Detection of carbohydrates
Approximately 2 mg of methanolic extract was shaken with 10ml of water
in attest tube, filtered and the filtrate was concentrated. To the
filtrate 2 drops of freshly prepared 20% alcoholic solution of α-
naphthol was added. 2 ml of conc. sulphuric acid was added so as to form
a layer below the mixture. Red-violet ring appeared, indicating the
presence of carbohydrates which disappeared on the addition of excess of
alkali.