Spectrophotometric Determination of Ethanol in Wine

Abstract

A variation of the micro-dichromate method for the determination of ethanol in wine was devised. Reproducible pipetting of a 1-ml sample was achieved through the use of an automatic diluter. Distillation of the sample into an acidic potassium dichromate solution in a 50-ml volumetric flask permitted simple dilution to volume after heating 20 minutes at 60° C. Percent alcohol by volume was then determined from a direct digital concentration spectrophotometer af 600 mµ after standardization with a known ethanol-water mixture, similarly distilled and reacted. The method eliminates the need for a standard ferrous ammonium sulfate solution as a titrant and the normal indicator solution as well as the difficulties encountered with a 1-ml volumetric pipette.