PRINCIPLE:

 

             The automatic method of analysis is based on the known property of cationic surfactants (quaternary ammonium salts) to react with the anion dye Blue of Disulfina, forming a colored complex soluble in organic solvent. Since free Disulfin Blue is insoluble in organic solvent, the amount of colour extracted from the organic phase is proportional to the amount of cationic surfactant present in the sample.

Photometric reading of the organic phase is performed at 628 nm