Separation of carbazole by sulfuric acid extraction followed by spectrofluorometric determination.

Abstract

A liquid-liquid extraction procedure has been developed for separating carbazole from the related polynuclear aromatic compounds. Carbazole was first extracted from the cyclohexane solution into (8485) % sulfuric acid, and then back-extracted into fresh cyclohexane by diluting the sulfuric acid with water. After separation, the subsequent determination was carried out by spectrofluorometry. Carbazole in 20 ml of the sample solution was extracted into 10 ml of sulfuric acid at room temperature. On separating two layers, the sulfuric acid layer was separated from the cyclohexane and poured into 70 ml of water. The cyclohexane layer was washed with 5 ml of sulfuric acid and this sulfuric acid was combined with the preceding one. Then, carbazole was back-extracted into 10 ml of fresh cyclohexane. By this method, (0.580) μg of carbazole in (110) mg of the sample could be separated. The recovery was 97 % with 0.53 % of coefficient of variation. Carbazole could be determined by measuring the relative fluorescence intensity at 345 nm with excitation at 325 nm. As a standard, 1 μg/ml solution of carbazole was used. Incompleteness of the recovery was corrected by using the calibration curve obtained under the identical conditions as the sample. The method was not interfered by the presence of 10 mg of phenanthrene, fluorene, dibenzofuran, and biphenyl, 5 mg of acenaphthene, 1 mg of anthracene and fluoranthene, 0.5 mg of pyrene, 2 μg of anthraquinone and phenanthrenequinone, and 20 μg of 9-fluorenone.