SPECTROPHOTOMETRIC DETERMINATION OF TRACE PHENOL IN WATER AFTER PRECONCENTRATION ON AN ORGANIC SOLVENT-SOLUBLE MEMBRANE-FILTER

A simple and rapid preconcentration technique based on collecting trac e phenol on a membrane filter and dissolving the membrane filter in an organic solvent has been proposed and applied to the spectrophotometr ic determination of phenol in water. At pH 9.0 phenolic compounds form dyes with 4-aminoantipyrine in the presence of potassium ferricyanide . The product is collected on a 0.45 mu m nitrocellulose filter as an ion associate of the dye with a cation surfactant. The ion associate a long with the filter is dissolved in a small volume of 2-methoxyethano l and the absorbance of the resulting solution is measured at 480 nm a gainst a reagent blank. Beer's law is obeyed over the range 1.25 - 30 mu g of phenol in 5 ml of solvent.