Short answer: Yes — SLS is a sulfate (a sulfate ester), so it is excluded from any sulfate-free claim, as is SLES. The common sulfate-free replacement is AOS.
The chemistry behind the claim
- Sulfate ester: SLS and SLES carry a C-O-S linkage. Products marketed as sulfate-free typically exclude alkyl sulfates and alkyl ether sulfates.
- Sulfonate: AOS (sodium C14-16 olefin sulfonate, CAS 68439-57-6) carries a direct C-S bond and no sulfate ester group, which is why it appears in many sulfate-free shampoos, body washes and dish liquids.
What to do if you need a sulfate-free formula
Start from AOS CAS 68439-57-6 — typically the 35% or 38% liquid grade for personal care liquids and 92% or 95% powder for detergent formats. Expect to rework your thickening system, because salt responds differently in sulfonate systems than in SLES-based ones. See the AOS buyer’s guide for grade selection and our detergent selection guide for formulation trade-offs. Confirm the final claim wording with your regulatory or marketing team, since retailer requirements differ by market.