# Microplastics Methodology Validation: A Practical Guide

> The Wellness Quality Institute explains how to validate microplastics testing methods for defensible, credible data. Get expert guidance today.

**Published:** 2026-08-14 | **Updated:** 2026-10-31 | **Author:** renatoloureiro
**URL:** https://www.wellnessqualityinstitute.com/articles/microplastics-testing-methodology-validation
**Type:** post

**Categories:** Certification

![Microplastics Methodology Validation: A Practical Guide](https://wellnessquality.sites.aigrowthagent.co/wp-content/uploads/sites/93/2026/08/1786614156845-10c402960cba-1024x572.webp)

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## Content

*Written by: Scott Steveson, Specialist, Wellness Quality Institute | Last updated: October 15, 2026*

Microplastics testing method validation shows that a lab method can reliably find plastic particles, measure how many are present, and control contamination for a specific product type, particle-size range, and list of polymers. It does this through blanks, spike recovery, precision checks, and detection-limit studies.

![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.**

## Key Takeaways For Brands And Labs

- Microplastics testing method validation proves that a method can reliably identify plastic particles, measure them, and control contamination for a specific product type, size range, and polymer list.
- Method validation sets performance for the first time for a defined matrix, size range, and polymer panel. Method verification confirms that an already validated method still performs as expected in a specific lab on specific instruments.
- A complete validation covers eight parameters: specificity, accuracy and recovery, precision, blanks, LOD and LOQ, linearity, matrix effects, and robustness. Each one must be shown for the actual product and conditions being tested.
- Contamination control is a core validation requirement. Labs must run procedural and field blanks with samples and correct results against those blanks so the data can be interpreted and defended.
- The Wellness Quality Institute (WQI) independently reviews laboratory datasets and validation documentation so companies can turn raw lab numbers into defensible market claims through Plastic-Free Pathway Verification.

[Talk to the Wellness Quality Institute about whether your current data can support Plastic-Free Pathway Verification.](https://www.wellnessqualityinstitute.com/?utm_term=microplastics-testing-methodology-validation&utm_campaign=ai_growth_agent)

## How Validation Differs From Verification In Microplastics Testing

Method validation shows for the first time that a method works for a specific product type, particle-size range, and polymer list. Method verification checks that a method that has already been validated still performs as expected in a particular laboratory, on a particular instrument, with a particular analyst.

The distinction matters for commercial claims. A laboratory accredited under [ISO/IEC 17025:2017](https://www.iso.org/standard/66912.html), the international standard for laboratory competence, is not the same as a method validated for your product. Accreditation confirms that a laboratory runs a quality system and has shown competence for a defined scope. Validation confirms that the method itself works for the specific combination of product matrix, particle size, and polymer types you plan to report. A laboratory can be fully accredited and still use a method that was never validated for bottled water, a supplement slurry, or another specific format.

[ISO 24187:2023](https://www.iso.org/standard/80720.html), which gives general principles for microplastics analysis, treats validation as required evidence that a method is suitable. It does not set numerical pass–fail limits. Each laboratory must define its own numerical acceptance criteria in its validation protocol, using reasoning that fits the product and use case.

## Eight Core Parameters Every Microplastics Validation Must Cover

A complete microplastics method validation covers eight parameters. Each one must be demonstrated for the specific product matrix, size range, and polymer panel under review.

![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.**

1. **Specificity** is the method’s ability to confirm that a particle is a target plastic and not a similar-looking material. In practice, this means chemical confirmation by spectroscopy or pyrolysis, not visual inspection alone.
2. **Accuracy / Recovery** describes how much of a known spike the full workflow recovers. The measurement runs from sample collection through every handling step to final detector classification.
3. **Precision** covers repeatability and intermediate precision across replicates, days, and operators. It shows that results stay consistent under normal working conditions.
4. **Blanks** include field and procedural blanks that travel with the sample from collection through analysis. They establish the contamination baseline used to interpret results.
5. **LOD / LOQ** are the detection limit and quantification limit. The LOD is the lowest amount distinguishable from the blank. The LOQ is the lowest amount that can be measured with acceptable accuracy and precision. Both come from the blank distribution in the real sample matrix.
6. **Linearity** is the range over which instrument response tracks particle number or mass. It confirms that the method behaves consistently across the concentration range of interest.
7. **Matrix Effects** describe how the product itself suppresses, enhances, or mimics the plastic signal. These effects can differ sharply between tap water, bottled water, and more complex products.
8. **Robustness** shows how small, deliberate changes in reagent strength, digestion time, or temperature affect the result. It confirms that the method holds up under realistic day-to-day variation.

ISO 24187:2023 provides principles, not numbers. Numerical acceptance criteria such as recovery ranges or precision thresholds must be written into the lab’s own protocol with reasoning that fits the product and use case. Values borrowed from unrelated pharmaceutical or food standards should be labeled as internal targets, not as ISO 24187:2023 requirements.

[See whether your current validation parameters support the claim you want to make.](https://www.wellnessqualityinstitute.com/?utm_term=microplastics-testing-methodology-validation&utm_campaign=ai_growth_agent)

## Contamination Control As A Core Part Of Validation

Contamination control is a validation requirement. Without it, blank data loses meaning, detection limits cannot be trusted, and blank correction fails, which leaves the entire dataset open to challenge.

Effective contamination control rests on three practices. Procedural and field blanks must travel with the sample from collection through analysis so any contamination introduced along the way appears in the blank instead of being mistaken for sample signal. Work should take place in a clean-air environment such as a laminar flow hood or HEPA-filtered cleanroom. Every tool, vessel, and instrument that touches the sample should be glass, metal, or another plastic-free material.

The scale of contamination in the published microplastics literature is large. [Munno et al. (2023, Chemosphere 333, 138883)](https://www.sciencedirect.com/science/article/pii/S0045653523009876) surveyed procedural blanks and found that blanks expected to be zero contained between 7 and 511 particles, with a mean near 80. The same survey reported that 82 percent of studies did not describe clean-air controls and 66 percent did not blank-correct their results. Uncorrected results cannot be interpreted against a contamination baseline.

Laboratory consumables can also seed false positives. [Witzig et al. (2020, Environmental Science & Technology 54, 12164–12172)](https://pubs.acs.org/doi/10.1021/acs.est.0c03742) showed that standard nitrile gloves shed stearate salt particles into wet-contact samples, creating infrared peaks that resemble polyethylene. [Clough et al. (2026, Analytical Methods 18, 2914–2926)](https://pubs.rsc.org/en/content/articlelanding/2026/ay/d5ay02105g) extended this to dry contact and measured about 2,000 false-positive particles per square millimeter of glove contact area. These stearate particles are Raman-inactive, so a Raman-based workflow can be contaminated without a clear spectral warning.

A [PNAS commentary](https://www.pnas.org/doi/10.1073/pnas.2411099121) on the [Qian et al. (2024, PNAS)](https://www.pnas.org/doi/10.1073/pnas.2300582121) nanoplastics study highlighted contaminated blanks and weak quality control. Those same controls sit at the heart of any defensible validation protocol and show how quickly a high-profile result can be questioned when contamination control is incomplete.

## Spike Recovery Criteria And What They Really Show

Spike recovery measures how much of a known quantity of target polymer particles the full workflow recovers. The workflow runs from sample collection through vessel contact, filtration, digestion, drying, transfer, and final detector classification. A spike that enters only at the instrument stage proves instrument visibility, not full-process performance.

A strong spike design is full-process, matrix-matched, and isotope-traced where possible. It uses particles that stand out from the native particle population without changing how the sample behaves. It also documents spike amount, particle number or mass, size distribution, polymer composition, shape, preparation, and homogeneity.

Real-world recovery is often lower and more variable than instrument specifications suggest. Rauert et al. (2025, Environmental Science & Technology 59, 1984–1994) reported spike recoveries from 7 percent to 109 percent across polymers in blood. Carboxylated polystyrene nanoparticles recovered at 17 percent in early runs and improved to 52 percent after preparation changes. Realistic limits of detection for polyethylene and PVC in blood, based on matrix-matched blanks, were 10 to 20 times higher than earlier nominal literature values.

Reference material quality shapes what spike data can prove. [Emteborg et al. (2026, Analytical and Bioanalytical Chemistry)](https://link.springer.com/article/10.1007/s00216-026-06758-x) showed that a reference material must be homogeneous and stable. Otherwise, variation in recovery reflects uneven particle distribution in the material, not lab performance. A salt-carrier reference material reached about 14 percent relative between-unit variability, which improved to about 7.9 percent after method development.

Representative reference materials for the smallest particles still do not exist. [Alnairat et al. (2026, Frontiers in Materials)](https://www.frontiersin.org/journals/materials/articles/10.3389/fmats.2026.1950397/full) found no certified reference materials for environmentally relevant nanoplastics and the smallest microplastics, which leaves uncertainty wide for those size ranges.

## How Blank Controls Shape Detection Limits

Blank controls sit at the base of every detection limit. The limit of detection, or LOD, is usually calculated as the blank mean plus three standard deviations. That calculation must use blanks from the real sample matrix, not vendor data from clean reference materials.

Blank correction is core arithmetic for defensible data. A result that has not been corrected against a contemporaneous blank cannot be interpreted, because the sample signal cannot be separated from contamination. The [Ciornii et al. (2025, Analytical Chemistry 97, 8719–8728)](https://doi.org/10.1021/acs.analchem.4c05403) interlaboratory comparison of 84 laboratories reported reproducibility values from roughly 45 percent to 129 percent across methods and polymers. The same reference material produced results that differed by factors of two to ten across laboratories. Strong blank discipline and contamination control are what turn that spread into comparable data.

For more detail on how blanks and reporting limits affect claim defensibility, see [Microplastics Lab Testing: Does Your Data Support A Claim?](https://www.wellnessqualityinstitute.com/articles/microplastics-lab-testing-verification-process/?utm_term=microplastics-testing-methodology-validation&utm_campaign=ai_growth_agent)

## How LOD And LOQ Affect “None Detected” Claims

The limit of detection, or LOD, is the lowest particle count that stands out from the blank signal. The limit of quantification, or LOQ, is the lowest amount that can be measured with acceptable accuracy and precision, supported by low-level data. The LOQ always sits above the LOD.

This distinction controls how to read a “none detected” result. A non-detect means none found above the reporting limit for the polymers screened in the lot tested. It does not mean none present. If the LOD came from clean reference materials instead of the real matrix, it will look lower than the method can truly support. Rauert et al. (2025) showed that realistic LODs in blood were 10 to 20 times higher than nominal literature values for the same polymers.

Instrument specifications also differ from practical detection limits. A [2026 review in Environmental Chemistry Letters (Vol. 24, 485–510)](https://link.springer.com/article/10.1007/s10311-026-01902-6) reported that FTIR spectroscopy has a nominal detection limit near 20 micrometers and Raman near 1 micrometer. In practice, studies often report about 50 micrometers for FTIR and about 10 micrometers for Raman, which shows the gap between theoretical resolution and demonstrated performance.

For a deeper look at how detection limits change the meaning of lab evidence, see [Microplastics Testing Limits and How to Judge the Evidence](https://www.wellnessqualityinstitute.com/articles/water-quality-month-microplastics/?utm_term=microplastics-testing-methodology-validation&utm_campaign=ai_growth_agent).

## Micro-FTIR, Micro-Raman, And Py-GC/MS In Validation

The three most common microplastics methods, micro-FTIR, micro-Raman, and Py-GC/MS, produce different types of output. Those differences control how validation data from each method can be used and compared.

Micro-FTIR and micro-Raman are particle-resolved and non-destructive. They report particle count, size, shape, and polymer identity for individual particles, and the filter can be archived for later review. Py-GC/MS is destructive and mass-based. It reports total polymer mass but does not provide particle count, size, or shape. Once a sample has been pyrolyzed, no particles remain for reanalysis.

Infrared methods also face a physical size limit called the diffraction wall. Mid-infrared wavelengths span roughly 6 to 20 micrometers, which creates a wall near 10 micrometers below which FTIR cannot reliably identify particles. Micro-FTIR usually reaches a lower size limit of about 10 to 20 micrometers in practice. Conventional Raman microscopy often reaches about 1 micrometer. As [Mallek and Barceló (2026, Journal of Xenobiotics 16(3), 93)](https://mdpi.com/2039-4713/16/3/93) note, no single technique can fully characterize all environmentally relevant size classes, so workflows remain method-dependent and incomplete.

The counts-versus-mass problem means that Py-GC/MS and spectroscopic methods cannot be compared on a single numeric scale. The table below shows why. Each method reports a different type of output and has a different validated size floor, so a validation protocol built for one method does not automatically transfer to another.

| Method | Validated Lower Size Limit | Output | Destructive |
| --- | --- | --- | --- |
| Micro-FTIR | About 10–20 µm in practice; example state water board method validated above 50 µm (Science and Medicine Group, 2026) | Particle count, size, shape, polymer identity ([Mallek & Barceló, 2026](https://mdpi.com/2039-4713/16/3/93)) | No |
| Micro-Raman | About 1 µm nominal; example state water board method validated above 20 µm (Science and Medicine Group, 2026) | Particle count, size, shape, polymer identity ([Mallek & Barceló, 2026](https://mdpi.com/2039-4713/16/3/93)) | No |
| Py-GC/MS | Not applicable, because there is no particle-size output and the method is mass-based only ([Mallek & Barceló, 2026](https://mdpi.com/2039-4713/16/3/93)) | Total polymer mass with no particle count, size, or morphology ([Mallek & Barceló, 2026](https://mdpi.com/2039-4713/16/3/93)) | Yes |

A practical reliability check is the two-method principle. This pairs a particle-based method with a mass-based method on matched portions of the same sample and treats any large divergence as information about method suitability for that product.

## Why Accredited Labs Still Report Different Results

Different laboratories often report different microplastics results because instrument type, spectral library, sample preparation, blank discipline, and analyst judgment all shape the output. These factors are not yet standardized tightly enough to guarantee matching results across labs.

![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.**

The [Ciornii et al. (2025, Analytical Chemistry 97, 8719–8728)](https://doi.org/10.1021/acs.analchem.4c05403) interlaboratory comparison involved 84 laboratories worldwide using two thermo-analytical and three spectroscopic methods on PET and PE reference powders. Reproducibility ranged from 62 to 117 percent for PE and 45.9 to 62 percent for PET by thermo-analytical methods. It ranged from 121 to 129 percent for PE and 64 to 70 percent for PET by spectroscopic methods. Tablet dissolution emerged as a particularly difficult step. These findings are feeding into ISO standardization work under ISO/TC 147/SC 2.

[Graf et al. (2026, Scientific Reports)](https://research.bangor.ac.uk/en/publications/instrument-dependent-variability-affects-both-microplastic-polyme) ran an interlaboratory comparison across seven countries where instrument manufacturer, instrument type, spectral library, and observer were the only variables. Those factors still produced strong instrument- and library-dependent effects despite shared protocols. The conclusion is clear. Protocol standardization alone cannot guarantee comparable results.

For validation, this means interlaboratory comparison belongs inside the validation evidence. Example state water board standard operating procedures were each validated through a [22-laboratory interlaboratory study](https://waterverge.com/news/ucmr6-microplastics-monitoring), which made that comparison part of the original validation basis.

## The 1–20 µm Fraction And The Real Meaning Of “None Detected”

The 1–20 micrometer particle-size fraction sits inside the example state regulatory definition of microplastics but outside the validated range of both example state standard operating procedures. That gap directly limits what any “none detected” result can claim.

Example state defines microplastics in drinking water as solid polymeric material with at least three dimensions greater than 1 nanometer and less than 5,000 micrometers. The two approved methods cover a narrower range. The example state water board infrared method is validated above 50 micrometers, and the Raman method is validated above 20 micrometers. The 1–20 micrometer fraction is not validated under either method. The definition reaches down to 1 nanometer, while the best validated methods begin at 20 or 50 micrometers, which are thousands of times larger.

Recovery shown above 50 micrometers cannot be stretched to cover the 1–20 micrometer fraction. The [2026 Environmental Chemistry Letters review (Vol. 24, 485–510)](https://link.springer.com/article/10.1007/s10311-026-01902-6) states that a defensible small-particle claim requires validation with appropriately sized and shaped particles, matrix spikes, recovery measurements, and clear reporting of the smallest validated size. A claim that does not state the validated size floor lacks a defensible boundary.

“None detected” is therefore a bounded statement. It means none found above the method floor for the screened polymers in the sampled lot. Knowing that boundary is what separates a result that can support a claim from one that cannot.

[Check whether your “none detected” language matches your method’s validated size range.](https://www.wellnessqualityinstitute.com/?utm_term=microplastics-testing-methodology-validation&utm_campaign=ai_growth_agent)

## How To Review A Lab’s Validation Documentation

Reviewing a laboratory’s validation documentation calls for a structured audit of the method, the product matrix, the contamination controls, and the data quality. The seven-step workflow below offers a framework that organizations can adapt for their own procurement or review processes.

1. Confirm the laboratory’s accreditation tier and confirm that the specific method and matrix appear within the accredited scope, not just that the lab holds [ISO/IEC 17025:2017](https://www.iso.org/standard/66912.html) in general.
2. Confirm the validated particle-size range and the reported lower method limit, and check whether your intended claim sits inside that range.
3. Confirm that procedural and field blanks were run and that results are blank-corrected. Uncorrected results cannot be interpreted against a contamination baseline.
4. Confirm that full-process, matrix-matched spike recovery data exist for every polymer you plan to report.
5. Confirm that LOD and LOQ were calculated from the blank distribution in the actual sample matrix, not from vendor specifications on clean reference materials.
6. Confirm that counts are reported by size fraction rather than as a single combined number.
7. Confirm chain of custody and data recency so the results match current production.

For organizations that already hold lab data and need an independent view of what it supports, the Wellness Quality Institute offers Plastic-Free Pathway Verification, governed by the standard WQI-CS-01. The Wellness Quality Institute reviews a company’s independent lab dataset, testing methodology, product scope, and supporting controls against defined criteria focused on particle size and polymer type, aligned with the example state water board drinking-water microplastics framework.

The Wellness Quality Institute does not run lab tests and does not certify that any product is free of plastic. Laboratories are qualified by accreditation tier rather than by name. Example state ELAP accreditation for the applicable method is preferred. ISO/IEC 17025 accreditation with the method and matrix in scope is accepted. Other independent laboratories may be conditionally acceptable through documented method-equivalence review. This lets companies confirm before commissioning testing whether their chosen lab can produce a reviewable dataset.

Every review ends in one of two outcomes. Standard Met carries a verification decision, a scope-locked license to use the Wellness Quality Institute mark, a public registry listing, and approved claim language. Standard Not Met is private, never described as a failed product, and can be resubmitted with updated information. A single assessment fee covers review, verification decision, and registry listing. Independent lab testing is arranged and billed separately. Phase 1 focuses on water and suitable simple-liquid products, where testing methods are most defensible.

>

*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 state approval, government certification, or health or safety certification.*

[Request an independent review of your current microplastics data and claims.](https://www.wellnessqualityinstitute.com/?utm_term=microplastics-testing-methodology-validation&utm_campaign=ai_growth_agent)

## Frequently Asked Questions

### Does ISO 24187:2023 Specify Numerical Acceptance Criteria For Spike Recovery Or Precision?

ISO 24187:2023 does not specify numerical acceptance limits. It provides a framework and general principles for microplastics analysis. It does not mandate specific recovery percentages, precision thresholds, or signal-to-noise ratios. Numerical criteria must be written into the laboratory’s own validation protocol using reasoning that fits the matrix, size range, and polymer panel under validation. Values drawn from pharmaceutical or food-method standards, such as 70 to 120 percent recovery ranges, are not ISO 24187:2023 requirements and should be labeled clearly as internal targets.

### How Many Procedural Blanks Do I Need For A Defensible Microplastics Dataset?

There is no single universal number, but the principle is clear. Blanks must be frequent enough to describe the blank distribution in the real sample matrix, because the LOD is calculated from that distribution. Field blanks should travel with every sample batch from collection through analysis. Procedural blanks should accompany each analytical run. As the literature survey cited earlier showed, most published data cannot be interpreted against a contamination baseline. A defensible dataset needs enough blanks to calculate a meaningful mean and standard deviation, and every reported result must be blank-corrected.

### Can A Laboratory Accredited For Example State Method Report Results In The 1–20 µm Fraction?

A laboratory accredited for the example state method can report results within that method’s validated range. The example state Raman method is validated for particles greater than 20 micrometers through 5,000 micrometers. The 1–20 micrometer fraction falls inside the regulatory definition of microplastics but outside the validated range of both example state procedures. Recovery demonstrated for larger particles cannot be assumed for smaller particles, because extraction efficiency, filtration losses, and identification accuracy all change with size. Any claim about the 1–20 micrometer fraction would require separate validation using appropriately sized particles, matrix spikes, and recovery measurements for that range.

### What Does “None Detected” Mean In A Microplastics Laboratory Report?

“None detected” means no particles were found above the method’s reporting limit for the specific polymers screened in the lot tested. It does not mean the product contains no plastic. The reporting limit is set by the method’s detection floor, which for infrared methods is typically around 50 micrometers in practice and for Raman around 10 to 20 micrometers in practice. Everything below that floor is invisible to the method. A “none detected” result is a bounded statement about what the method could see. Interpreting it correctly requires knowing the reporting limit, the validated size range, and the polymer panel.

### Why Can Two Accredited Laboratories Report Different Results For The Same Sample?

Accreditation confirms that a laboratory runs a quality system and has shown competence for a defined scope. It does not guarantee that two laboratories using different instruments, spectral libraries, and analysts will produce the same result. An interlaboratory comparison across seven countries found that instrument manufacturer, instrument type, spectral library, and observer were the only variables between labs, and those factors still produced strong instrument- and library-dependent effects. The 84-laboratory study by Ciornii et al. (2025) reported reproducibility values from roughly 45 percent to 129 percent across methods and polymers. Protocol standardization alone cannot ensure comparability. Interlaboratory comparison data belongs inside the validation evidence.

### Is A Laboratory Report Enough To Support A Public Claim About Plastic Content?

A laboratory report documents procedures, equipment, materials, raw data, and the lab’s interpretation. On its own, it does not prove that the method was validated for the matrix, that reporting limits are adequate, that blanks were run and results blank-corrected, or that the polymer panel matches the claim. Without independent review of those elements, a lab report is a number without context. Buyers, retailers, and regulators also discount self-reported results because the company has a direct interest in the interpretation. Independent review of the dataset, method, and controls is what turns a lab report into a defensible market claim.

### What Documentation Should I Request Before Commissioning Microplastics Testing?

Before commissioning testing, request the laboratory’s validation report for your product matrix, including the validated size range, LOD and LOQ calculations, spike recovery data by polymer, blank protocols, and accreditation scope that lists the specific method and matrix. Ask for example reports that show how results are blank-corrected and broken out by size fraction, and confirm that the polymer panel and reporting limits align with the claim you intend to make.

## Read Next

- [Microplastics Testing Validation: A Whole-Workflow Guide](https://www.wellnessqualityinstitute.com/articles/microplastics-testing-method-validation/?utm_term=microplastics-testing-methodology-validation&utm_campaign=ai_growth_agent)
- [How To Evaluate Microplastics Testing From Vendors](https://www.wellnessqualityinstitute.com/articles/how-to-evaluate-microplastics-testing/?utm_term=microplastics-testing-methodology-validation&utm_campaign=ai_growth_agent)
- [Microplastics Testing Methodology & Verification Standards](https://www.wellnessqualityinstitute.com/articles/microplastics-testing-methodology-standards/?utm_term=microplastics-testing-methodology-validation&utm_campaign=ai_growth_agent)
- [Microplastics Lab Testing: Does Your Data Support A Claim?](https://www.wellnessqualityinstitute.com/articles/microplastics-lab-testing-verification-process/?utm_term=microplastics-testing-methodology-validation&utm_campaign=ai_growth_agent)
- [What Microplastics Testing Proves and Where It Stops](https://www.wellnessqualityinstitute.com/articles/what-microplastics-testing-proves/?utm_term=microplastics-testing-methodology-validation&utm_campaign=ai_growth_agent)

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      - **Text:** There is no single universal number, but the principle is clear. Blanks must be frequent enough to describe the blank distribution in the real sample matrix, because the LOD is calculated from that distribution. Field blanks should travel with every sample batch from collection through analysis. Procedural blanks should accompany each analytical run. As the literature survey cited earlier showed, most published data cannot be interpreted against a contamination baseline. A defensible dataset needs enough blanks to calculate a meaningful mean and standard deviation, and every reported result must be blank-corrected.
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    - **Name:** Can A Laboratory Accredited For Example State Method Report Results In The 1–20 µm Fraction?
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      - **Text:** A laboratory accredited for the example state method can report results within that method’s validated range. The example state Raman method is validated for particles greater than 20 micrometers through 5,000 micrometers. The 1–20 micrometer fraction falls inside the regulatory definition of microplastics but outside the validated range of both example state procedures. Recovery demonstrated for larger particles cannot be assumed for smaller particles, because extraction efficiency, filtration losses, and identification accuracy all change with size. Any claim about the 1–20 micrometer fraction would require separate validation using appropriately sized particles, matrix spikes, and recovery measurements for that range.
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    - **Name:** What Does “None Detected” Mean In A Microplastics Laboratory Report?
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      - **Text:** “None detected” means no particles were found above the method’s reporting limit for the specific polymers screened in the lot tested. It does not mean the product contains no plastic. The reporting limit is set by the method’s detection floor, which for infrared methods is typically around 50 micrometers in practice and for Raman around 10 to 20 micrometers in practice. Everything below that floor is invisible to the method. A “none detected” result is a bounded statement about what the method could see. Interpreting it correctly requires knowing the reporting limit, the validated size range, and the polymer panel.
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    - **Name:** Why Can Two Accredited Laboratories Report Different Results For The Same Sample?
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      - **Text:** Accreditation confirms that a laboratory runs a quality system and has shown competence for a defined scope. It does not guarantee that two laboratories using different instruments, spectral libraries, and analysts will produce the same result. An interlaboratory comparison across seven countries found that instrument manufacturer, instrument type, spectral library, and observer were the only variables between labs, and those factors still produced strong instrument- and library-dependent effects. The 84-laboratory study by Ciornii et al. (2025) reported reproducibility values from roughly 45 percent to 129 percent across methods and polymers. Protocol standardization alone cannot ensure comparability. Interlaboratory comparison data belongs inside the validation evidence.
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    - **Name:** Is A Laboratory Report Enough To Support A Public Claim About Plastic Content?
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      - **Text:** A laboratory report documents procedures, equipment, materials, raw data, and the lab’s interpretation. On its own, it does not prove that the method was validated for the matrix, that reporting limits are adequate, that blanks were run and results blank-corrected, or that the polymer panel matches the claim. Without independent review of those elements, a lab report is a number without context. Buyers, retailers, and regulators also discount self-reported results because the company has a direct interest in the interpretation. Independent review of the dataset, method, and controls is what turns a lab report into a defensible market claim.
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      - **Text:** Before commissioning testing, request the laboratory’s validation report for your product matrix, including the validated size range, LOD and LOQ calculations, spike recovery data by polymer, blank protocols, and accreditation scope that lists the specific method and matrix. Ask for example reports that show how results are blank-corrected and broken out by size fraction, and confirm that the polymer panel and reporting limits align with the claim you intend to make.

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  - **Description:** The Wellness Quality Institute explains how to validate microplastics testing methods for defensible, credible data. Get expert guidance today.
  - **DateModified:** 2026-10-15T10:45:28.764Z
  - **Image:** https://cdn.aigrowthmarketer.co/1784829388732-c6255482b477.webp, https://cdn.aigrowthmarketer.co/1784829410323-fb401fc7b1e4.webp, https://cdn.aigrowthmarketer.co/1784829434095-0fc8fbcf29fa.webp
  - **InLanguage:** en-US
    **Person:**

    - **Name:** Scott Steveson
    - **JobTitle:** Specialist
    - **Description:** Scott Stevenson is part of the Wellness Quality Institute team, where he supports WQI’s work to advance product transparency, credible verification, and greater consumer trust. His background spans ethics and compliance, corporate trust, and responsible business, including experience with Ethisphere Institute and global companies navigating evolving standards and stakeholder expectations.
      **Organization:**

      - **Name:** Wellness Quality Institute
      - **Url:** https://www.wellnessqualityinstitute.com/
    **Organization:**

    - **Name:** The Wellness Quality Institute
    - **Url:** https://wellnessqualityinstitute.com


---

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- **MCP Server (Streamable HTTP):** [https://www.wellnessqualityinstitute.com/articles/.well-known/mcp](https://www.wellnessqualityinstitute.com/articles/.well-known/mcp)

## Citations

- [Credible Plastic-Free Claim Language: A Practical Playbook](https://www.wellnessqualityinstitute.com/articles/credible-plastic-free-claim-language)
- [Retail Supplier Plastic Reduction Compliance & Proof](https://www.wellnessqualityinstitute.com/articles/retail-supplier-plastic-compliance-guide)
- [How To Verify Plastic Contamination In Protein Powder](https://www.wellnessqualityinstitute.com/articles/verify-protein-powder-plastic-contamination)
- [Plastic Claim Substantiation: Evidence Before You Claim](https://www.wellnessqualityinstitute.com/articles/plastic-claim-substantiation-evidence-requirements)
- [How To Make Plastic Reduction Claims That Hold Up](https://www.wellnessqualityinstitute.com/articles/substantiate-clean-label-plastic-reduction)

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