Microextraction preconcentration with nonionic surfactants and colorometric determination of phenol

Abstract

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. The latter, having a desalting eff ect, promotes phase separation in the system under study into a micellar phase saturated with surfactant (Triton X-100) and an aqueous phase depleted in surfactant without additional heating at room temperature. Optimal conditions for micellar phenol extraction were determined: FCR (0,2 n.) – Na2 CO3 (6%) – Triton X-100 (2%) – Na2 SO4 (3,2%). It is shown that micellar-saturated phases of Triton X-100 eff ectively extract the analytical form (tungsten blue complex), can be proposed for extraction-spectrophotometric and colorimetric determination of phenol. So, for the spectrophotometric determination of phenol (λmax= 760 nm), the Beer-Bouguer-Lambert law obeys an equation of the form: y = 0,0007x – 0,0079, R2 = 0,997. The range of defi ned contents is in the interval 7·10-7 – 6·10-5 M. A technique for the colorimetric determination of phenol in aqueous media (channel R) has been developed. The intensity of the chromaticity channel R (IR) linearly depends on pc(phenol) in accordance with the equation: y = 95,0x – 455; R2 = 0,997. The range of defi ned contents is in the interval 7·10-7 – 1·10-5 M. The profi les of the petal diagrams in the RGB CMYK color coordinates are constructed, the dependences of their area are obtained (S) and perimeter (P) from -lgc : (perimeter (P) y = 150x – 284; R2 = 0,994; area (S) y = 17710x – 66930; R2 = 0,994).

Keywords

• phenol
• preconcentration
• surfactants
• micellar extraction
• colorometry
• folin – ciocalteu reagent