Solid-Phase Extraction of Antipyrine Dye for Spectrophotometric Determination of Phenolic Compounds in Water

In order to determine phenolic compounds in water, we propose a method based on the reaction of phenolic compounds with 4-aminoantipyrine in the presence of peroxodisulfate at pH 10 to form antipyrine dye and the solid-phase extraction of dye with a Varian Bond Elut Plexa cartridge. Dye collected on the cartridge is eluted with acetonitrile and the absorbance is measured at 475 nm. In our experiments, recovery ratios of >90% were obtained for phenol, o-aminophenol, m-aminophenol, o-methoxyphenol, m-methoxyphenol, p-methoxyphenol, o-cresol, m-cresol, o-chlorophenol, m-chlorophenol, p-chlorophenol, 2,5-dimethylphenol, and 2,4-dichlorophenol. The calibration curve obeyed Beer's law in the range 0 - 0.30 mu g ml(-1) phenol. The precision of repeated tests (n = 4) was 1.7% of the phenol solution (0.10 mu g ml(-1)); the detection limit was 0.0011 mu g ml(-1). Recovery tests using river water, waste water, and sewage influent gave highly satisfactory results.