Glycerol and other polyols
To 0.20 g of the sample in a round-bottom flask, add 10 ml of ethanolic potassium hydroxide TS, attach a reflux condenser to the flask and heat in
a water bath for 30 min. Add 50 ml of dilute sulfuric acid TS, cool and filter. Rinse the flask and filter with dilute sulfuric acid TS. Combine the filtrate and washings and dilute to 100.0 ml with dilute sulfuric acid TS. Place 1.0 ml of the solution in a tube, add 0.5 ml of a 1.07 % (w/v) solution of sodium periodate, mix and allow to stand for 5 min. Add 1.0 ml of decolourized fuchsin solution (see below) and mix. Any precipitate disappears. Place the tube in a beaker containing water at 40o. Allow to cool while observing for 10 to 15 min. Any bluish-violet colour in the solution is not more intense than a standard prepared at the same time in the same manner using 1.0 ml of a 0.001 % (w/v) solution of glycerol in dilute sulfuric acid TS.