Abstract: A method for solubilising and separating one or a plurality of carboxylic acids or carboxylic acid derivatives from an aqueous or organic solution, emulsion or suspension, involves (i) preparing the solution or emulsion or suspension with the carboxylic acid or the carboxylic acid derivatives; (ii) adding a quantity of a solubilising compound, in particular arginine or an arginine derivative, to the solution, suspension or emulsion in the presence of a minimum amount of water, a demobilised solubilising compound being used as a solubilising compound; (iii) separating the solubilised carboxylic acids or carboxylic acid derivatives as a carboxylic acid phase or carboxylic acid derivative phase from the solution or emulsion or suspension; and (iv) preferably regaining at least one portion of the solubilising compound or one portion of a derivative of the solubilising compound, in particular of the arginine or the arginine derivative, from the solubilised and separated carboxylic acid phase or carboxylic acid der