Attenuated Total Reflectance−Fourier Transform Infrared Spectroscopy on Intact Dried Leaves of Sage (Salvia officinalis L.): Accelerated Chemotaxonomic Discrimination and Analysis of Essential Oil Composition

Sage (Salvia officinalis L.) is cultivated worldwide for its aromatic leaves, which are used as herbal spice, and for phytopharmaceutical applications. Fast analytical strategies for essential oil analysis, performed directly on plant material, would reduce the delay between sampling and analytical results. This would enhance product quality by improving technical control of cultivation. The attenuated total reflectance–Fourier transform infrared spectroscopy (ATR–FTIR) method described here provides a reliable calibration model for quantification of essential oil components [EOCs; R2 = 0.96; root-mean-square error of cross-validation (RMSECV) = 0.249 mL 100 g–1 of dry matter (DM); and range = 1.115–5.280 mL 100 g–1 of DM] and main constituents [e.g., α-thujone/β-thujone; R2 = 0.97/0.86; RMSECV = 0.0581/0.0856 mL 100 g–1 of DM; and range = 0.010–1.252/0.005–0.893 mL 100 g–1 of DM] directly on dried intact leaves of sage. Except for drying, no further sample preparation is required for ATR–FTIR, and the measurement time of less than 5 min per sample contrasts with the most common alternative of hydrodistillation followed by gas chromatography analysis, which can take several hours per sample.