Summary

A cosmetic-grade TiO₂ or ZnO material should not be approved as nano or non-nano only because its file package contains an average particle size, an oxide assay, a surface-treatment name, and a signed declaration.

The approval question is narrower:

Do the submitted particle data, composition records, test methods, and commercial controls support the claimed status of the exact grade being purchased?

A complete document set may still fail this test when its reports describe different product codes, material states, coating stages, batches, or manufacturing routes.

Keep Three Approval Decisions Separate

Nano/non-nano review becomes unreliable when three different decisions are compressed into one “compliant” conclusion.

Particle Classification

This decision asks whether the measured material meets the applicable definition of a nanomaterial.

The answer depends on:

• the definition being applied;
• the particle population measured;
• whether the distribution is number-, volume-, intensity-, or mass-based;
• whether constituent particles or larger associated structures were evaluated;
• whether the method and sample preparation support the conclusion.

A signed declaration records the supplier’s interpretation. It does not replace the underlying evidence.

Target-Market Form Matching

This decision asks whether the grade corresponds to the material form permitted or assessed for its intended market and application.

For the EU market, the current consolidated Regulation (EC) No 1223/2009 on cosmetic products separates the general nanomaterial definition from the specific TiO₂ (nano) and ZnO (nano) forms listed in Annex VI. The relevant entries address characteristics such as particle-size distribution, purity, crystal structure, morphology, surface treatment, solubility, and restrictions associated with inhalation exposure.

Matching the substance name or CAS number alone does not establish that a commercial grade corresponds to an allowed nano form.

A material may meet a nano definition without matching the specific form required for the intended use. A non-nano declaration may also be insufficient when it does not identify the definition or market on which the conclusion is based.

Commercial Qualification

This decision asks whether future commercial batches will remain equivalent to the evaluated material.

A regulatory form match does not establish commercial qualification unless particle characteristics, coating composition, and material identity remain controlled through:

• approved specification limits;
• representative batch data;
• production-route consistency;
• periodic or routine characterization;
• change notification;
• defined requalification triggers.

A valid result from one sample cannot prove continued commercial control when the relevant attribute appears only as a typical value.

Build the Material Identity Before Reviewing Particle Data

The document review should begin with the exact commercial grade rather than the reported particle-size number.

A traceable identity chain should connect:

Product code → supplied form → surface treatment → composition → tested batch → particle report → commercial specification

The following information should remain consistent across the specification, composition declaration, particle report, batch COA, sample label, and nano/non-nano statement:

• trade name and product code;
• powder, dispersion, slurry, or masterbatch form;
• coated or uncoated status;
• surface-treatment identities;
• oxide content and reporting basis;
• tested batch or representative sample;
• report date and version;
• manufacturing route or site where relevant;
• target market and intended use.

This identity check is particularly important when reviewing cosmetic ingredients and personal care materials. Evidence generated for a dry oxide cannot automatically be transferred to a predispersed grade containing a carrier, dispersant, stabilizer, or additional processing components.

Formal approval should be held when:

• microscopy was performed on an untreated precursor while the supplied grade is coated;
• the particle report refers only to a trade-name family;
• a dry powder was tested but the purchased product is a liquid dispersion;
• the composition was changed after particle characterization;
• the report cannot be linked to the submitted batch;
• the declaration does not identify its classification basis.

The files may all be genuine. They still do not form a valid evidence chain when they describe different material states.

Why One Particle-Size Number Cannot Prove Nano or Non-Nano Status

An Average or D50 Does Not Describe the Full Distribution

A statement such as “average particle size: 150 nm” does not mean every particle is above 100 nm.

The reviewer must identify:

• whether the result is a mean, median, mode, D50, or another percentile;
• whether the distribution is number-, volume-, intensity-, or mass-based;
• whether the full distribution is available;
• whether the lower-size population was evaluated;
• whether the result applies to the commercial grade or a development sample.

A volume-based result may be dominated by larger particles. A smaller-particle population can have limited influence on volume-weighted data while representing a larger share of the number-based population.

D50 identifies a midpoint under one calculation basis. It does not describe the lower tail and cannot prove that the complete particle population is above a selected size.

Constituent Particles Are Not the Same as Aggregates or Agglomerates

Particle reports may describe different physical objects:

• Constituent or primary particles: the smaller structural units;
• Aggregates: strongly bonded or fused particle structures;
• Agglomerates: more loosely associated particle groups;
• Hydrodynamic structures: particles or particle groups behaving in a selected liquid.

A micrometre-scale agglomerate does not prove that its constituent particles are non-nano.

Dispersion-based methods may report apparent size in a liquid. Electron microscopy may provide more direct information about constituent dimensions and morphology. Neither result supports a classification conclusion without suitable sampling, preparation, measurement, and data treatment.

Sample Preparation Can Change the Measured Population

Particle-size results may change with:

• dispersion medium;
• sample concentration;
• dispersant type;
• mixing or sonication conditions;
• preparation time;
• delay before measurement;
• sedimentation;
• image preparation;
• particle segmentation and counting rules.

Insufficient dispersion may leave large agglomerates intact. Aggressive preparation may separate loosely associated particles.

Both measurements can be technically valid for their preparation conditions. They may not answer the same classification question.

A numerical result without a clear preparation protocol cannot show whether the measured population represents the commercial powder, a prepared suspension, or an artificially altered dispersion state.

Detection Is Not Quantification

“Particles below a selected size were detected” confirms observation under the test conditions. It does not establish their proportion in the complete population.

“No particles below a selected size were detected” does not prove absolute absence.

The interpretation depends on:

• detection capability;
• minimum reliably measurable dimension;
• number of particles examined;
• field selection;
• particle-counting rules;
• sample representativeness;
• statistical treatment.

Detection asks whether something was observed. Quantification estimates how much of the relevant population is present.

A non-detect statement should not support approval when the method cannot evaluate the particle fraction required by the applicable definition.

The SCCS Guidance on the Safety Assessment of Nanomaterials in Cosmetics, SCCS/1655/23 is intended for nanomaterial safety-assessment dossiers rather than routine batch release. Its characterization logic remains useful for supplier-file review because it addresses number-based particle-size distribution, morphology, aggregation and agglomeration, surface characteristics, composition, method validity, and batch information. It also recommends complementary particle-size methods, including electron microscopy.

The guidance can help identify evidence gaps. It should not be converted mechanically into a requirement that every parameter appear on every batch COA.

Surface Treatment and Composition Must Describe the Finished Grade

“Alumina-coated TiO₂” or “silane-treated ZnO” is not a complete material description.

The review should establish:

• each surface-treatment component;
• whether the grade is singly or multiply treated;
• whether the treatment is deposited, bonded, adsorbed, or blended;
• whether its quantity is controlled;
• whether processing aids remain in the product;
• whether particle characterization occurred before or after treatment;
• whether coating changes require notification.

Surface treatment can affect dispersion behavior, surface chemistry, formulation compatibility, particle interaction, and the relationship between oxide content and total delivered mass.

A particle report for an untreated oxide may describe the core material. It cannot independently characterize the finished coated grade.

Analytical evidence also needs to remain within its actual scope. A spectrum may support chemical identification. Elemental analysis may support the presence of an inorganic coating component. Neither result automatically proves coating uniformity, complete surface coverage, or the amount applied.

Oxide Assay Is Not the Complete Composition

A coated powder may contain:

• TiO₂ or ZnO;
• inorganic coating components;
• organic treatment agents;
• residual process components;
• moisture or volatile matter.

A dispersion may also contain a carrier, dispersant, stabilizer, or other formulation aids.

An oxide result should identify:

• the analyte being measured;
• whether it is expressed as TiO₂, ZnO, titanium, or zinc;
• whether the value is reported as supplied, on a dry basis, or on another defined basis;
• whether coating components remain in the sample mass;
• whether moisture or volatiles are corrected;
• whether it applies to powder solids or the complete dispersion;
• whether it is a batch result, specification limit, or typical value.

A dry-basis result and an as-supplied result answer different questions. The distinction affects formulation dosing, exposure calculations, incoming-control limits, cost comparison, and batch-yield calculations.

Area Purity Does Not Establish Coating Level

An organic coating agent or dispersant may be described as “99% by HPLC area.”

That result may describe the chromatographic profile of the coating raw material. It does not establish:

• how much was applied;
• how much remains on the particles;
• its percentage in the finished grade;
• whether other organic components are present.

The difference between HPLC area purity and quantitative assay matters when the purity of a treatment ingredient is presented as evidence for the composition of the final mineral powder or dispersion.

Data Distinctions That Change the Approval Decision

A further distinction applies to the whole file package:

Document existence is not evidence sufficiency.

A signed declaration proves that a statement was issued. It does not prove that the conclusion is supported by the correct method, batch, coating state, or commercial grade.

Cross-Check the Evidence as One System

The objective is not to collect the largest number of files. It is to determine whether the available files describe one controlled material.

Sample, Pilot, and Bulk Decisions Need Different Evidence

Pilot processing may alter the agglomeration state observed in the formulation through high-shear mixing, milling, wetting order, concentration, or hold time. These changes do not automatically redefine the incoming raw material, but they can affect process behavior and the interpretation of formulation-stage measurements.

Complete particle characterization may not be necessary for every shipment. Commercial qualification still requires a control strategy connecting release tests, process controls, periodic characterization, and change management to the approved grade identity.

Why Complete File Packages Still Fail Approval

In supplier-document reviews, a signed nano or non-nano declaration is often treated as the fastest way to close the classification question. The more difficult issue is whether the declaration is connected to the rest of the evidence.

Consider this file pattern:

• the TDS provides a volume-based D50 for the finished powder;
• the microscopy report covers an uncoated precursor;
• the composition statement describes an alumina- and silane-treated grade;
• the COA reports oxide content and moisture;
• the nano statement covers a trade-name family without a batch or report reference.

None of the documents must be false for the approval conclusion to fail. The package does not describe one exact material at one defined manufacturing stage.

Particle status should be managed as a controlled grade-identity attribute. Product code, particle distribution, crystal form, morphology, coating system, composition, manufacturing route, report version, and market basis should remain connected under change control.

Application performance cannot repair a broken evidence chain. A formulation may show acceptable dispersion, stability, appearance, or UV performance while the documentation remains insufficient.

Performance testing answers whether the tested sample works. It does not prove:

• the dimensions of its constituent particles;
• the classification basis used;
• the composition of the finished grade;
• the consistency of future commercial batches.

R&D teams should record formulation performance and raw-material identity as separate conclusions. Quality teams should test continuity across documents rather than count how many documents exist. Procurement teams should not extend sample approval into routine purchasing until the identity-critical attributes are commercially controlled.

Questions That Can Change the Decision

Before approval, the buyer should be able to answer eight questions:

1. Which exact product code, supplied form, production site, and batch were characterized?
2. Was the tested material uncoated oxide, coated powder, dispersion, slurry, or masterbatch?
3. Which nano definition, target market, and intended application were used?
4. Does the particle result describe constituent particles, aggregates, agglomerates, or hydrodynamic structures?
5. What distribution basis, preparation method, imaging approach, and counting rules were applied?
6. Which surface-treatment and formulation components are present, and how are their identities and levels controlled?
7. Is oxide content reported as supplied, on a dry basis, or on another defined basis?
8. Which particle, coating, composition, process, or site changes trigger notification and requalification?

The answer does not need to disclose the complete manufacturing process. It must be detailed enough to establish that the approval conclusion applies to the purchased grade.

Minimum Evidence for Final Approval

A defensible approval record should identify:

• the exact product code and material form;
• the evaluated batch or representative batches;
• the target market and intended application;
• the classification definition used;
• the particle population and distribution basis evaluated;
• the analytical methods and preparation conditions reviewed;
• the surface-treatment and complete composition;
• the commercial specification limits;
• unresolved assumptions or restrictions;
• the changes requiring requalification;
• the approved purchasing stage.

The final status should be explicit: exploratory sample, qualified sample, controlled pilot use, approved commercial supply, or qualification hold.

A high oxide assay cannot replace particle characterization. A large D50 cannot replace a distribution. A coating name cannot replace a composition statement. A signed declaration cannot replace evidence linked to the exact commercial grade.

Buyers requesting cosmetic TiO₂ or ZnO can include the target market, supplied form, required particle status, surface treatment, composition expectations, qualification stage, and document scope in a chemical raw material RFQ. ChemicalCell can then review grade availability and the supporting document requirements before sample or commercial confirmation.