"Absinthe Myths Finally Laid To Rest" was an interesting read, but those of us at Amalgamated Brewing disagree with the once-and-for-all evidence claimed by Dirk W. Lachenmeier (C&EN, May 5, page 42). Absinthe, like any alcoholic beverage, is a living, dynamic moiety and cannot be assumed to go unchanged during many years of storage. To the contrary, the complex mixture of volatile components in the "green fairy" makes this beverage particularly susceptible to chemical and physical changes.
Thujone is fairly volatile (BP 84 °C), and this small aliphatic ketone can be assumed to be rather reactive. We prepared a fresh 100-ppm standard of -thujone (Aldrich 89231; 1058112 24706082) in a 50% ethanol/water solution to quantify levels of thujone in wormwood samples. The standard was stored in several tightly sealed glass vials to be used at a later date. After four months, these standards were found to contain less than 10 ppm thujone when compared with a freshly prepared solution.
To the credit of the study, we have also found the thujone content of the wormwood samples tested to date to be very low. Following a typical recipe, the highest theoretical concentration of thujone in absinthe produced from these wormwood samples would be less than 5 ppm.