抄録
A singly charged tetrabromophenolphthalein ethyl ester (TBPE) anion was found to be extracted with alkaloids as 1 : 1 complexes in 1, 2-dichloroethane. Of various solvents, TBPE-1, 2-dichloroethane system gave a red color for alkaloids, while in the absence of alkaloids, an organic phase shows a pale yellow color. In this way, the spectrophotometric methods were investigated for the determination of a small amount of the alkaloids, such as quinine, emethine and ephedrine, by solvent extraction. Quinine is determined by measuring the absorbance of the extracts over a range from 0.5-5×10-6M (0.20-1.98 μg/ml) at 555 nm. Emethine is determined from 2×10-6M to 1×10-5M (1.1-5.5 μg/ml) at 570 nm and ephedrine, from 1×10-6M to 1×10-5M (0.20-2.0 μg/ml) at 555 nm. From the conductivity measurements, it is concluded that red species in the extract is considered to be a kind of charge transfer complexes.
