AOAC Official Method 942.06 Alcohol by Volume in Distilled Liquors
Pycnometer MethodFirst Action 1942
Final Action
A. Apparatus
Distillation apparatus.—500 mL flask, connected through bulb to vertically assembled Liebig condenser with jacket ³400mmlong,inner tube 9 ± 1 mm id, with adapter. Joints may be live rubber or standard taper. Heat with electric- or gas-operated unit.
B. Determination
(Some distilled liquors do not require distillation prior to determination,e.g., straight bourbon whisky; alcohol–H2O mixtures containing traces of volatile ingredients.)
(a) Test samples containing 60% or less alcohol by volume.—Calibrate 100 mL pycnometer, Figure 942.06, as in 945.06B (see 26.1.06), at one of temperatures specified in 913.02 (see Appendix
C). Fill clean, dry pycnometer with test portion and adjust to volume at calibration temperature as in 945.06B (see 26.1.06).Transfer contents of pycnometer to distilling flask, just previously rinsed with cold H2O and containing few glass beads, or equivalent.Rinse pycnometer 3 times, using total of 25 mL cold H2O (40 mL for cordials or wines), and add rinse H2O to flask. Place wet pycnometer so that adapter extends just into bulb. Surround pycnometer with ice or ice H2O. Complete connections and pass through condenser rapid stream of H2O kept at £25°C at outlet. Distil ca 96 mL at uniform rate in ³30 but £60 min, using longer times for higher percentages of alcohol.
Remove and stopper pycnometer, mix distillate by swirling, and wash down with H2O any drops that may be above graduation mark. Immerse in constant temperature bath at calibration temperature and after 30 min carefully dilute to volume, with aid of capillary tube, by addingH2Opreviously boiled and cooled to same temperature. Determine specific gravity of distillate as in 945.06C (see 26.1.06). Obtain corresponding % alcohol by volume from 913.02 (see Appendix C). (This result is % alcohol by volume at 15.56°C [60°F].)
