ABSTRACT

A spectrophotometric method was developed for the determination of phenol, catechol and resorcinol. The method based on the reaction of diazonium salt with diazotized benzene as a reagent in the alkaline medium. The products show the maximum absorption at 456, 359 and 497 nm for phenol, catechol and resorcinol respectively. The method showed linearity over concentration ranging between (0.25-15), (0.25-5) and (0.25-7.5) µg/ml for the mentioned compounds, respectively, The molar absorptivity value were 1.26×104, 3.72×104 and 2.86×104 L .mol -1.cm-1 respectively. The limit of detection (LOD) were 0.0963, 0.0430 and 0.0496 µg/ml, and the limit of quantitation (LOQ) were 0.3211, 0.1440 and 0.1655 µg/ml for phenol, catechol and resorcinol. The accuracy ranged between 99.58% -100.41% with a relative standard deviation ≤ 0.38 for all compounds It was found that these compounds formed a color product with benzidine at a ratio of 1:2. The rate constant of stability was 4.29 × 1011, 4.28 × 1010 and 8.74 × 1010 liters 2.mol-2 for the products phenol, catechol and resorcinol respectively. This indicates the good stability of these products.