Spectrophotometric Determination of Trace Phenol in Water After Preconcentration on an Organic Solvent-Soluble Membrane Filter

Abstract

A simple and rapid preconcentration technique based on collecting trace phenol on a membrane filter and dissolving the membrane filter in an organic solvent has been proposed and applied to the spectrophotometric 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 μm nitrocellulose filter as an ion associate of the dye with a cation surfactant. The ion associate along with the filter is dissolved in a small volume of 2-methoxyethanol and the absorbance of the resulting solution is measured at 480 nm against a reagent blank. Beer's law is obeyed over the range 1.25 - 30 μg of phenol in 5 ml of solvent and the detection limit (three times the standard deviation of the blank) is 2.0 μg 1−1 as phenol. The components normally present in water do not interfere in the presence of proper masking agents. The proposed method has been applied to the analysis of water samples from several sources. The recoveries of the phenol added to the samples are quantitative, and results found are satisfactory.