The determination of diacetyl, 2,3-pentanedione and acetoin was performed in two steps. Diacetyl and 2.3-pentanedione were driven off with gaseous nitrogen at 60 degrees C and collected in ice cooled methanol. The quantitative gaschromatographical determination follows after directly injecting this solution into the gas chromatograph employing an electron capture detector which indicates selectively the vicinale diketones. In a second experiment acetoin was determined by a differential method after oxidizing acetoin to diacetyl. The investigation of 57 German white wines of various vintages, varieties and quality classes yielded the following results: Diacetyl: Limits of variability (V) = 0.08-3.40 mg/l, average amount (M) = 0.42 mg/l; 2.3-pentanedione: V = 0.02-0.36 mg/l, M = 0.10 mg/l; Acetoin: V = 1.9-31.7 mg/l, M = 5.9 mg/l. No differences could be observed with regard to the various quality classes. In 20 red vines of various European origines the following amounts were observed: Diacetyl: V = 0.26-4.06 mg/l, M = 1.46 mg/l; 2.3-pentanedione: V = 0.08-0.88 mg/l, M = 0.25 mg/l; Acetoin: V = 5.9-38.2 mg/l, M = 15.0 mg/l. For a rule the red wines show considerable higher contents of diacetyl, 2.3-pentanedione and acetoin than the white wines.
