the reporting limit (sometimes called the limit of quantitation, or LOQ) is the level above which a number becomes usable. A “none detected” total can coexist with particles counted in specific size bins that fall below the LOQ, so both thresholds matter. If the reporting limit sits too high relative to the benchmark you care about, the test was not sensitive enough to answer your question.
3. **The polymer panel tested.** A result covers only the polymers the method was asked to screen. The minimum defensible panel for drinking-water microplastics typically includes polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), polystyrene (PS), polyvinyl chloride (PVC), polyamide (PA), polycarbonate (PC), and polymethyl methacrylate (PMMA). A report that screened only a subset says nothing about the polymers left out.
4. **Blanks and contamination controls.** Procedural blanks are samples of clean water processed through the same steps as the real samples. They help separate genuine detections from contamination introduced during handling. [Blank results must be read alongside any “none detected” finding to judge whether contamination or method limits shaped the result](https://pmc.ncbi.nlm.nih.gov/articles/PMC13520088). A report without blank data leaves a key question unanswered.
5. **Sample size and number of production lots tested.** One aliquot from one production lot does not represent the entire product line. [Replicate sampling addresses spatial and temporal variability](https://link.springer.com/article/10.1007/s11270-026-09684-x). A single sample may miss meaningful differences across batches.
6. **Chain of custody and laboratory accreditation.** The laboratory’s accreditation should cover the specific method and matrix, not just general testing. Preferred accreditation for the California SWB methods is California ELAP (Environmental Laboratory Accreditation Program). [ISO/IEC 17025:2017](https://www.iso.org/standard/66912.html) accreditation with the method and matrix explicitly within scope also works. Accreditation that does not name the method leaves a gap.
7. **Data recency.** A dataset describes the production period it came from, not today’s production. Lot-to-lot variability is real, and a result from a prior period does not guarantee the current one.

Three of these fields, size range, polymer panel, and lot coverage, deserve special attention because each one can hide particles behind a “none detected” result.

## Why “None Detected” Can Coexist With Particles Present

Three structural gaps explain how a “none detected” result can sit alongside plastic particles in the same product or system.

- **Particle-size limits.** Particles below the method’s validated floor are invisible to that method. A method starting at 50 µm cannot detect a 30 µm particle, a 5 µm particle, or a nanoplastic. [When microplastic size falls below 50 µm, accurate quantification becomes challenging, and the transition to nanoplastics creates a major methodological bottleneck](https://link.springer.com/article/10.1007/s10311-026-01902-6).
- **Polymer panel limits.** Polymers outside the tested panel never appear in the report. The breadth of the result matches the list of polymers the laboratory was asked to identify.
- **Lot-to-lot variability.** A clean result on one production lot says nothing about the next lot without additional sampling. [Differences in sampling protocols, particle-size cutoffs, and analytical sensitivity limit cross-study comparison](https://pmc.ncbi.nlm.nih.gov/articles/PMC13363690), and the same logic applies across production runs.

Consider a worked example. A report reading “none detected” from an infrared method starting at 50 µm, run on a single production lot, means the lab did not find target polymer particles above 50 µm, for the polymers screened, in that lot. The 1–20 µm fraction was not measured. Polymers outside the panel were not screened. Other lots were not tested. The same logic applies when people compare water sources, where a single clean sample is often read as a clean source.

## The Measurement Gap And Why Absolute Claims Fail

The size gap described earlier is the reason absolute claims fail. The California drinking-water microplastics definition reaches down to 1 nanometer, while the best validated methods begin at 20 or 50 micrometers. One micrometer equals 1,000 nanometers, so validated methods start thousands of times above the lower boundary of the regulatory definition. The 1–20 µm fraction sits outside the validated reporting range of both methods, and everything below 1 µm, the nanoplastic range, remains beyond reliable commercial measurement.

[A 2026 PRISMA-guided review in *Molecules* concluded that nanoplastic detection in drinking water remains analytically immature, with no single method able to resolve size, shape, polymer identity, and mass concentration at once](https://mdpi.com/1420-3049/31/15/2675). Regulators and standards bodies echo this view. [The U.S. EPA has said no standalone method can characterize the full diversity of micro- and nanoplastic particles across environmental matrices](https://mdpi.com/1420-3049/31/15/2675), and [NIST has noted that current methods generally lack the sensitivity needed for nanoplastics](https://mdpi.com/1420-3049/31/15/2675).

This measurement gap prevents any laboratory from certifying a product plastic-free. An honest claim stays bounded by the reviewed scope of the test rather than by the product itself.

## Where The Wellness Quality Institute Fits In Your Claim Strategy

The Wellness Quality Institute is an independent verification body that reviews a company’s existing third-party laboratory data, testing methodology, product scope, and supporting controls against its Plastic-Free Pathway Verification standard, WQI-CS-01. This standard aligns with the California State Water Board’s drinking-water microplastics reference framework. The Wellness Quality Institute does not run laboratory tests and does not certify that any product is free of plastic.

![Scientists in white coats working with samples and microscopes in a laboratory.](https://cdn.aigrowthmarketer.co/1784829434095-0fc8fbcf29fa.webp)**Only a small number of laboratories can genuinely test for microplastics, and capability varies by instrument and method. WQI reviews a company’s existing third-party laboratory data against a defined standard — it does not run the tests itself.**

Many companies already hold strong laboratory data yet lack a trusted, independent way to use it. A lab report alone rarely functions as a defensible market claim. Self-reported results carry less weight than independently reviewed data, and without that review, even rigorous data often reads as marketing. The Wellness Quality Institute evaluates whether the method suited the material tested, whether reporting limits were adequate, whether blanks and controls were run, and what claim the data can actually support. For a detailed look at independent review, see [Microplastics Lab Results: What The Data Actually Means](https://www.wellnessqualityinstitute.com/articles/independent-review-lab-results-microplastics/?utm_term=none-detected-microplastics-testing-meaning&utm_campaign=ai_growth_agent).

The Wellness Quality Institute review process produces one of two outcomes. A **Standard Met** outcome carries a verification decision, a scope-locked license to use the WQI mark, a public registry listing, and approved claim language. A **Standard Not Met** outcome remains private. It is never described as a failed product and can reflect insufficient data or an unsupported method rather than any conclusion about the product. Companies can resubmit with updated information, so participation carries no public downside risk.

A single assessment fee covers review, verification decision, and registry listing. There is no separate mark-license or registry fee. Independent laboratory testing is arranged and billed separately by a qualified independent laboratory.

>
*WQI Plastic-Free Pathway Verification does not certify that a product contains zero plastic, microplastics, or nanoplastics. It shows that the company is on a verified pathway toward plastic-free standards. Verification applies only to the reviewed products, submitted datasets, tested ranges, polymer panels, production or sampling periods, and supporting controls. WQI verification is not a California approval, government certification, or health or safety certification.*

[See Whether Your Existing Lab Data Can Support A Verified Claim.](https://www.wellnessqualityinstitute.com/?utm_term=none-detected-microplastics-testing-meaning&utm_campaign=ai_growth_agent)

The questions below cover the points readers most often ask after reviewing a microplastics report.

## Frequently Asked Questions

### What Does “None Detected” Mean In Microplastics Testing?

“None detected” means no target polymer particles were found above the laboratory’s limit of detection. That limit is the lowest concentration the method can reliably distinguish from background. The finding applies only to the method used, the size range tested, and the polymers screened. Particles below the method’s size floor, polymers outside the tested panel, and production lots that were not sampled all sit outside what the result can address.

### Does “None Detected” Mean Zero Microplastics?

“Zero microplastics” is an absolute claim that no lab report can support. Detection can establish presence, because finding a particle requires only one confirmed identification. Proving absence would require certainty about everything the method cannot see, including particles below the detection floor, polymers outside the tested panel, and production lots that were not sampled. Because no method covers every size, polymer, and lot, “zero microplastics” remains beyond what laboratories can claim. A result of “none detected” is a bounded analytical finding rather than a guarantee of zero.

### What Is A Microplastics Detection Limit?

The limit of detection (LOD) is the lowest concentration at which the method can reliably distinguish a target substance from background noise. At this level, presence can be established even if the exact concentration remains uncertain. Above the LOD but below the limit of quantitation (LOQ), a substance may be detected but not measured with acceptable precision. Above the LOQ, the number becomes usable. A “none detected” result only carries weight in light of these thresholds. If the reporting limit sits too high relative to the benchmark you care about, the test was not sensitive enough to answer your question. Detection limits vary by method, matrix, laboratory, and analytical conditions.

### Why Is The 1–20 µm Fraction Not Validated?

Neither of the California State Water Board’s published drinking-water microplastics methods validates reporting below 20 µm for Raman (SWB-MP2-rev1) or 50 µm for infrared (SWB-MP1-rev1). The 1–20 µm fraction therefore falls outside the validated reporting range of both methods. Infrared spectroscopy is diffraction-limited and most reliable above roughly 10–20 µm. Raman spectroscopy can reach lower sizes but requires longer per-particle acquisition times and is more vulnerable to interference. As a result, a meaningful portion of the microplastic size range defined by California’s regulatory definition, which reaches down to 1 nanometer, cannot yet be reliably measured by validated commercial methods.

### What Should I Check On A Microplastics Lab Report?

Seven fields determine what a “none detected” result actually covers:

1. The analytical method and its validated particle-size range.
2. The limit of detection and reporting limits.
3. The polymer panel tested.
4. Blanks and contamination controls.
5. Sample size and number of production lots tested.
6. Chain of custody and laboratory accreditation.
7. Data recency.

Each of these fields shapes how far you can safely generalize a single report.

### Can A Lab Report Prove A Product Is Plastic-Free?

A lab report cannot prove that a product is plastic-free. Detection can establish presence but cannot establish absence across every size, polymer, and lot. As covered earlier, the regulatory definition reaches to 1 nanometer while validated methods begin at 20 or 50 micrometers, so the 1–20 µm band and the nanoplastic range fall outside what a report can measure. A lab report can show that no target polymer particles were found above the method’s floor, for the polymers screened, in the lots tested. It cannot show that no plastic is present anywhere in the product or system.

## Conclusion: “None Detected” Describes The Test, Not The Whole Product

“None detected” describes what a specific method, at a specific detection floor, looking for specific polymers, found in a specific sample from a specific production lot. The phrase does not describe the product as a whole and does not prove absence. The three-way distinction among none detected, none present, and zero microplastics is the key point to remember from any lab report. Only the first reflects what a laboratory can currently claim.

For deeper diligence, primary sources include the [California State Water Board’s SWB-MP1-rev1 and SWB-MP2-rev1 standard operating procedures](https://www.waterboards.ca.gov/drinking_water/certlic/drinkingwater/microplastics.html), [ISO/IEC 17025:2017](https://www.iso.org/standard/66912.html), and the [WHO report *Microplastics In Drinking-Water* (2019)](https://www.who.int/publications/i/item/9789241516198). The peer-reviewed literature, including [Mason, Welch, and Neratko (2018) in *Frontiers In Chemistry*](https://www.frontiersin.org/journals/chemistry/articles/10.3389/fchem.2018.00407/full), shows why a single “none detected” result cannot be generalized to a product line, a supplier, or a water system.

[Talk To The Wellness Quality Institute About Plastic-Free Pathway Verification.](https://www.wellnessqualityinstitute.com/?utm_term=none-detected-microplastics-testing-meaning&utm_campaign=ai_growth_agent)

## Read Next

- [What “None Detected” Really Means in Microplastics Testing](https://www.wellnessqualityinstitute.com/articles/none-detected-microplastics-meaning/?utm_term=none-detected-microplastics-testing-meaning&utm_campaign=ai_growth_agent)
- [Microplastics Detection Floors: What Lab Results Really Mean](https://www.wellnessqualityinstitute.com/articles/detection-floor-microplastics-analysis/?utm_term=none-detected-microplastics-testing-meaning&utm_campaign=ai_growth_agent)
- [Microplastics Lab Results: What the Data Actually Means](https://www.wellnessqualityinstitute.com/articles/independent-review-lab-results-microplastics/?utm_term=none-detected-microplastics-testing-meaning&utm_campaign=ai_growth_agent)
- [How To Know If Microplastics Lab Results Are Trustworthy](https://www.wellnessqualityinstitute.com/articles/microplastics-testing-verification-lab-results/?utm_term=none-detected-microplastics-testing-meaning&utm_campaign=ai_growth_agent)
- [Microplastics Testing Limits and How to Judge the Evidence](https://www.wellnessqualityinstitute.com/articles/water-quality-month-microplastics/?utm_term=none-detected-microplastics-testing-meaning&utm_campaign=ai_growth_agent)

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## Citations

- [Nanoplastic Detection Validation: Gaps, Standards & Claims](https://www.wellnessqualityinstitute.com/articles/nanoplastics-detection-methods-validation)
- [Microplastics Standards Compliance: Rules, Status & Evidence](https://www.wellnessqualityinstitute.com/articles/california-microplastics-compliance-rules)
- [Microplastics in Bottled Water: 2024 PNAS Study Findings](https://www.wellnessqualityinstitute.com/articles/microplastics-bottled-water-study)
- [Microplastics vs. Nanoplastics: What You Need To Know](https://www.wellnessqualityinstitute.com/articles/nanoplastics-vs-microplastics)
- [Microplastics in Bottled Water: Which Part Is Responsible](https://www.wellnessqualityinstitute.com/articles/microplastics-sources-bottled-water)

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