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

1H NMR spectroscopy is utilized to quantify total thujone (sum of - and -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 ( ). 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 ( - and -thujone isomers) analysis if required. 1. Introduction Absinthe was one of the most popular alcoholic beverages in 19th century Europe. The bitter spirit is produced using different herbs (most notably wormwood, Artemisia absinthium L.). Wormwood may contain the bicyclic monoterpene ketone thujone [1]. In recent years there is a discussion in the literature regarding the actual thujone content in alcoholic beverages and its impact on public health as it is often associated with the syndrome absinthism [2]. An overview of history, toxicity, and analytics of absinthe was recently provided by Lachenmeier et al. [1]. Historically applied methods for the thujone determination (e.g., iodometric titration [3] or use of color reagents [4]) were found to be unspecific and had inappropriate detection limits. Nowadays the most common technique for the quantification of thujone is gas chromatography (GC) combined with flame ionization detection [5, 6] or mass spectrometry (MS) [7]. Approaches for sample preparation include liquid/liquid extraction (LLE) [5, 7, 8], solid-phase extraction (SPE) [9], or headspace sampling combined with solid-phase microextraction (HS-SPME) [10, 11]. These methods are very sensitive and can provide reliable and accurate determination of both - and -thujone in bitter spirits. Nevertheless, in spite of the undoubted advantages, some difficulties exist. For instance, in some cases other compounds can coelute with thujone. Moreover, the sample preparation is often very complex and time-consuming. Therefore, from an analytical point of view, it is important to develop a fast, reliable, and accurate method for thujone determination. Another important issue is the