Surfactants sodium lauryl sulfate incompatibility

Organic sulfates Cationic Sodium lauryl sulfate o/w Efficient below pH 7 incompatible with anionic surfactants and polyvalent anions... 

The selection of the surfactant is mainly based on the compatibility with the active substance. Sodium lauryl sulfate is an anionic surfactant and therefore incompatible with cationic active substances. Cetomacrogol emulsifying wax BP is incompatible with high concentrations of phenolic substances due to an interaction of the phenolic group with the polyethylene glycol chains in the macrogol cetostearyl ether. It is compatible with acids, high concentrations of electrolytes and cations. 

A known incompatibility by charge differences is the reaction of anionic surfactants with cations. Sodium cetostearyl sulfate (as compotmd of emulsifying cetostearyl alcohol type A, also known as Lanette N) and sodium lauryl sulfate (as compotmd of emulsifying cetostearyl alcohol type B, also known as Lanette SX) may cause this incompatibility. As a result the lipophilic and hydrophilic phases separate and the cream becomes almost fluid. An example of this effect is the incorporation of chlorhexidine gluconate in lanette creams. The anionic part of the emulsifier precipitates with the chlorhexidine gluconate, which not only decreases the physical stability of the cream but also the effectiveness of chlorhexidine. 

The surfactant most commonly used is the anionic detergent sodium lauryl sulfate. Other surfactants that have been used include sodium dodecylbenzene sulfonate [25155-30-0], sodium A-lauroyl sarcosinate or Gardol [137-16-6], and sodium cocomo-noglyceride sulfonate [3694-90-4]. Cationic and nonionic surfactants are not used for several reasons, including incompatibility with the abrasive system and lack of high foaming capability. 

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