The Wormwood Society

Rapid Determination of Total Thujone in Absinthe Using 1H NMR Spectroscopy

Abstract

¹H NMR spectroscopy is utilized to quantify total thujone (sum of
𝛼
– and
𝛽
-isomers) in absinthe. For sample preparation, a simple dilution
with buffer is required. Thujone produces a distinct peak of the CH₂
group in the cyclopentanone moiety in the 2.13–2.11 ppm range. No
overlap with other typical constituents such as anethole or fenchone
occurs. The detection limit of 0.3 mg/L is adequate to control the EU
maximum limit. The relative standard deviation was 6%, and linearity was
observed from 1 to 100 mg/L. Applicability was proven by analysis of 69
authentic absinthes. The correlation between NMR and our previous
method consisting of liquid-liquid extraction followed by GC/MS was
significant (
𝑃
<
0
.
0
0
0
1
,
𝑅
=
0
.
9
3
). The simple and cheap NMR method can be used for rapid screening
of absinthes for total thujone content while chromatographic techniques
are recommended for more specific (
𝛼
– and
𝛽
-thujone isomers) analysis if required.