preconcentration

The extraction of the tungsten blue complex formed by the reaction of phenol with Folin-Ciocalteu reagent (FCR) in the presence of a nonionic surfactant Triton X-100 in alkaline medium using the methodology of micellar extraction based on «clouding point» has been studied for the fi rst time. Aqueous solutions of sodium carbonate and sodium sulfate were used to create pH and as a desalting agent.

Synthetic azodyes are widely used in paint, textile, plastic, and food, beverage, and leather, cosmetic, pharmaceutical and paper industries to make products more visually attractive to consumers. Therefore, they are also the components of waste waters and should be removed due to their potential risk to human health. Many techniques have been employed to eliminate dyes from waste water and do to preconcen- tration before analysis in food or beverage objects.

For the efficient preconcentration of azo compounds – products of the interaction of 4-nitrophenyldiazonium with thymol, a system 4-nitroaniline (4-NA) – NO2 - – Triton X-100 – NaOH – ethanol has been proposed. The optimal conditions for the formation of micellarsaturated phases of the system under study have been established: 3. 10-4 M 4-NA – 3. 10-4 M NO2 - – 5% Triton X-100 – 2.8 M NaOH – 10 vol. % С2Н5ОН. A spectrophotometric study of the above system has been carried out.