By I Am Chemicals Team

If you make washing powder, dishwashing liquid or household cleaners, you almost certainly buy LABSA: linear alkylbenzene sulphonic acid, often sold as "sulphonic acid 96%". The HERA risk assessment of LAS (revised April 2013, still the main published industry assessment) describes LAS as one of the major anionic surfactants on the market. Here is what buyers and formulators should know.

What LABSA is

LABSA is the acid form of linear alkylbenzene sulphonate (LAS), an anionic surfactant. According to the HERA risk assessment of LAS, it was introduced in 1964 as the readily biodegradable replacement for the highly branched alkylbenzene sulphonates used before. Commercial LAS is not a single molecule. It is a mixture of closely related compounds with a linear alkyl chain of typically 10 to 13 carbon atoms attached to a sulphonated benzene ring.

LABSA has its own six-digit tariff subheading: 3402.31 ("linear alkylbenzene sulphonic acids and their salts"). In the current South African tariff (Schedule 1, Part 1) this is split into 3402.31.10 for immediate packings of 10 kg or less and 3402.31.20 for larger packings. Always check the current SARS tariff before you declare.

How it is made

HERA describes a two-step chain:

• LAB (linear alkylbenzene) is made by alkylating benzene with linear mono-olefins or chloro-paraffins.
• LAB is then sulphonated. The first commercial processes used oleum or sulphuric acid; today's state of the art is SO₃ gas in falling-film reactors. The product is the brown, viscous acid sold as LABSA.

Where it goes in a detergent

LABSA is not used as the free acid in the finished product. Detergent makers neutralise it, most commonly with caustic soda, to form sodium LAS; in powders it is neutralised with alkaline builders during processing. HERA lists the main applications as laundry powders, laundry liquids, dishwashing products and all-purpose cleaners.

Formulators use LAS because it cleans and foams well, is cost-effective and combines easily with other surfactants (such as SLES or non-ionics) and builders. Water hardness affects performance, so test the full formula with the water your customers actually use.

Practical formulation points:

• Neutralising LABSA with caustic soda releases heat. Add it gradually with good stirring, control the batch temperature, and follow the mixing and dilution guidance in your supplier's SDS.
• Check the pH of the neutralised batch against your target range before adding perfume, colour or preservative.
• Record the active content of each LABSA batch. Your caustic dosage and final active level depend on it.

What to check on the Certificate of Analysis

LABSA is sold by specification, so compare CoAs batch by batch against your supplier's specification sheet. The parameters usually reported are:

• Active matter: the value your formula depends on. A "96%" grade is specified at a minimum of 96%.
• Free sulphuric acid (inorganic acid): adds to the caustic needed for neutralisation and ends up as sodium sulphate in the product. Typical 96% grade specifications set a low maximum (often around 1.5%); use the figure on your supplier's specification sheet.
• Free oil (unsulphonated matter): material that adds no surfactant activity. Typical specifications set a maximum of around 2%; check your supplier's sheet.
• Colour: usually measured in Klett units on a 5% solution; important for clear or light-coloured liquids.
• Water content: commonly about 1% maximum.

Ask for a CoA and SDS with each delivery, and check that both refer to the same product name and batch.

Handling, storage and transport

LABSA is a strong acid and corrosive to skin and eyes. Follow your supplier's SDS for:

• personal protective equipment (chemical goggles or a face shield, acid-resistant gloves and clothing);
• suitable tank, pump and hose materials, and storage temperature;
• spill control and first aid.

For transport, LABSA with not more than 5% free sulphuric acid is listed under UN 2586 (alkylsulphonic or arylsulphonic acids, liquid), Class 8 (corrosive), Packing Group III, in the UN dangerous goods list and in ADR (ADR 2025; the ADR 2027 amendments apply from 1 January 2027, and ADR 2025 may still be used until 30 June 2027). Always take the UN number and packing group from section 14 of your supplier's SDS, because classification depends on the exact composition. In South Africa, road transport of dangerous goods falls under Chapter VIII of the National Road Traffic Regulations, which incorporate SANS 10228 and related SANS dangerous goods standards, so loads need the correct documentation and a compliant carrier. For the paperwork when chemicals leave South Africa, see our export documents checklist.

Environmental profile

The HERA assessment concludes that LAS is readily and ultimately biodegradable under aerobic conditions, for example in activated-sludge wastewater treatment. It does not degrade under anaerobic conditions (for example in sludge digesters), except in particular circumstances; the OECD SIDS assessment reaches similar conclusions. Proper wastewater treatment is therefore an important part of using LAS responsibly.

What to compare when buying LABSA

When you compare offers, look beyond the price per tonne:

• the active content you are actually paying for;
• packaging: drums, IBCs or bulk road tankers, and whether your site can offload them safely;
• lead time and consistency from batch to batch;
• documentation: a CoA and SDS for every batch, and the correct HS code on the invoice.

I Am Chemicals is a South African-based supplier of industrial and speciality raw materials. For a specification or a quote, email adele@iamchemicals.co.za or call +27 74 524 8671.

General information only. Always follow your supplier's SDS and your own formulation testing.

Sources

• HERA – Human & Environmental Risk Assessment on ingredients of household cleaning products: Linear Alkylbenzene Sulphonate (LAS), revised April 2013: https://www.heraproject.com/wp-content/uploads/2025/08/HERA-LAS-revised-April-2013-Final1.pdf
• OECD SIDS Initial Assessment Report – Linear Alkylbenzene Sulfonate (LAS), via the American Cleaning Institute: https://www.cleaninginstitute.org/sites/default/files/research-pdfs/LAS_SIAR.pdf
• SARS – Customs & Excise Tariff, Schedule 1 Part 1, subheading 3402.31: https://www.sars.gov.za/wp-content/uploads/Legal/SCEA1964/Legal-LPrim-CE-Sch1P1Chpt1-to-99-Schedule-No-1-Part-1-Chapters-1-to-99.pdf
• UNECE – ADR 2025 (and ADR 2027 status), Agreement concerning the International Carriage of Dangerous Goods by Road (Table A, UN 2586): https://unece.org/adr-2025-files
• National Road Traffic Regulations, regulation 273A – incorporation of SANS standards for dangerous goods: https://www.acts.co.za/national-road-tra/r225_273a__incorporation_of_st