What is the difference between SLS and SDS?

Short answer: SLS and SDS are the same molecule — sodium dodecyl sulfate, CAS 151-21-3. Only the name changes with the industry.

Detergent, personal care and oral care buyers normally use sodium lauryl sulfate (SLS), and you will also see the trade name K12. Laboratory, electrophoresis and life-science buyers use sodium dodecyl sulfate (SDS). Both names describe the same C12 alkyl sulfate, so they share one CAS number.

• Same CAS: 151-21-3 for all commercial grades.
• Same chemistry: a sulfate ester of lauryl (C12) alcohol, neutralised with sodium.
• Different grades: 92-95% powder and needles for detergents, 30% liquid, and high-purity 97-99% grades for laboratory and pharmaceutical use.

Practical consequence for buyers: when you write an enquiry, give the CAS number and the grade, not just the name. See SLS CAS 151-21-3 for industrial grades and SDS CAS 151-21-3 for high-purity grades. If you are buying for protein electrophoresis, read how to choose electrophoresis-grade SDS — there the purity specification, not the name, is what matters.