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

H-1 NMR spectroscopy is utilized to quantify total thujone (sum of alpha-and beta-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 0.3mg/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 < 0.0001, R = 0.93). 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 (alpha-and beta-thujone isomers) analysis if required.