To verify a product identified as CAS 28211-18-9; 77035-98-4, do not rely on the numbers alone. Ask the supplier to state what each CAS number represents, then compare that explanation with the product name, composition information, Safety Data Sheet (SDS), Technical Data Sheet (TDS), and lot-specific Certificate of Analysis (COA). If the documents do not clearly explain whether the numbers refer to one ingredient, related identities, or a mixture, pause qualification and request written clarification before approving a purchase.
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This guide is for cosmetic ingredient buyers, formulators, quality teams, and procurement professionals evaluating supplier documentation. It provides a practical verification process without assuming that the two identifiers are interchangeable or that either number, by itself, confirms a particular grade or performance profile.
This guide is intended for organizations sourcing a cosmetic chemical or polymer ingredient under one or both of the listed CAS numbers. It is useful when a document lists two CAS identifiers, when supplier paperwork uses different names for what appears to be the same material, or when a buyer needs to establish an internal approval specification. It can also help procurement and technical teams align on what must be verified before requesting samples or placing a production order.
The CAS numbers supplied in a product inquiry are starting points for document review, not a complete purchasing specification. A buyer still needs to confirm the material’s stated identity, grade, relevant quality attributes, intended application, and applicable regulatory documentation. If the product is described as a VP/alkene copolymer or another polymer type, ask the supplier to confirm that description rather than relying on an assumed match between a trade name and a CAS number.
A reliable identity review connects the identifier to the supplier’s product name and the material described in its documentation. Ask whether each CAS number identifies the supplied substance, a constituent, an alternative identifier, or another aspect of the product. The answer should be clear enough for your quality team to record and should not conflict with the SDS or other technical documents.
Do not infer that two CAS numbers necessarily describe the same substance, a blend, or interchangeable grades. The semicolon in a product inquiry may simply reflect how the identifiers were entered; it does not explain their relationship. If the supplier cannot clarify the listing, treat identity as unresolved and avoid using the product in a validated formulation or approved bill of materials.
| Document | What to check |
|---|---|
| Product label or quotation | Product name, grade, supplier identity, packaging, and listed CAS number or numbers. |
| SDS | Product identification and supplier details, including whether the identifiers match the supplier’s explanation. |
| TDS | Described material characteristics, recommended handling or use information, and stated test methods where applicable. |
| COA | Lot or batch reference, reported test results, units, methods, and acceptance limits for the supplied lot. |
| Regulatory or composition statement | Information needed for your market, product category, and internal compliance review. |
Send the supplier the exact identifiers as they appear in your inquiry: CAS 28211-18-9 and CAS 77035-98-4. Ask the supplier to identify the commercial product and explain the role of each number in the documentation. Request that the response be consistent with the current SDS and, where relevant, a composition or identity statement.
Check whether the name on the quotation, package label, SDS, TDS, and COA refers to the same product and grade. Differences can have legitimate explanations, such as a trade name alongside a more general chemical description, but the supplier should be able to explain them. Record the approved product name and identifiers in your purchasing and quality systems to reduce the chance of a substitute being ordered accidentally.
There is no single set of specifications that suits every formulation or application. Ask which attributes are tested for the offered grade, how each test is performed, and whether the COA reports results against a defined limit or range. Depending on your application, your team may need to review characteristics such as appearance, viscosity, solids content, or other supplier-reported properties; do not assume any of these values without product-specific documentation.
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For comparable viscosity results, specify the measurement method, instrument conditions, and temperature in your own requirements. For example, a buyer may request reporting at 25 °C when that condition is appropriate to the method and material. This is a proposed reporting condition, not a claim about the product’s specification or recommended testing procedure; confirm feasibility with the supplier before making it an acceptance requirement.
Ask whether the COA will identify the specific lot supplied and whether the supplier can explain how changes to product identity, manufacturing, or specifications are communicated. As an internal qualification practice, buyers may review 3 representative lots when consistency across batches is important. This is a suggested buyer-side review approach, not a guarantee of performance or a universal industry requirement.
Confirm that the material’s stated purpose and available documentation fit your intended cosmetic application. Review relevant safety, handling, storage, and regulatory information with your internal specialists for each destination market. A supplier document can support your assessment, but it does not replace your responsibility to evaluate the finished product and its intended use.
Request a quotation that identifies the exact product and grade, package size, minimum order quantity (MOQ), price basis, shipping terms, and estimated lead time. Clarify whether the quoted material will be supplied with the same documentation reviewed during qualification. If a sample is available, agree on its identity and documentation before using it in laboratory work.
For document control, buyers may choose to re-confirm critical supplier statements at least every 12 months, or sooner when a product, specification, or market requirement changes. This is a practical review interval to consider, not a fixed regulatory rule. Your organization should set the interval based on risk, purchasing frequency, and its quality procedures.
A frequent mistake is treating a matching CAS number as proof that products from different suppliers have identical composition, quality, or performance. Another is approving an SDS while leaving the TDS, COA, or product label unchecked. Buyers should also avoid copying a supplier’s typical value into an internal specification unless the test method, unit, acceptance range, and application rationale have been reviewed.
Do not assume that a cosmetic-use description establishes suitability for every formulation, market, or finished product. If a supplier cannot answer a question about identity or provide a document needed for your review, record the gap and request a resolution rather than filling it with an assumption. Keep the final approved specification and the supporting documents together for future purchasing and incoming quality checks.
When contacting NKY Group, share the intended application, destination market, required documentation, and the exact CAS identifiers shown in your inquiry. We can help clarify the product information available for review and discuss the documentation, specification points, sample needs, packaging, and supply terms relevant to your project. Any identity or specification confirmation should be based on the current product documents and confirmed directly for the grade being quoted.
To verify a product listed as CAS 28211-18-9; 77035-98-4, first obtain a written explanation of what each identifier represents, then reconcile that explanation with the product label, SDS, TDS, COA, and quotation. Set acceptance criteria around your application and require lot-specific results where relevant, rather than assuming the CAS listing defines the full specification. Your next step is to send the supplier your intended use and document checklist, resolve any identity discrepancies, and approve the material only after your technical and quality teams have reviewed the evidence.
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