MODIFICATIONS IN THE PHENOLPHTHALEIN METHOD FOR SPECTROPHOTOMETRIC ESTIMATION OF BETA-CYCLODEXTRIN

The phenolphthalein solution used in the assay of beta-Cyclodextrin is not stable and undergoes spontaneous decolorization. There is linear decrease in absorbance of phenolphthalein with time. This causes a continuous increase in error with time which is as high as 80% after one hour. A simple procedure is described in the paper to circumvent this problem allowing reproducible and reliable results to be obtained. A single reagent assay was developed by incorporating phenolphthalein in Na2CO3 solution. This resulted in stable absorbance readings and increased the linearity of assay up to 200 mu g/ml of beta-cyclodextrin.