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.