A new spectrophotometric method for the detection and determination of keto sugars and trioses.

To 1.0 cc. of a solution containing 1 to 50 y of a ketohexose, either in free form or in the form of its esters or polymers, or 2 y of triose or glycolic aldehyde, is added 0.2 cc. of a 1.50 per cent solution of cysteine hydrochloride. To this 6 cc. of a mixture of 190 cc. of water and 450 cc. of concentrated sulfuric acid, c.p., are added and immediately afterwards 0.2 cc. of a 0.12 per cent alcoholic solution of carbazole. The mixture is shaken and left standing at room temperature.