Quantitative analysis of essential oils: a complex task

Abstract

This article provides a critical overview of current methods to quantify essential oil components. The fields of application and limits of the most popular approaches, in particular relative percentage abundance, normalized percentage abundance, concentration and true amount determination via calibration curves, are discussed in detail. A specific paragraph is dedicated to the correct use of the most widely used detectors and to analyte response factors. A set of applications for each approach is also included to illustrate the considerations.of linalool, linalyl acetate, β-pinene, sabinene, limonene and α-terpineol. 9 Figure 3 reports the enantioselective-gas chromatography-total ion mass spectrometry (ES-GC-SCAN-MS) profile of an adulterated bergamot EO together with those of linalool and linalyl acetate and α-terpineol in enantioselective-gas chromatographyselected ion monitoring mass spectrometry (ES-GC-SIM-MS) and their enantiomeric ratios.Normalized % abundance can be assumed to be a 'quantitative' comparison of GC profiles, but for some applications it is not sufficient to satisfy all quantitation Figure 3. ES-GC-TIC-MS profile of bergamot EO. (A) Peak identification: 1, α-pinene; 2, β-pinene; 3, sabinene; 4, limonene; 5, linalool; 6, linalyl acetate; 7, α-terpineol; a, (R) enantiomer; b, (S) enantiomer. ES-GC-SIM-MS profiles and enantiomeric ratios of (B) linalool and linalyl acetate (80, 93, 121 m/z) and (C) α-terpineol (59, 93, 136 m/z). Analysis conditions: column, heptakis-2,3-di-O-ethyl-6-O-t-butyldimethylsilyl-β-CD, 30% in PS086 (Megadex, Mega ® ), 25 m × 0.25 mm i.d., 0.25 μm film thickness; temperature programme, 50°C, rising at 2°C/min to 200°C, then held for 5 min; injection mode, split (ratio 1:50); injector temperature, 220°C; EI mode, 70 eV; ion source temperature, 230°C; carrier, helium; flow rate, 1.0 ml/min in constant flow mode. Full scan mode: scan range, 35-350 m/z; SIM mode: dwell time, 0.2 sFigure 4. GC profile of peppermint EO. Analysis conditions: Megawax (60 m × 0.25 mm i.d., 0.25 μm film thickness); temperature programme, 75°C for 8 min, rising at 4°C/min to 220°C, then held for 5 min; injection mode, split (ratio 1:100); injector temperature, 230°C; detector (FID) temperature, 250°C; carrier, H 2 ; flow rate, 1.5 ml/min in constant flow mode

Volatiles from leaves of field‐grown plants and shoot cultures of Gynura bicolor DC

“…Actual response factors were measured for two major compounds that were commercially available, (E)-caryophyllene and a-humulene. [22,23] GC-MS analyses were performed on an Agilent 5975 inert N mass selective detector coupled to an Agilent 6890N GC system (Palo Alto, CA, USA). Two types of fused silica capillary column with diff erent polarities were used: a DB-Wax column (60 m × 0.25 mm i.d., fi lm thickness 0.25 µm; J&W Scientifi c) and a DB-5MS column (30 m × 0.25 mm i.d., fi lm thickness 0.25 µm; J&W Scientifi c).…”

Essential oil research: past, present and future

“…Today, GC is the most commonly used method in this fi eld, advanced and highly sophisticated, with enantioselective capillary columns and coupled with mass spectroscopy (MS) or mass selective detectors (MSDs). [3] Headspace sampling and solid-phase microextraction (HS-SPME), in addition, enables the analysis of even the content of single oil glands, ducts or cavities, showing, for example, that the chemical composition diff ers between leaf insertions and leaf regions and also between the peltate and capitate oil glands of Salvia spp. [4,5] much more than in oregano [6] or peppermint.…”

“…[4,5] much more than in oregano [6] or peppermint. [7] This indicates the necessity of following the defi nition of EOs [3] and that defi ned random sampling is one of the basic preconditions to obtain comparable and reproducible analytical results. …”

Development of techniques for capillary chromatography of terpene hydrocarbons and oxygenated components of essential oils

“…Публикации по теории газохроматографического анализа природных летучих фракций в большей мере сосредоточены в химических, медицинских журна-лах [9,10]. В меньшей мере изучение носителей аро-мата, особенно природного происхождения представ-лено в журналах пищевой науки.…”