Ceramide NP CAS Numbers Explained: How to Resolve 34354-88-6 vs 100403-19-8 Before Buying

Quick Answer

A Ceramide NP listing can look technically complete and still leave the buyer with an identity problem. One supplier writes CAS 100403-19-8, another writes 34354-88-6, a third uses both numbers, and a marketplace title may simply say Ceramide 3 or Ceramide NP powder. The mistake is to treat the first matching CAS as proof that the materials are interchangeable.[1,2]

The more defensible approach is to treat the CAS number as one field in an identity package. The buyer must reconcile the INCI name, chemical description, structure or synonym, molecular-weight basis, source and production route, assay method, physical form and lot COA. If those fields do not tell the same story, the offer is not ready for approval. For the format question that often sits behind this confusion, see the companion guides Powder vs Liquid and Ceramide NP or a Ceramide Complex?.

For procurement, the pass condition is not that the CAS looks familiar. It is that the supplier explains the CAS used for the exact grade, the INCI and chemical identity match the intended material, the COA belongs to the same lot, and the assay method supports the stated purity. A conflicting CAS is a clarification gate; an unexplained CAS conflict is a stop gate.

Why Two CAS Numbers Can Appear in the Same Sourcing Project

The central distinction is between nomenclature and material qualification. A name can be updated while old documents remain in circulation. A supplier can also use a broad trade label for a mixture. Neither situation is solved by copying a CAS number from a search result into the purchasing specification.

What the Authoritative Records Actually Establish

PubChem's Ceramide 3 record exposes CAS 34354-88-6 and describes the compound with synonyms including N-stearoyl phytoceramide and Cer[NP]. Separate PubChem and regulatory records expose Ceramide NP under CAS 100403-19-8. The European Commission CosIng record defines Ceramide NP by its structural description rather than by a marketing grade. CIR's safety assessment explains that former Ceramide 3 naming is retained as a retired monograph, while Ceramide NP is the current ingredient assignment in the reviewed nomenclature.[1,2,3,4]

These sources support a careful conclusion: a CAS discrepancy can arise from naming and registry history, but the buyer still needs the supplier's grade-specific explanation. The public record does not authorize a universal rule that every product carrying either number is equivalent. A powder, an extract, a pre-dispersion and a multi-ceramide complex can share words in the title while requiring different specifications.

The Identity Package That Should Accompany a Ceramide NP Offer

Ask the supplier to place the following fields on one controlled specification, or to cross-reference them clearly across the TDS, SDS, product label and batch COA:

• INCI name and product name, including whether the material is pure Ceramide NP, a complex or a carrier-based dispersion.
• The CAS number used for the exact grade, plus an explanation if the supplier lists 34354-88-6, 100403-19-8, 178436-06-1 or another number.
• Chemical name, synonym and structural description; for a pure grade, the supplier should identify the relevant sphingoid base and fatty-acid chain rather than only saying ceramide.
• Molecular formula and molecular-weight basis, with a note if the commercial material contains water, carrier, salt, lipid or extract matrix.
• Source and production route: synthetic, fermentation-derived, rice or konjac extract, or another declared route. Source does not replace chemical identity.
• Assay method, reference standard, calculation basis, and whether the reported result is Ceramide NP, total ceramides or an extract marker.
• Physical form, particle-size information, moisture or loss on drying, insoluble matter, melting range where applicable, residual solvents, heavy metals and microbiological limits.
• Lot number, production date, retest or expiry basis, storage conditions, and a match between the sample, COA and commercial SKU.

If the supplier cannot explain the CAS conflict but can provide a complete identity and lot-document package, keep the offer in a clarification pool. If the supplier cannot provide both the identity explanation and lot-level analytical evidence, do not call the material production-qualified.

CAS Matching Is Not the Same as Assay Matching

Two offers can carry the same CAS number and still differ in assay method, impurity profile and active basis. A percentage in a title may be an HPLC area result, a dry-basis assay, a total-ceramide figure or a supplier-defined complex value. The buyer should read the assay field in the COA together with its method, its basis and its acceptance range before comparing two quotations.

Physical state belongs in the same review. Ceramide NP is a poorly water-dispersible lipid, so the formulation route may require a suitable heated lipid phase, an emulsifier system or a pre-dispersed delivery format. A supplier's oil soluble or water soluble phrase does not by itself define the physical state of the commercial material.[5,6]

• Confirm the phase and temperature used in the supplier's solubility or dispersion test.
• Ask whether the final result was a clear solution, a translucent dispersion, a suspension, or temporary disappearance under shear.
• Test the exact lot in the intended formula and package; do not transfer a branded supplier's process window to a generic listing.
• Inspect for haze, sediment, crystals and viscosity drift after cooling and accelerated storage.

A Practical Resolution Workflow

1. Freeze the material identity you actually need: pure Ceramide NP powder, a standardized plant-derived material, a water-dispersible format, or a multi-ceramide complex.
2. Record every CAS, INCI, synonym and product code shown in the supplier's current documents. Do not delete the conflict from the comparison sheet.
3. Ask the supplier to explain the CAS mapping for the exact grade, and to state whether the number belongs to the pure molecule, legacy nomenclature or a commercial complex.
4. Require a current lot COA and compare its product name, lot number, method, result and specification with the sample label and quotation.
5. Check the assay basis and carrier load. Recalculate the delivered Ceramide NP amount only after the percentage has been analytically defined.
6. Run identity and physical-form checks in the intended formulation. If the supplier says water soluble but the material is a dispersion, record the distinction and evaluate its stability.
7. Approve the lot only when the identity package, analytical result, physical behaviour and change-control expectation are aligned.

RFQ Questions Worth Sending

• Which CAS number applies to the exact product code and shipped grade, and why are other CAS numbers shown in your catalogue?
• Is the current INCI Ceramide NP? Is the product pure Ceramide NP, legacy Ceramide 3 material, a ceramide complex or a carrier-based dispersion?
• What does the stated percentage measure, and what analytical method and reference standard support it?
• Does the COA report Ceramide NP specifically, total ceramides or an extract marker?
• Please provide the full INCI and carrier composition for any water-dispersible, liposomal or 50% product.
• Can you match the sample, COA, TDS, SDS, product code, lot number and commercial quotation?
• What changes require customer notification if the production route, source, CAS mapping, carrier or assay method changes?

A Current Sourcing Lead

The offer below is a sourcing lead, not a supplier ranking. The product link was confirmed to land on the Product ID shown. It has visible sales activity and a clearly stated Ceramide NP format, while its supplier-age evidence contains a conflict that should stay visible rather than being silently resolved.

A product listing and a supplier storefront are different routes and are not interchangeable.

When the Offer Should Be Paused

Pause the offer when the supplier uses Ceramide NP, Ceramide 3, Ceramide III, phytoceramide and ceramide complex as if they were automatic synonyms. Pause it when two CAS numbers are listed with no grade-specific explanation, when the percentage has no method, or when the COA belongs to a different product code. Pause it when the supplier calls a carrier-based powder 99% pure Ceramide NP without stating whether the number is a marker or a molecule-specific assay.

Supplier age remains a weighted screening signal. A platform-age conflict is not automatically a rejection, but it increases the need for current factory identity, traceable documents, repeat-lot evidence and a clear change-control process. Do not upgrade an unresolved commercial contradiction into a claim of factory-direct reliability.

Bottom Line

The question is not whether Ceramide NP has one universally accepted number printed beside it. The question is whether the supplier can prove what its number means for the exact material being sold. CAS 34354-88-6 and 100403-19-8 should trigger reconciliation, not automatic acceptance or automatic rejection.

For a cosmetic buyer, the safest decision record contains the current INCI, the supplier's CAS explanation, the grade-specific identity and assay method, the physical format, the lot COA and the formulation trial. If those pieces agree, a legacy versus current naming difference may be manageable. If they do not, the cheaper offer is not a bargain; it is an unresolved identity risk.

References

1. PubChem. Ceramide 3, CID 9898642. CAS 34354-88-6 and compound identity record. https://pubchem.ncbi.nlm.nih.gov/compound/Ceramide-3
2. PubChem. Ceramide NP / N-stearoyl phytosphingosine record. CAS 100403-19-8. https://pubchem.ncbi.nlm.nih.gov/compound/Ceramide-NP
3. European Commission. CosIng: CERAMIDE NP ingredient record. https://ec.europa.eu/growth/tools-databases/cosing/details/92555
4. Burnett CL, et al. Safety Assessment of Ceramides as Used in Cosmetics. International Journal of Toxicology. 2020. https://journals.sagepub.com/doi/full/10.1177/1091581820958692
5. Bektay HS, et al. The Design and Optimization of Ceramide NP-Loaded Liposomes to Restore the Skin Barrier. Pharmaceutics. 2023. https://pubmed.ncbi.nlm.nih.gov/38140026/
6. Zhou H, et al. Current Advances of Nanocarrier Technology-Based Active Ingredient Delivery in Cosmetics. 2021. https://pmc.ncbi.nlm.nih.gov/articles/PMC8286087/
7. Lim SH, et al. A Lipid Mixture Enriched by Ceramide NP with Fatty Acids of Diverse Chain Lengths Contributes to Restore the Skin Barrier Impaired by Topical Corticosteroid. Skin Pharmacology and Physiology. 2022. https://pubmed.ncbi.nlm.nih.gov/34348350/
8. Coderch L, et al. Ceramides and skin function. American Journal of Clinical Dermatology. 2003. https://pubmed.ncbi.nlm.nih.gov/12553851/