Rapid Analysis of the Essential Oil of Acorus tatarinowii Schott by Microwave Distillation, SPME, and GC-MS

The dry rhizome of Acorus tatarinowii Schott is a traditional Chinese medicine (TCM) which has been used to treat many diseases, for example epilepsy, for thousands of years. In this work, microwave distillation and simultaneous solid-phase microextraction (MD-SPME) were used for analysis of the essential oil in the fresh leaves of Acorus tatarinowii. Isolation, extraction, and concentration of the volatile constituents of the leaves can be completed rapidly, in a single step, by use of MD-SPME; the compounds can then be analyzed by gas chromatography-mass spectrometry (GC-MS). MD-SPME conditions, including microwave power, irradiation time, and SPME fiber coating, were studied. By use of MD-SPME-GC-MS twenty-nine compounds were identified, for the first time, in the essential oil of the plant leaves; the compounds were the same as those in the rhizomes. This suggests the leaves of the plant might be used as a TCM. To demonstrate the feasibility of the method, conventional steam distillation (SD) was also used for extraction of the essential oil from the leaves. The same compounds, in similar amounts, were identified by both methods, confirming the MD-SPME method is highly reliable. Compared with SD, MD-SPME required less time (only 2 min), less sample (1.0 g), and no organic solvent. These results are indicative of the suitability of MD-SPME-GC-MS for simple, rapid, and solvent-free analysis of plant essential oils.     

Ultrasound-Microwave Hybrid-Assisted Extraction Coupled to Headspace Solid-Phase Microextraction for Fast Analysis of Essential Oil in Dry Traditional Chinese Medicine by GC–MS

A novel one-step sample preparation technique termed ultrasound-microwave hybrid-assisted extraction coupled to headspace solid-phase microextraction (UMHE-HS-SPME) was developed in this study, which was used for the determination of essential oils in dry traditional Chinese medicine (TCM) based on gas chromatography–mass spectrometry. The dry roots of Angelica dahurica were used as the model TCM. In this work, ultrasound-assisted extraction was first combined with microwave-assisted extraction coupled to headspace solid-phase microextraction and applied to the rapid determination of A. dahurica. Sample preparations including isolation, extraction, and concentration of essential oils were performed in a single step. The effects of various parameters including fiber coating, ultrasound power, and irradiation time were investigated thoroughly and optimized. To further demonstrate the method’s feasibility, the conventional steam distillation (SD) method was used for the analysis of essential oils in the TCM to compare with the proposed method. The results show that more essential oil compounds were isolated and identified by UMHE-HS-SPME than by SD. Moreover, compounds with higher boiling point and many more oxygenated compounds were extracted from A. dahurica by the proposed method. In addition, the SD method required a long time (6 h) to isolate the essential oils, and large amounts of organic solvent for further extraction, while UMHE-HS-SPME needed only 10 min to prepare the samples, and no organic solvent. Relative standard deviation values less than 10 % show that the present method has good precision. According to the experimental results, the advantages of the proposed method are: short extraction time, high extraction efficiency, and solvent-free extraction. Thus, UMHE-HS-SPME is an alternative tool for fast analysis of essential oils in dry TCMs and can be potentially extended to other target analytes in dry matrix.     

Rapid determination of volatile constituents in safflower by microwave distillation and simultaneous solid-phase microextraction coupled with gas chromatography-mass spectrometry

In this paper, microwave distillation and solid-phase microextraction coupled with gas chromatography-mass spectrometry (MD-SPME/GC-MS) was developed for the analysis of essential components in safflower. Using the MD-SPME technique, the isolation, extraction and concentration of volatile compounds in safflower were carried out in only one step. Some parameters affecting the extraction efficiency such as SPME fiber coating, microwave power, irradiation time and the volume of water added were optimized. The optimal experiment parameters obtained were: 65 microm CW/DVB SPME fiber, a microwave power of 400 W, an irradiation time of 3 min and water volume of 1 mL. The proposed method has been compared with conventional steam distillation (SD) for extraction of essential oil compounds in safflower. Using MD-SPME followed by GC-MS, 32 compounds in safflower were separated and identified, which mainly included paeonol, alpha-asarone, beta-asarone, 1-methyl-4-(2-propenyl)-benzene and diethenyl-benzene, whereas only 18 compounds were separated and identified by conventional SD followed by GC-MS. The relative standard deviation (R.S.D.) values of less than 10% show that the proposed method has good reproducibility. The results show that MD-SPME/GC-MS is a simple, rapid, effective method for the analysis of volatile oil components in safflower.     

Rapid analysis of the essential oil components of dried Zanthoxylum bungeanum Maxim by Fe2O3‐magnetic‐microsphere‐assisted microwave distillation and simultaneous headspace single‐drop microextraction followed by GC–MS

In this work, microwave distillation assisted by Fe₂O₃ magnetic microspheres (FMMS) and headspace single‐drop microextraction were combined, and developed for determination of essential oil compounds in dried Zanthoxylum bungeanum Maxim (ZBM). The FMMS were used as microwave absorption solid medium for dry distillation of dried ZBM. Using the proposed method, isolation, extraction, and concentration of essential oil compounds can be carried out in a single step. The experimental parameters including extraction solvent, solvent volume, microwave power, irradiation time, and the amount of added FMMS, were studied. The optimal analytical conditions were: 2.0 μL decane as the extraction solvent, microwave power of 300 W, irradiation time of 2 min, and the addition of 0.1 g FMMS to ZBM. The method precision was from 4 to 10%. A total of 52 compounds were identified by the proposed method. The conventional steam distillation method was also used for the analysis of essential oil in dried ZBM and only 31 compounds were identified by steam distillation method. It was found that the proposed method is a simple, rapid, reliable, and solvent‐free technique for the determination of volatile compounds in Chinese herbs.     

Development of gas chromatography-mass spectrometry following microwave distillation and simultaneous headspace single-drop microextraction for fast determination of volatile fraction in Chinese herb

In this work, for the first time, microwave distillation (MD) coupled with simultaneous headspace single-drop microextraction (HS-SDME) was developed for the determination of the volatile components in the Chinese herb, Artemisia capillaris Thunb. The volatile components were rapidly isolated by MD, and simultaneously extracted and concentrated by using a dodecane microdrop. The volatile oil extracted in the microdrop solvent was analyzed by gas chromatography-mass spectrometry (GC-MS). The experimental parameters of solvent selection, microdrop volume, microwave power, irradiation time and sample amount were investigated, and the method precision was also studied. The optimal parameters were extraction solvent of dodecane, solvent volume of 2.0 microL, microwave power of 400 W, irradiation time of 4 min, and sample amount of 2.0 g. Thirty-five volatile compounds present in Artemisia capillaris Thunb. were identified by using the proposed method, which were identical with those obtained by the conventional steam distillation method. The experimental results showed that MD-HS-SDME is a simple, rapid, reliable, and solvent-free technique for the determination of volatile compounds in Chinese herbs.     

Water as a green solvent combined with different techniques for extraction of essential oil from lavender flowers

Using water as a green solvent with a variable geometry makes use of physical and chemical phenomena that are fundamentally different from those applied in conventional extraction techniques such as hydro-distillation, steam distillation or solvent extraction. Advantages and drawbacks of using water as a solvent with different physical and chemical states have been compared. A total of ten extraction techniques: hydro-distillation (HD), steam distillation (SD), turbo-hydro-distillation (THD), salt-hydro-distillation (NaCL-HD), enzyme-hydro-distillation (Enzyme-HD), micelle-hydro-distillation (Micelle-HD), ultrasound-hydro-distillation (US-HD) or subcritical water-hydro-distillation (SW-HD), solvent-free microwave extraction (SFME) and microwave steam distillation (MSD) were used to extract the essential oil from lavender (Lavandula L.) and their results were compared. The quantity was measured by the yield of essential oil and the quality was evaluated using the oil composition especially the content of linalyl acetate, linalool and terpin-4-ol compared with the corresponding control sample: Hydro-distillation. For environmentally friendly of the process: extraction time, total energy consumption and CO₂ emission were considered and compared with conventional hydro-distillation. The mechanism explaining the linalyl acetate degradation has been resolved by using COSMO-RS software. Based on the present experimental conditions, it is recommended that lavender oil may be produced preferably by steam distillation assisted by microwave extraction to reduce the by-product formation by various chemical reactions and to get better oil recoveries.     

An integrated simultaneous distillation–extraction apparatus for the extraction of essential oils from herb materials and its application in Flos Magnoliae

A large number of herb materials contain essential oils with extensive bioactivities. In this work, an integrated simultaneous distillation–extraction (ISDE) apparatus was developed. To demonstrate its feasibility, the performance of ISDE was evaluated for the extraction of essential oil from Flos Magnoliae and compared with conventional techniques including steam distillation (SD) and simultaneous distillation–extraction (SDE). According to the product yield, the time consumed and the composition of oil, the essential oils isolated by ISDE were better than that obtained by SD and similar to those obtained by SDE. ISDE was also better than SDE due to its simple operation and lower consumption of energy and organic solvent. Copyright © 2009 John Wiley & Sons, Ltd.     

Microwave-assisted steam distillation for the determination of organochlorine pesticides and pyrethroids in Chinese teas

In this work, microwave-assisted steam distillation (MASD) extraction method followed by gas chromatography/electron capture detection (GC/ECD) was developed for the determination of organochlorine pesticides (OCPs) and pyrethroids in the Chinese teas. MASD is a combination of microwave-assisted extraction (MAE) and steam distillation techniques. Water vapor generated by microwave irradiation is used to accelerate desorption of the analytes from the sample, and the nonpolar organic solvent used for trapping the analytes is kept from direct contact with the sample by the water. Therefore, relatively clean extracts were obtained compared to the method directly using organic solvent as extraction solvent, such as ultrasonic extraction (USE). Microwave power of 200 W and irradiation time of 2 min was found to be the optimum conditions for the MASD process, and n-heptane was chosen as the analyte-trapping solvent in the study. Five OCPs (α-HCH, γ-HCH, dicofol, p,p′-DDE, p,p′-DDT) and two pyrethroids (bifenthrin, fenvalate) were determined using this extraction method in the tea samples. The relative standard deviation (R.S.D.) of the analytes varied from 2.2 to 8.4%, and the method detection limits (MDLs) found were lower than 0.23 μg/kg. The recoveries of the seven compounds in the Jasmine tea sample were between 84.04 and 110.1%. Comparative results obtained by MASD and USE were also discussed in the study.     

Comparison of different extraction methods for the determination of essential oils and related compounds from aromatic plants and optimization of solid-phase microextraction/gas chromatography

Different extraction methods for the subsequent gas chromatographic determination of the composition of essential oils and related compounds from marjoram (Origanum majorana L.), caraway (Carum carvi L.), sage (Salvia officinalis L.), and thyme (Thymus vulgaris L.) have been compared. The comparison was also discussed with regard to transformation processes of genuine compounds, particularly in terms of expenditure of time. Hydrodistillation is the method of choice for the determination of the essential oil content of plants. For investigating the composition of genuine essential oils and related, aroma-active compounds, hydrodistillation is not very useful, because of discrimination and transformation processes due to high temperatures and acidic conditions. With cold solvent extraction, accelerated solvent extraction, and supercritical fluid extraction, discrimination of high and non-volatile aroma-active components as well as transformation processes can be diminished, but non-aroma-active fats, waxes, or pigments are often extracted, too. As solid-phase microextraction is a solvent-free fully automizable sample preparation technique, this was the most sparing to sensitive components and the most time-saving method for the rapid determination of the aroma compounds composition in marjoram, caraway, sage, and thyme. Finally, solid-phase microextraction could be successfully optimized for the extraction of the aroma components from the plants for their subsequent gas chromatographic determination.     

Microwave-Assisted Extraction/Dispersive Liquid–Liquid Microextraction Coupled with DSI-GC-IT/MS for Analysis of Essential Oil from Three Species of Cardamom

A novel method of microwave-assisted extraction coupled with polyethylene Pasteur-pipette-based dispersive liquid–liquid microextraction applying low-density organic solvent (MAE-LDS-DLLME) was successfully developed for extraction and preconcentration of essential oil from three species of cardamom (Semen Alpiniae Katsumadai, Fructus Amomi Rotundus, and Semen Myristicae). The essential oil was analyzed by gas chromatography-ion trap/mass spectrometry (GC-IT/MS) using a ChromatoProbe direct sample introduction (DSI) device. The effects of various parameters affecting the extraction process, such as the type of extraction solvent and dispersive solvent, ionic strength, microwave power, and irradiation time, were investigated thoroughly and optimized. The optimal conditions were extraction solvent of toluene, dispersive solvent of methanol, microwave power of 80 W, irradiation time of 4.0 min, plant material amount of 0.1 g, and no addition of salt. Compared with hydrodistillation, MAE-DLLME-DSI-GC–MS is a simple, rapid, low-cost, efficient, and environmentally friendly method, and the essential oil contains higher amounts of oxygenated compounds, which play an important and valuable role in terms of their contribution to the fragrance of the essential oil. In this work, we also studied the main components of the three varieties of cardamom. Qualitative and quantitative differences in the components of the three essential oils were found to be present. Based on comparison of the main bioactive compounds of essential oil, a significant difference was found between Semen Alpiniae Katsumadai or Fructus Amomi Rotundus and Semen Myristicae. This study also provides a new approach for quality assessment of traditional Chinese medicines.     

Fast determination of Z-ligustilide in plasma by gas chromatography/mass spectrometry following headspace single-drop microextraction

Angelica sinensis (danggui in Chinese) is a common traditional Chinese medicine (TCM), and its essential oil has been used for the treatment of many diseases such as hepatic fibrosis. Z-Ligustilide has been found to be an important active component in the TCM essential oil. In this work, for the first time, headspace single-drop microextraction (HS-SDME) followed by gas chromatography-mass spectrometry (GC-MS) was developed for the determination of Z-ligustilide in rabbit plasma after oral administration of essential oil of danggui. The extraction parameters of solvent selection, solvent volume, sample temperature, extraction time, stirring rate, and ion strength were systemically optimized. Furthermore, the method linearity, detection limit, and precision were also investigated. It was shown that the proposed method provided good linearity (0.02-20 microg/mL, R2 = 0.997), low detection limit (10 ng/mL), and good precision (RSD value less than 9%). Finally, HS-SDME followed by GC/MS was used for fast determination of Z-ligustilide in rabbit plasma at different time intervals after oral administration of danggui essential oil. The experimental results suggest that HS-SDME followed by GC/MS is a simple, sensitive, and low-cost method for the determination of Z-ligustilide in plasma, and a low-cost approach to pharmacokinetics studies of active components in TCMs.     

Determination of Camphor and Borneol in Traditional Chinese Medicines by Microwave-assisted Extraction and Gas Chromatography with Flame Ionization Detector

Abstract

In this work, microwave-assisted extraction (MAE) followed by gas chromatography with flame ionization detector (GC–FID) was developed for the rapid determination of camphor and borneol in three traditional Chinese medicines (TCM): Chrysanthemi indici, Flos Chrysanthemi indici and Amomum villosum lour. The optimal MAE conditions obtained were: acetone for solvent, with solvent having sample ratio of 12:1 (v/w); microwave power of 380 W, and an irradiation time of 4 min. Method validations were also studied. To demonstrate the proposed method, ultrasonic-assisted extraction (UAE) and steam distillation (SD), followed by GC-FID, were used to analyze camphor and borneol in thethree TCMs. The close results were obtained by the three methods. The results showed that the proposed MAE–GC–FID is a simple, rapid, and reliable method for quantitative analysis of camphor and borneol in TCM, and is also a potential tool for TCM quality assessment.     

Development of microwave-assisted extraction followed by headspace solid-phase microextraction and gas chromatography-mass spectrometry for quantification of camphor and borneol in Flos Chrysanthemi Indici

In the work, microwave-assisted extraction (MAE) followed by headspace solid-phase microextraction (HS-SPME) and gas chromatography-mass spectrometry (GC-MS) was developed for quantitative analysis of the bioactive components of camphor and borneol in a traditional Chinese medicines (TCM) of Flos Chrysanthemi Indici. After systematical investigation, the optimal experimental parameters microwave power (400 W), irradiation time (4 min), fiber coating (PDMS/DVB fiber), extraction temperature (40 °C), extraction time (20 min), stirring rate (1100 rpm), and salt effect (no salt added) were investigated. The optimized method provided satisfactory precision (RSD values less than 12%), good recovery (from 86% to 94%), and good linearity (R² > 0.999). The proposed method was applied to quantitative analysis of camphor and borneol in Flos Chrysanthemi Indici samples from 11 different growing areas. To demonstrate the method feasibility, steam distillation was also used to analyze camphor and borneol in Flos Chrysanthemi Indici samples from these different growing areas. The very close results were obtained by the two methods. It has been shown that the proposed ME-HS-SPME-GC-MS is a simple, rapid, solvent-free and reliable method for quantitative analysis of camphor and borneol in TCM, and a potential tool for quality assessment of Flos Chrysanthemi Indici.     

Application of PLE for the determination of essential oil components from Thymus vulgaris L

Essential plants, due to their long presence in human history, their status in culinary arts, their use in medicine and perfume manufacture, belong to frequently examined stock materials in scientific and industrial laboratories. Because of a large number of freshly cut, dried or frozen plant samples requiring the determination of essential oil amount and composition, a fast, safe, simple, efficient and highly automatic sample preparation method is needed.Five sample preparation methods (steam distillation, extraction in the Soxhlet apparatus, supercritical fluid extraction, solid phase microextraction and pressurized liquid extraction) used for the isolation of aroma-active components from Thymus vulgaris L. are compared in the paper. The methods are mainly discussed with regard to the recovery of components which typically exist in essential oil isolated by steam distillation.According to the obtained data, PLE is the most efficient sample preparation method in determining the essential oil from the thyme herb. Although co-extraction of non-volatile ingredients is the main drawback of this method, it is characterized by the highest yield of essential oil components and the shortest extraction time required. Moreover, the relative peak amounts of essential components revealed by PLE are comparable with those obtained by steam distillation, which is recognized as standard sample preparation method for the analysis of essential oils in aromatic plants.     

Comparison of solid-phase microextraction, supercritical fluid extraction, steam distillation, and solvent extraction techniques for analysis of volatile consituents in Fructus Amomi

Four sampling techniques, solid-phase microextraction (SPME), supercritical fluid extraction (SFE), steam distillation (SD), and solvent extraction (SE), were compared for the analysis of volatile constituents from a traditional Chinese medicine (TCM) of the dried ripe fruit of Fructus Amomi (Sha Ren). A total of 38 compounds were identified by gas chromatography/mass spectrometry. Different SFE and SPME parameters (modifier content, extraction pressure, and temperature for SFE and fibers, extraction temperature, and time for SPME) were studied. The results by SFE and SPME were compared with those obtained by conventional SD and SE methods. The results showed that SFE and SPME are better sample preparation techniques than SD and SE. Due to SFE's requirement for expensive specialized instrumentation, the simplicity, low cost, and speed of SPME make it a more appropriate technique for extraction of volatile constituents in TCMs.     

Determination of volatile compounds in Magnolia bark by microwave-assisted extraction coupled to headspace solid-phase microextraction and gas chromatography-mass spectrometry.

A method is described for the determination of volatile compounds in Magnolia bark using microwave-assisted extraction coupled to headspace solid-phase microextraction (MAE-HS-SPME), followed by gas chromatography with mass spectrometry (GC-MS). Parameters affecting the extraction efficiency, such as sampling time and temperature, microwave irradiation power and desorption time, were investigated to achieve the optimal conditions. The result obtained was compared with that of steam distillation; only small differences existed between these two methods. Therefore, the proposed method seems to be a feasible and relatively simple, fast and solvent-free procedure for identification of essential oils in Magnolia bark.     

Solid-phase microextraction of hop volatiles. Potential use for determination and verification of hop varieties

The composition of hop essential oil is an important tool for evaluation of hop quality. As each hop variety has a typical essential oil pattern (fingerprint), hop oil analyses can be used to distinguish between hop varieties. The headspace solid-phase microextraction (SPME) method as described in this contribution is a simple sample preparation technique and represents an alternative procedure for essential oil fingerprint determination. Different SPME parameters (extraction temperature, extraction time and sample mass) were studied and the results were compared with those obtained by the routine distillation method. It is shown that SPME results can be used for determination and verification of varieties grown in Slovenia by means of principal components analysis.     

Subcritical water extraction of organic matter from sedimentary rocks

Subcritical water extraction of organic matter containing sedimentary rocks at 300 °C and 1500 psi produces extracts comparable to conventional solvent extraction. Subcritical water extraction of previously solvent extracted samples confirms that high molecular weight organic matter (kerogen) degradation is not occurring and that only low molecular weight organic matter (free compounds) are being accessed in analogy to solvent extraction procedures. The sedimentary rocks chosen for extraction span the classic geochemical organic matter types. A type I organic matter-containing sedimentary rock produces n-alkanes and isoprenoidal hydrocarbons at 300 °C and 1500 psi that indicate an algal source for the organic matter. Extraction of a rock containing type II organic matter at the same temperature and pressure produces aliphatic hydrocarbons but also aromatic compounds reflecting the increased contributions from terrestrial organic matter in this sample. A type III organic matter-containing sample produces a range of non-polar and polar compounds including polycyclic aromatic hydrocarbons and oxygenated aromatic compounds at 300 °C and 1500 psi reflecting a dominantly terrestrial origin for the organic materials. Although extraction at 300 °C and 1500 psi produces extracts that are comparable to solvent extraction, lower temperature steps display differences related to organic solubility. The type I organic matter produces no products below 300 °C and 1500 psi, reflecting its dominantly aliphatic character, while type II and type III organic matter contribute some polar components to the lower temperature steps, reflecting the chemical heterogeneity of their organic inventory. The separation of polar and non-polar organic compounds by using different temperatures provides the potential for selective extraction that may obviate the need for subsequent preparative chromatography steps. Our results indicate that subcritical water extraction can act as a suitable replacement for conventional solvent extraction of sedimentary rocks, but can also be used for any organic matter containing mineral matrix, including soils and recent sediments, and has the added benefit of tailored extraction for analytes of specific polarities.     

Comparative study of extraction techniques for determination of garlic flavor components by gas chromatography–mass spectrometry

Several sampling techniques based on steam distillation (SD), simultaneous distillation and solvent extraction (SDE), solid-phase trapping solvent extraction (SPTE), and headspace solid-phase microextraction (HS-SPME) have been compared for the determination of Korean garlic flavor components by gas chromatography–mass spectrometry (GC–MS). Diallyl disulfide (57.88%), allyl sulfide (23.59%), and diallyl trisulfide (11.40%) were found to be the predominant flavor components of garlic samples extracted by SDE whereas these components were at levels of 89.77%, 2.43%, and 3.89% when the same sample was extracted by SD, 97.77%, 0.17%, and 0.10% by SPTE, and 97.85%, 0.01%, and 0.01% by HS-SPME using the 50/30-m divinyl benzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS) fiber. Thermal degradation of components such as allyl methyl sulfide, dimethyl disulfide, and thiirane were observed for SDE and SD but not for SPTE or HS-SPME. HS-SPME had several advantages compared with SD, SDE, and SPTE—rapid solvent-free extraction, no apparent thermal degradation, less laborious manipulation, and less sample requirement. Five different fiber coatings were evaluated to select a suitable fiber for HS-SPME of garlic flavor components. DVB/CAR/PDMS was most efficient among the five types of fiber investigated.     

Development of gas chromatography/mass spectrometry following headspace solid-phase microextraction for fast determination of asarones in plasma

Asarones (alpha-asarone and beta-asarone) are the active components in the traditional Chinese medicine (TCM) of Acorus tatarinowii Schott, which has been used to treat epilepsy for several thousand years. To perform the pharmacokinetics (PK) study of alpha- and beta-asarone from the TCM essential oil, a simple, rapid and sensitive method was developed for the determination of asarones from the TCM in rabbit plasma, based on headspace solid-phase microextraction (HS-SPME) followed by gas chromatography/mass spectrometry (GC/MS) with electron ionization (EI). The extraction parameters of headspace volume, fiber coating, sample temperature, extraction time, stirring rate and ion strength were systemically optimized. Furthermore, the method linearity, detection limit and precision were also investigated. It was shown that the proposed method provided a good linearity (0.02-20 microg/mL, R(2) > 0.99), low detection limit (<2.0 ng/mL) and good precision (RSD < 7.0%). Finally, HS-SPME followed by GC/MS was applied to fast determination of alpha- and beta-asarone in rabbit plasma at different time points after oral adminstration of the essential oil from A. tatarinowii. The experimental results suggest that the proposed method provides an alternative approach to the PK studies of volatile compounds in TCMs.