Separation of diacetyl, acetoin, and 2,3-butylene glycol by salting-out chromatography

Salting-out chromatography was found suitable for separating microgram quantities of diacetyl, acetoin, and 2,3-butylene glycol at room temperature. One milliliter of a solution containing 25 to 100 μg of each of the compounds to be separated is applied to the top of a column of Dowex 1-X8 anion-exchange resin in the sulfate form. The compounds are separated and eluted from a 1.9 × 27 cm column with 0.5 M (NH 4) 2SO 4 at a flow rate of 0.5 ml/min, or from a 3.5 × 54 cm column with 0.5 M Na 2SO 4 at a flow rate of 1.5 ml/min. The compounds emerge from the columns quantitatively in decreasing order of polarity: 2,3-butylene glycol, acetoin, and diacetyl. The separated 2,3-butylene glycol is oxidized to acetoin with bromine water. With the compounds separated and the glycol converted to acetoin, the Westerfeld method can be used to complete the quantitative determinations.