Abstract
A sensitive solid-phase spectrophotometric method for the determination of phenol in tap water or river water samples was developed. The antipyrine dye formed by the reaction between phenol and 4-aminoantipyrine was extracted and concentrated from 50 cm3 of sample solutions on the finely divided anion-exchange resin in the presence of sodium sulfate (14.5 g/50 cm3 of a sample solution) as the salting out reagent. After the resin was collected on a membrane filter by filtration under suction as a colored circular thin layer (ca. 17 mm in diameter), the absorbance of the antipyrine dye fixed on the resin thin layer was measured directly on the membrane filter. Calibration graphs were prepared in the range 0 - 1.0 μg of phenol. The calibration graphs consist of two linear regions, 0 - 0.6 μg and 0.6 - 1.0 μg. The relative standard deviations were 1.9 and 0.2% for five replicate determinations of a blank and 1.0 μg of phenol, respectively. The detection limit, based on three times the standard deviation of the blank, was 25 ng of phenol for 50 cm3 of solution (0.5 ng cm-3). The recovery test was done by adding a 0.2 or 0.4 μg amount of phenol to 50 cm3 of tap water or river water samples and determining phenol by the proposed method with or without separation by distillation of phenol. The recoveries were 90 - 110% and the relative standard deviations were 1.8 - 15% for the tap water samples analyzed with or without distillation and the river water sample with distillation. On the other hand, recoveries were 110 - 120% for the river water sample analyzed without distillation.
