Abstract
The content of methanol in cosmetics must be less than 0.2%, and it has been usually analysed by chromotropic acid colorimetry. This method, however, was not always satisfactory owing to the interference of perfumes, surface-active agents, and others in cosmetics. The modified procedure has been developed as follows : 20 ml of water was added to 5 ml of a sample and distilled, 10 ml of the distillate was transferred to a separatory funnel, shaken with 5 ml of petroleum benzine, and K2CO3 was added to the aqueous layer to seperate alcohol. Alcohol layer was made up to 5 ml with ethanol, diluted to 50 ml with water, 0.5 g of active carbon was added, and the filtrate was applied to the colorimetry procedure. Heating time and temperature in the color reaction were corrected to 40 min and 100°. Good reproducibility was obtained by this method.
