Abstract
A fluorophotometric method with tetrabromofluorescein ethylester (TBFE) has been proposed for the determination of quaternary ammonium salt. Fluorescent TBFE was synthesized by esterification of tetrabromofluorescein. Various conditions were examined to determine the optimal condition. The proposed method are as follows. Determination of tetraethyl-ammonium bromide; To a 20 ml test tube are added 1 ml of tetraethylammonium bromide solution of a concentration ranging between 0.5 and 5.0 μg/ml, 2.5 ml of borate buffer (pH 10), 0.2 ml of TBFE ethanolic solution (250 μg/ml) and 5.0 ml of 1, 2-dichloroethane.
In order to ensure complete extraction of TBFE tetraethylammonium complex, the mixture is throughly stirred for 1 min. After being allowed to stand for a few minutes, the aqueous phase is removed. About 4 ml of the 1, 2-dichloroethane phase is transferred to the cell. The fluorescence intensity is measured at its excitation (542 nm) and emission (562 nm) maxima. The reagent blank is run through the whole procedure.
Interference of ascorbinic acid, several amino acids, antipyrine, creatin, thiamin, urea, uric acid and glucose was examined. Most of them caused no effect on the results. The sensitivity of the proposed method is about 100 times that of the usual colorimetric method using acid dye.
