DEVELOPMENT OF CLOUD POINT EXTRACTION-SCANOMETRY, FOR THE PRECONCENTRATION AND DETERMINATION OF COLORLESS SPECIES: APPLICATION FOR THE DETERMINATION OF PHENYLALANINE
In this study, a simple, fast, portable, environment-friendly and inexpensive method, CPE-scanometry, is applied for the determination of Phenylalanine (Phe) amino acid. The extraction of analytes from water samples (15 ml) was performed in the presence of Triton X-114 as a non-ionic surfactant in a water bath environment, diluting the extracted surfactant-rich phase with alkali ethanol as a suitable solvent to 0.5 mL and transferring an appropriate volume to a special cell. The individually cylindrical cavities in the sheet of Plexiglas serve as reaction chambers. These cylindrical cavities in the sheet of Plexiglas are fabricated with a laser beam. The cells containing the analyte solution were scanned with a scanner, then the color of each cell was analyzed, by software written in Visual Basic (VB 6), to obtain the red, green and blue values. The influence of operation parameters including pH, concentrations of surfactant and electrolyte on the cloud point extraction of analyte were studied and optimum conditions were established. Under optimum condition, limit of detection (LOD), relative standard deviation (RSD) and linear range for the proposed method are obtained 0.06, 3.42 and 0.2-10.0 mg L-1 respectively. Finally, the proposed method was utilized successfully for the determination of Phenylalanine in some water and waste water samples in recoveries range 94.1–107.7%.