Microplastics Testing For Retailers: Labs, Methods & Claims

Written by: Scott Steveson, Specialist, Wellness Quality Institute

Key Takeaways

• Retailers face rising pressure from consumers, regulators, and litigators to substantiate plastic-related claims with credible testing.

• Testing is most defensible for simple liquid products such as bottled water, followed by food contact packaging, synthetic textiles, and personal care products.

• Choosing an ISO/IEC 17025-accredited lab with the right microplastics method and product matrix in scope is essential, along with understanding that current methods cannot reliably measure particles below 20 µm.

• “None detected” results only apply above the method’s detection floor and never prove a product is plastic-free, so absolute claims such as “microplastic-free” carry legal risk.

• The Wellness Quality Institute offers independent Plastic-Free Pathway Verification that reviews third-party lab data against defined standards to support specific, defensible environmental claims; see how verification works.

Retailers now face growing pressure to back up plastic-related claims with real data. Consumers are asking harder questions, California regulations take effect in October 2026, and the FTC Green Guides create legal risk for unsubstantiated claims. This guide walks retailers through what to test, how to choose a lab, how to read results, and how to turn those results into claims that hold up.

What To Test: Priority Product Categories And Materials

Retailers get the clearest answers from microplastics testing on simple liquid products such as bottled water and beverages. These liquids contain few particles to begin with, so laboratory methods perform more reliably.

After beverages, focus on other high-impact categories where plastics directly touch people or products.

• Bottled Water And Beverages, the most defensible starting point; packaging, especially caps, can itself introduce plastic particles.

• Food Contact Packaging, where materials that touch food or drink should be screened for shedding risk.

• Textiles, since synthetic fabrics shed microfibers; testing methods exist but are less standardized than those for water.

• Personal Care Products, which fall under EU REACH restrictions on intentionally added microplastics that phase in for cosmetics between 2025 and 2035.

California’s regulatory definition of microplastics covers solid plastic particles from 1 nanometer up to 5,000 micrometers. That range extends far beyond what any current validated method can measure. Retailers need to understand this gap before commissioning tests or drafting claims.

How To Choose A Microplastics Testing Lab

The Wellness Quality Institute recommends starting with accreditation when selecting a lab. ISO/IEC 17025 accreditation, the international standard for laboratory competence, must list the specific microplastics method and your product type within the accredited scope. A lab accredited for metals in soil, for example, is not automatically qualified for microplastics in beverages.

California ELAP (Environmental Laboratory Accreditation Program) accreditation for the relevant State Water Board method counts as one accreditation tier under the Wellness Quality Institute (WQI) framework.

Use these criteria when you screen laboratories:

• ISO/IEC 17025 Accreditation that explicitly includes the microplastics method and your product matrix.

• California ELAP Accreditation for the applicable State Water Board method, where that option exists.

• Experience With Your Product Category, supported by case studies or references in your matrix.

• Clear Information On Detection Limits, Polymer Panels, And Contamination Controls, shared in writing before you sign.

Laboratories with established microplastics capability include Eurofins Environment Testing, SGS, and EMSL Analytical. WQI does not endorse specific laboratories. It qualifies labs by accreditation tier rather than by name.

Before you approve any proposal, ask each lab about its lower detection limit, the list of polymers it can identify, how it controls contamination, and which blanks it runs and reports.

How Microplastics Testing Methods Work: FTIR, Raman, And LDIR

Three spectroscopic methods dominate commercial microplastics testing. The table below compares how each method works and the smallest particle size it typically detects, which directly affects what your results can show.

Method	How It Works	Typical Detection Floor
FTIR (Fourier Transform Infrared)	Identifies polymers by their infrared absorption signature, using dry samples.	Around 10 µm, depending on configuration
Raman Spectroscopy	Measures molecular vibration, works well on wet samples, and can be affected by fluorescence.	Around 1 µm, depending on configuration
LDIR (Laser Direct Infrared)	Uses automated chemical imaging that runs faster than most FTIR or Raman setups with less sample preparation.	Typically 20–500 µm in commercial systems

The California State Water Board’s two published methods, SWB-MP1-rev1 (infrared spectroscopy, validated above 50 µm) and SWB-MP2-rev1 (Raman spectroscopy, validated above 20 µm), provide the strictest public reference today. A critical technical limit applies across methods: no validated method reliably detects particles below 20 µm, and nanoplastics below 1 µm remain beyond current commercial measurement. That boundary shapes what any lab report can say and what it must leave out.

How To Interpret Lab Results: Detection Limits And “None Detected”

“None detected” means the lab did not find particles above the method’s detection limit, for the polymers tested, in the specific sample analyzed. A report with that language never proves that a product is plastic-free.

Consider a report that states “no microplastics detected” using a method validated above 50 µm. That report says nothing about particles between 1 and 50 µm. The limit of detection is the most important figure on the page because it defines the smallest particle or mass the method can reliably find. As noted earlier, the 1–20 µm fraction is not validated under either California method. Retailers who overlook this gap risk overclaiming and facing legal and reputational fallout.

Using Results For Marketing Claims: Avoiding Greenwashing

Absolute phrases such as “plastic-free” or “microplastic-free” go beyond what current science can support. Under the FTC Green Guides, environmental claims must be truthful, supported before publication, and not misleading. Class-action lawsuits increasingly target companies whose plastic claims lack solid backing.

The Wellness Quality Institute (WQI) offers independent verification for US companies that want to avoid these pitfalls. WQI does not run laboratory tests. Instead, it reviews a company’s third-party lab data against a defined standard, WQI-CS-01, which aligns with California’s drinking-water microplastics reference framework.

A Standard Met outcome includes a verification decision, approved claim language tied to a specific scope, and a public registry listing. WQI verification confirms genuine progress along a pathway toward plastic-free standards and does not function as a certification or a promise of zero plastic.

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.

Explore Plastic-Free Pathway Verification for your company

Common Mistakes And Misinterpretations In Microplastics Claims

• Assuming “None Detected” Equals “Plastic-Free”, when it only means none found above the detection limit, for the polymers tested, in that sample.

• Relying On Self-Reported Data Without Independent Review, since the market often treats internal testing as marketing, regardless of rigor.

• Making Company-Wide Claims From A Single Test, even though verification always applies to a defined product, dataset, and production period.

• Confusing Detection With Absence, because no method can prove a negative across all particle sizes and polymer types.

• Selecting A Lab Without Checking Accreditation Scope, as a lab accredited for one matrix or analyte may not be accredited for microplastics in your specific product.

Get your data verified for a defensible claim

Practical Checklist For Retailers

Use this checklist as a step-by-step path from choosing products to making a defensible microplastics claim.

• Identify priority product categories and start with simple liquid products where methods are most defensible.

• Select a qualified laboratory with ISO/IEC 17025 or California ELAP accreditation for the applicable method.

• Confirm that the chosen method matches your product matrix before commissioning tests.

• Ask about detection limits, polymer panels, blanks, and contamination controls in writing.

• Interpret results with full context and remember that “none detected” is always bounded by the method’s detection floor.

• Seek independent third-party verification before you publish environmental claims.

• Use only approved claim language that matches your verified scope.

Cost Considerations And Budgeting For Testing And Verification

Microplastics testing costs vary significantly by method, product matrix, and sample count. Commercial laboratories do not publish rate cards, so each project receives a custom quote.

Expect higher prices for complex products, tighter detection limits, or broader polymer panels. The Wellness Quality Institute charges an assessment fee that covers data review, the verification decision, and the registry listing, while independent labs bill separately for testing. Plan for both testing and independent verification as separate lines in your sustainability and compliance budget.

Frequently Asked Questions

What Is Microplastics Testing For Retailers?

Microplastics testing is laboratory analysis of products, packaging, or materials that looks for and measures plastic particles. Labs typically use spectroscopic methods such as FTIR or Raman, which identify polymer types by their chemical fingerprints.

For retailers, testing serves two main purposes. It shows what a product actually contains and it generates data that may support environmental claims. Testing can establish presence, because finding a particle is comparatively straightforward. It cannot prove complete absence, because every result is limited by the detection floor, the polymers in the test panel, and the production lot sampled.

How Much Does Microplastics Testing Cost?

No standard price list exists for microplastics testing. Commercial laboratories quote projects individually based on the analytical method, the product matrix, the number of samples, the particle-size range, and the polymer panel.

Retailers should budget for both laboratory testing and independent verification as separate items. Skipping independent review to save money often backfires, because a lab report alone does not automatically translate into a defensible market claim.

What Do The Main Testing Methods Actually Measure?

FTIR spectroscopy identifies polymers by the way they absorb infrared light, and each polymer type produces a distinctive spectral fingerprint. California’s SWB-MP1-rev1 method, which relies on infrared spectroscopy, is validated for particles above 50 micrometers (µm).

Raman spectroscopy measures molecular vibration and works well on wet samples. California’s SWB-MP2-rev1 Raman method is validated above 20 µm. LDIR (Laser Direct Infrared) is an automated imaging system that collects infrared spectra quickly and typically covers 20–500 µm in commercial systems.

All three methods identify polymer types and particle sizes within their validated ranges. However, none can detect nanoplastics smaller than 1 µm, and, as noted earlier, the 1–20 µm fraction is not validated under either California method. Pyrolysis GC-MS is a different technique that measures total polymer mass but does not provide particle size or count.

Can A Product Be Verified As Plastic-Free?

No current laboratory technology can confirm the complete absence of plastic across every particle size, polymer type, and production lot. As mentioned earlier, California’s definition of microplastics reaches down to 1 nanometer, while the best validated methods begin at 20 or 50 micrometers. That gap means any claim of total absence goes beyond what the science can support.

Independent verification through WQI’s Plastic-Free Pathway Verification program can confirm that a company’s laboratory data meets defined review criteria aligned with California’s drinking-water microplastics framework, within the tested particle-size range and polymer panel. That outcome creates a defensible, honest claim, unlike “plastic-free,” which current science cannot substantiate.

How Do I Evaluate A Supplier’s Microplastics Claim?

Begin with the full laboratory report rather than a marketing summary. Confirm that ISO/IEC 17025 accreditation covers the specific microplastics method and the product matrix in question, not just the lab in general.

Check the detection limit, because a “none detected” result only has meaning relative to the smallest particle size the method can see. Review the polymer panel, since a test that screens for five polymers says nothing about the rest. Ask whether procedural blanks and contamination controls were run and reported.

Finally, look for independent review by a third party. A supplier’s own interpretation of its test results carries less weight than a finding reviewed by an independent body that has no commercial stake in the outcome.

Read Next

• Microplastics Testing Limits and How to Judge the Evidence

• Microplastics Claim Verification: What Lab Data Can Prove

• What Microplastics Testing Proves and Where It Stops

• Microplastics in Drinking Water: Testing Explained

• Microplastics in Water: What Brands Need to Know