Determination of Essential Oils

A steam distillation is carried out with a modified distillation apparatus, as described in many pharmacopoeias (e.g. Cocking and Middleton Ph. Eur.). 

A 50-ml Erlemneyer flask is connected with a glass tube (U-shaped, 10- to 15-cm long, 5 mm in diameter). 1 g powdered drug and 10 ml water are then heated to boiling in the flask and a distillation via the U-tube is performed slowly until about 1 ml of the water-essential oil mixture has been collected in the test tube. With 1 ml pentane, the lipophilic compounds are dissolved by shaking in the upper phase the lipophilic solution is removed with a pipette and 20-100 pi is used for TLC investigation. 

Drug ConloiU of essential oil (ml/lOO g) Sample weight (B) Water (ml) Time (hr) Rate (ml/initi) 

Thcrmomicro- The use of a so-called TAS oven (Dcsaga, Germany) allows the direct application of di.slillation vegetable drug compounds that volatilize at a fairly high temperature (220°-2(i0T.) (TAS Method) without decomposition. 

A glass cartridge is filled at the tapered end with a small amount of quartz wool, followed by about 50 mg powdered drug and about 50 mg starch. The cartridge is sealed with a damp and placed in the oven block of the TAS apparatus, which is heated to about 220 C. The open end of the cartridge points directly to the TLC plate. Volatile compounds at the given temperature then distil onto the starting zone of the TI,C plate in about 1.5 min. Immediately afterwards, the plate can be placed in a solvent system sufficient for TLC separation, 

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J. A. Field, G. Nickerson, D. D. James, C. Heider, Determination of essential oils in hops by headspace SPME, J. Agric. Food Chem., 44, 1768 1772 (1996). 

Deng, C., N. Yao, A. Wang, et al. 2005. Determination of essential oil in a traditional Chinese medicine, Fructus amoni, by pressurized hot water extraction followed by liquid-liquid extraction and gas chromatography—mass spectrometry. Anal. Chim. Acta 536 237-242. 

Another important aspect to take into account for a reproducible and accurate separation and determination of essential oils is the concentration of each component. In many cases, a preconcentration of the sample, prior to any other step in the analytical process, is necessary to assure a concentration range for an accurate determination. This is the way small amounts of each constituent in plants or complex matrices, such as pharmaceuticals, can be collected and concentrated using the headspace technique (HS-GC), which involves volatilization of the terpenoids and other substances in a closely confined space, followed with analysis of constituents in the gaseous phase. This process can be carried out as an equilibrium process (static headspace) or as a continuous process (dynamic headspace). Some essential oil... 

The identification and determination of essential oils in many natural samples have improved greatly with the use of more powerful analytical techniques, such as fast extraction methods, better chromatographic detectors, and hyphenation. This improvement in analytical parameters open a great future for the development of analytical methods for essential oil determinations, even at low limits of detection. 

Sedlakova, J. Kocourkova, B. and Kuban, V. (2001). Determination of essential oils content and composition in caraway Carum carvi L.). Czech Journal of Food Sciences, 19 (1) 31-36. 

Assay In the case of herbal substances with constituents of known therapeutic activity, assays of their content are required with details of the analytical procedure. Wherever possible, a specific, stability-indicating procedure should be included to determine the content of the herbal substance. In cases where use of a nonspecific assay is justified, other supporting analytical procedures should be used to achieve overall specificity. For example, where determination of essential oils is adopted to assay the herbal substance, the combination of the assay and a suitable test for identification (e.g., fingerprint chromatography) can be used. In the case of herbal substances where the constituents responsible for the therapeutic activity are unknown, assays of marker substances or other justified determinations are required. The appropriateness of the choice of marker substance should be justified. For example, reference to the assay of a marker substance in the relevant monograph of the European Pharmacopoeia is an appropriate justification. 

Hawthorne SB, Riekkola MF, Srenius K, Holm Y, Hiltunen R, Hartonen K. Comparison of hydrodistillation and supercritical fluid extraction for the determination of essential oils in aromatic plants. J Chromatogr 1993 634 297-308. 

AI3-01601 Benzoic xid, 3,5-dinitro- 3-Carboxy-1,5-dinitrobenzene CCRIS 3129 Dinitrobenzoic acid 3,5-Dinitrobenzoic acid DNBA EINECS 202-751-1 NSC 8732. Used in chemical analysis, in identification of alcohols and chromatographic determination of essential oil constituents. Crystals mp = 205° sublimes 4m = 228 nm (e 19700, MeOH) soluble in H2O (2 g/100 ml), EtOH and glacis AcOH, less soluble in Et20, CS2, CeHe. Akzo Nobel Eka Nobel Ltd. Lancaster Synthesis Co. 

Faulharber et al (5,6) and other researchers (7-9) have described how the determination of the isotope values of constituents is of increasing importance, especially in view of the demand for authenticity control and origin determination of essential oils and foods. To determine isotope values, g chromatography-isotope ratio mass spectrometry (GC-IRMS) has been used, although not widely. The present authors (70) have studied the possibility of a more convenient and common means of analysis of isotope values, based on the isotope peak in the mass spectrum of a compound. The present study focuses on the development of a new analytical method for the differentiation of quality in commercial citrus oils of various origins. 

Jalali Heravi, M. Sereshti, H. Determination of essential oil components of Artemisia haussknechtii Boiss using simultaneous hydrodistillation-static headspace liquid phase microextraction-gas chromatography-mass spectrometry. J. Chromatogr. A, 2007,1160, 81-89. 

Improved constructions with regard to the cooling system of the aforementioned distillation apparatus have been published by Stahl (1953) and Sprecher (1963) and, in publications of Kaiser and Lang (1951) and Mechler and Kovar (1977), various apparatus used for the determination of essential oils in plant material are discussed and depicted. 

According to our recent knowledge, it is obvious that the genetic determination of essential oil compounds should be complex. Besides the direct regulation of the biosynthetic processes, other types of regulation interact with the formation of volatile compounds like intra- and intercellular transportation mechanisms, primarily metabolic processes, or regulation through transcription factors, which are still less known in terpenoid metabolism. 

Jaspersen-Schib R., Flueck H., 1962, Identi cation and purity determination of essential oils by thin layer chromatography, Congr. Sci, Farm, Conf. Commun., 21, Pisa, Italy, 1961, 608-614. 

Determination of essential oils from the leaves of two cultivars of sweet potato GC-MS HELP [25]... 

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