Dissolve 15 grams of the acetaldol in distilled water and dilute to 1 liter in a volumetric flask. Transfer 5 mL of this solution to a 250 mL glass-stoppered flask containing 25 mL distilled water. Add 25 mL of a freshly prepared 1 percent sodium bisulfite solution. Prepare a blank omitting the acetaldol solution. Place the flasks in a dark place away from excessive heat or cold and allow to stand six hours. Remove flasks and titrate free bisulfite with 0.1 N iodine solution using starch indicator.

Percent acetaldol by weight = (mL blank − mL test) × 200 × 0.44 / weight of sample

Titrations in excess of 100 percent may be obtained if the sample contains appreciable amounts of acetaldehyde.