Analytical Chemistry Insights

A methodology that utilizes 1H-NMR spectroscopy has been developed to simultaneously analyze toxic terpenes (thujone and camphor), major polyphenolic compounds, the total antioxidant capacity (ORAC) and the Folin-Ciocalteu (FC) index in foods and medicines containing sage. The quantitative determination of rosmarinic acid (limit of detection (LOD) = 10 mg/L) and total thujone (LOD = 0.35 mg/L) was possible using direct integration of the signals. For other parameters (derivatives of rosmarinic acid, carnosol and flavone glycosides, ORAC and FC index), chemometric regression models obtained separately for alcohol-based tinctures (R2 = 0.94–0.98) and aqueous tea infusions (R2 = 0.79–0.99) were suitable for screening analysis. The relative standard deviations for authentic samples were below 10%. The developed methodology was applied for the analysis of a wide variety of sage products (n = 108). The total thujone content in aqueous tea infusions was found to be in the range of not detectable (nd) to 37.5 mg/L (average 9.2 mg/L), while tinctures contained higher levels (range nd—409 mg/L, average 107 mg/L). The camphor content varied from 2.1 to 43.7 mg/L in aqueous infusions and from not detectable to 748 mg/L in tinctures (averages were 14.1 and 206 mg/L, respectively). Phenolic compounds were also detected in the majority of the investigated products. 1H-NMR spectroscopy was proven to have the ability to holistically control all important adverse and beneficial compounds in sage products in a single experiment, considerably saving time, resources and costs as NMR replaces four separate methodologies that were previously needed to analyze the same parameters.