Headspace Solvent Microextraction Research Articles

Gold nanorods for in-drop colorimetric determination of thiomersal after photochemical decomposition.

This work reports on the implementation of gold nanorods (AuNRs) in headspace solvent microextraction for colorimetric determination of volatile analyte derivatives in a single drop. The exposure of AuNRs to both H2Se and elemental mercury (Hg0) results in a shift of the longitudinal plasmonic band, unlike a number of volatiles. Accordingly, a method is reported for the determination of Hg0 with potential applicability to the determination of thiomersal (sodium ethylmercurithiosalicylate). It is based on the photochemical decomposition of thiomersal into Hg(II) and subsequent exposure of AuNRs-containing microdrop to in situ generated Hg0. Colorimetric analysis of the enriched drop was carried out without dilution by means of a cuvetteless microvolume UV-vis spectrometer. Under optimal conditions, the limit of detection was 0.5ngmL-1 (as Hg). The repeatability, expressed as relative standard deviation, was 8.4% (for n = 10). AuNRs exposed to increasing concentrations of the analyte were characterized by means of transmission electron microscopy and UV-vis spectrophotometry to ascertain the mechanism of detection. The method was finally applied to the determination of thiomersal in various pharmaceutical samples and showed quantitative recoveries. Graphical abstract Schematic illustration of a miniaturized colorimetric method based on the use of a microdrop of gold nanorods (AuNRs) for thiomersal determination in pharmaceuticals. It is based on the photochemical decomposition of thiomersal and subsequent Hg0 generation with in-drop amalgamation.

Deep Eutectic Solvent-Based HS-SME Coupled with GC for the Analysis of Bioactive Terpenoids in Chamaecyparis obtusa Leaves

Headspace-solvent microextraction (HS-SME) was developed as a solvent-minimized extraction technique, but few studies have examined the applications of deep eutectic solvents (DESs) to the HS-SME of bioactive compounds. In this study, HS-SME was developed for the extraction of bioactive compounds using DESs as extraction solvents. DESs, which were prepared by mixing choline chloride (ChCl) with ethylene glycol (EG) at different ratios, were applied to the extraction of three terpenoids from Chamaecyparis obtusa leaves by HS-SME. The ChCl/EG ratio in the DESs, HS-SME conditions, such as the extraction temperature and extraction time, and sample/DES ratio were optimized. All extracts were analyzed by GC. Under optimized conditions, the limits of detection were 2.006 ng mL−1 for linalool, 3.150 ng mL−1 for α-terpineol and 2.129 ng mL−1 for terpinyl acetate. The relative standard deviations were in the range of 2.1–6.8 %. The recoveries of the three terpenoids were in the range of 79.4–103 %. HS-SME is simple and rapid compared to heat reflux extraction and ultrasonic extraction. Moreover, DESs can be used in HS-SME for the extraction of a range of bioactive and volatile compounds.

Comparison of headspace solvent microextraction, hydrodistillation solvent microextraction, and solid-phase microextraction for the study of volatile components ofKelussia odoratissimaMozaff. by GC-MS

Summary Kelussia odoratissima Mozaff. is a wild and endangered endemic plant found only in limited areas of central Zagros mountains, Iran. Three microextraction methods, that is, headspace solvent microextraction (HS-SME), hydrodistillation solvent microextraction (HD-SME), and solid-phase microextraction (SPME), and a conventional hydrodistillation method were used and compared for the extraction and gas chromatography- mass spectrometric (GC-MS) analysis of volatile components of the plant. In the HS-SME and HD-SME methods, a suspended n-heptadecane microdroplet was used for the extraction from the sample headspace, while in the SPME method, a PDMS fiber was applied. The highest extraction efficiency was obtained for the SPME method, with the highest number of identified components and best precision. As a consequence, the SPME method was used for the comparison of the volatile components of seeds, leaves, and pedicles of K. odoratissima collected from three different regions. One of the major componen...

Phytotoxic Volatiles in the Roots and Shoots of Artemisia tridentata as Detected by Headspace Solid-phase Microextraction and Gas Chromatographic-mass Spectrometry Analysis

In the vicinity of big sagebrush (Artemisia tridentata), the growth of Nicotiana attenuata is negatively affected, in part due to the alleopathic effect of methyl jasmonate (MeJA) which is produced in large quantities by the aerial parts of sagebrush. Preliminary experiments suggested that growth-inhibiting substances were being emitted from the sagebrush roots. To identify the allelochemical secondary metabolites, we tested different root extracts in seedling growth bioassays with the naturally co-occurring native tobacco, Nicotiana attenuata, in a two-chamber Petri dish assay, optimized for tests of volatiles. Fractions rich in volatile compounds were particularly phytotoxic. We analyzed the volatiles emitted from the roots of intact Artemisia tridentata plants grown in soil, sand, and hydroponic cultures by using dynamic headspace extraction, headspace solvent-microextraction (HSME) and headspace solid-phase microextraction (HSPME), and GC-MS. Camphor, 1,8-cineol, nerol, and neryl isovalerate were phytotoxic and released as the major constituents. In addition to the phytotoxic monoterpenes, himachalenes, longifolene, caryophyllene, and acetylenic spiroethers, were found as characteristic components in the root's volatiles. The allelopathic potential of these root volatiles was compared with that of methyl jasmonate (MeJA), one of the most active compounds emitted from above-ground parts of the plant.

Headspace Solvent Microextraction of Volatile Components of Thymus daenensis

A headspace solvent microextraction (HSME) method for extraction of volatile components of aerial parts of Thymus daenensis subsp. daenensis plant into a microdrop is described. A comparison was made between the results obtained by HSME and a conventional hydrodistillation method. From 36 volatile components found in the hydrodistillated extract, 20 were identified and quantified in the HSME extract. The major components for both isolates were geraniol (34.9–37.2%), geranyl acetate (15.3–18.7%), geranial (9.0–11.2%), nerol (6.4–8.3%) and neral (7.1–9.3%).

Influence of the Solvent, Hydrodistillation–Headspace Solvent Microextraction and Composition of Korean Ginger

In this study, a gas chromatography–mass spectrometry method in EI mode is developed for the analysis of dried Korean ginger. Hydrodistillation–headspace solvent microextraction with polar and non-polar solvents is used. Forty-nine compounds are separated and identified. The major compounds in the rhizome identified are α-zingiberene, curcumene, camphene, β-phellandrene, (E)-citral, α-farnesene, β-bisabolene, β-sesquiphellandrene, zingerone, and [6]-gingerol.

Determination of Essential Oil Components of Star Anise (Illicium verum) Using Simultaneous Hydrodistillation–Static Headspace Liquid-Phase Microextraction–Gas Chromatography Mass Spectrometry

In this study, the hydrodistillation–headspace solvent microextraction (HD-HSME) method was used for extraction and analysis of chemical components of star anise (Illicium verum). Effective parameters for HSME, such as the nature of the extracting solvent, headspace volume, particle size of the sample, and the extraction time, were studied and optimized, and the method's performance was evaluated. The chemical compositions of the HD-HSME and HD extracts were confirmed according to their retention indexes and mass spectra (EI, 70 eV), and quantitative analysis was performed by gas chromatography (GC)–flame ionization detection (FID). Using HD-HSME followed by GC-MS, 49 compounds were separated and identified in star anise, which mainly included trans-anethole (81.4.0%), limonene (6.50%), chavicol (2.10%), and anisaldehyde (1.81%). The results of HD-HSME followed by GC-MS, in comparison with traditional the hydrodistillation method, shows that the proposed method is simple, rapid, and efficient for the determination of volatile compounds in star anise.

Headspace-solvent microextraction for identification of volatile components ofMyrtus communisL.

Summary Headspace-solvent microextraction (HS-SME) and hydrodistillation coupled with GC-MS have been used for isolation and identification of the volatile components that characterize Myrtus communis L. aroma. In the HS-SME method a suspended micro-drop of n-butanol was used as solvent. The effect of six different parameters on extraction efficiency, including sample weight, drop volume, extraction temperature, conditioning time, extraction time, and ionic strength were optimized using a simplex optimization method. The volatile components were studied both by HS-SME and an ordinary hydrodistillation method and the major components identified were 1,8-cineol, α-pinene, limonene, and linalool.

Steady-state kinetic model for headspace solvent microextraction

A general kinetic model for headspace solvent microextraction (HS-SME) is described which incorporates steady-state behavior of the concentration of the analyte in the headspace phase during the extraction process. The model is consistent with previously reported extraction rate data, and provides a fundamental framework for understanding the rate-controlling characteristics of this method. The assumptions of the model are challenged with experimental studies of HS-SME using the relatively volatile BTEX series (benzene, toluene, ethylbenzene and xylene) in which both the organic phase and headspace phase concentrations are measured directly and independently at different times during the extraction process. The experimental data provide insight into the utility and limitations of the model.

Determination of Amitraz residue by headspace Gas Chromatography in honey and Beeswax samples from Iran

Amitraz, is an acaricide used to control the infestions produced by the mite Varroa jacobsoni in the beehives. Usage of this acaricide can cause the presence of it’s residue in honey and aparian products, same as beeswax. In the last few years, Amitraz was used more frequently in Iran. With regard to increasingly public concern about health risk from pesticide residues in the diet, the analysis of amitraz residues in honey and beeswax has received special attention. Amitraz is a very labile pesticide whose degradation products contain the 2,4-dimethylaniline moiety. The method has been validated for the analysis of amitraz and DMA (one of the most abundant amitraz degradation compound) in honey is static headspace solvent microextraction Gas chromatography with Thermionic Specific Detector (GC/TSD). In this study, 70 samples honey and beeswax from different beehives (Eastern and Western Azarbayjan, Ardabil territory, Iran) , markets and store s helves of (Tehran, Iran) were collected during (2006-2007) and analysis for detection of amitraz and DMA residues. It could be concluded that according to EU standard (MRL = 200µg/kg) all the samples of honey could be declared as appropriate for human consumption.

Study of the Effects of N Fertilization and Plant Density on the Essential Oil Composition and Yield of Cuminum cyminum L. Seeds by HS–SME

Headspace-solvent microextraction (HS–SME) with sample ultrasound irradiation was successfully used for the study of the influence of nitrogen fertilization and plant density on the essential oil yield and composition of cumin (Cuminum cyminum L.) seeds. The components were collected into a single microdrop of n-heptadecane and directly injected into a GC–MS injection port for analysis. A simplex method was used for fast optimization of the extraction parameters. The experiments were executed as split-plot based on randomized complete block design. Nitrogen fertilization as the main factor (in four levels) and plant density as subsidiary factor (in three levels) were applied. It was shown that the total GC peak areas of the HS–SME extract, is proportional to the essential oil yield of the cumin seeds obtained by a hydrodistillation method. Furthermore, similar trends in the concentrations of cuminaldehyde and most other volatile components were obtained by the two methods.

Headspace solvent microextraction-gas chromatographic thermionic specific detector determination of amitraz in honey after hydrolysis to 2,4-dimethylaniline

A novel headspace solvent microextraction (HSME) method for the extraction of trace amounts of 2,4-dimethylaniline (2,4-DMA), produced after hydrolysis of amitraz, is presented. The hydrolysis reaction and HSME were carried out in a single step, and then the preconcentrated 2,4-DMA was analyzed gas chromatographically using a thermionic specific detector (TSD). Different parameters affecting the HSME procedure including the type of solvent, headspace volume, stirring rate, Na 2SO 4 content, solution and microdrop temperature, drop volume and extraction time were studied and optimized. The optimized conditions were 25 min solution equilibrium time, 10 min solvent equilibrium time, 5 mL headspace volume, 600 rpm stirring rate, 15% Na 2SO 4, solution temperature 60 °C, microdrop temperature 4 °C and microdrop volume 3 μL. The limit of detection (LOD) and limit of quantification (LOQ) of the method were 10 and 30 ng amitraz g −1 honey, respectively, and the dynamic linear range was from 0.03 to 10 μg amitraz g −1 honey. Finally, the proposed method was applied to the quantification of amitraz in spiked honey samples. Because of performing hydrolysis and extraction processes in a single step, the method provided a rapid, simple and sensitive approach to analysis of amitraz.

Rapid essential oil screening of Rosmarinus officinalis L. by hydrodistillation–headspace solvent microextraction

AbstractThe hydrodistillation–headspace solvent microextraction (HD–HSME) method was used for preconcentration and identification of the chemical composition of the essential oil of Rosmarinus officinalis L. The effect of extraction solvent, sample mass, microdrop volume and extraction time on HD–HSME efficiency were investigated and optimized. Four solvents were tested; n‐heptadecane was finally chosen as the extraction solvent and n‐hexadecane was employed as the internal standard. Two methods (hot and cold) were studied for HD–HSME and compared with hydrodistillation as the reference method. The cold method was found to be superior to the hot method. Thirty‐two compounds were identified, of which α‐pinene (48.7%), camphene (13.7%), 1,8‐cineole (13.7%), myrcene (4.5%) and camphor (2.7%) were found to be the major constituents. The results were in good correlation with those obtained by the hydrodistillation method. Copyright © 2007 John Wiley & Sons, Ltd.

Characterization and Semiquantitative Analysis of Volatile Compounds in Orange Juice by Use of Headspace-Solvent Microextraction and Gas Chromatography

By alternate use of two different extraction solvents, n-hexadecane and benzyl alcohol, a headspace-solvent microextraction (HSME)–GC–FID/MS method has been established for characterization of the volatile components of an orange juice beverage. The method avoids two disadvantages of conventional HSME—difficulty identifying components obscured by the solvent peak and inefficient extraction of some of the compounds if one solvent only is used. The optimum conditions (droplet volume, equilibration temperature and time, extraction time, and ionic strength) were determined by the factor-rotation method. The volatile components of the beverage were mainly terpenes, terpenols, fatty acids, and alcohols, for example limonene (114.71 mg L−1), phellandrene (4.50 mg L−1), terpineol (p-menth-1-en-8-ol; 3.12 mg L−1), α-pinene (0.33 mg L−1), n-hexadecanoic acid (0.28 mg L−1), and terpinol (0.13 mg L−1).

Headspace microextraction of tin into an aqueous microdrop containing pd(II) and tributyl phosphate for its determination by ETAAS

The study introduces a method for headspace solvent microextraction (HS-SME) of tin hydride into an aqueous microdrop containing Pd(II) and tributyl phosphate (TBP) as an enrichment and matrix modification method prior to ETAAS determination. The tin hydride was generated by injection of a fixed volume of sodium tetrahydroborate solution into the sample. Effects of several parameters including sample volume, amount of added NaBH4, Pd(II) and TBP concentrations in the drop, acid type and concentration in the sample, extraction time and drop volume were carefully studied. Possible interferences from a number of elements were tested and no significant interference from hydrides of other elements was observed. Salt concentrations up to 0.3 mol L-1 was tolerated by the HS-SME method while it drastically increased the background and signal absorbances in a direct injection method. The HS-SME resulted in a relatively sensitive tin determination method with a detection limit of 2.09 ng mL-1 and a precision better than 4.04% (RSD). The method was successfully applied to the determination of tin in waste water and slurry samples.

Hydrodistillation–Headspace Solvent Microextraction: An Efficient Method for Analysis of the Essential Oil from the Seeds of Foeniculum vulgare Mill.

Hydrodistillation–headspace solvent microextraction (HD–HSME) has been used for isolation and preconcentration of the essential oil from the seeds of Foeniculum vulgare Mill. The effect on extraction efficiency of different conditions, for example sample mass, extraction time, microdrop volume, and choice of solvent, was studied and all were optimized. The results were compared with those from hydrodistillation, as reference method. Fourteen compounds were identified; the main components were trans-anethole (70.4%), fenchone (9.3%), and p-allylanisole (8.8%). The results were in good agreement with those obtained by hydrodistillation.

Application of headspace solvent microextraction to the analysis of mononitrotoluenes in waste water samples

The possibility of applying headspace solvent microextraction (HSME) for determination of mononitrotoluenes (MNTs) in waste water samples is demonstrated. A drop of n-amyl alcohol containing naphthalene as an internal standard was suspended from the tip of a microsyringe needle over the headspace of stirred sample solutions for a predescribed extraction period. The drop was then injected directly into a gas chromatograph. Optimization of experimental parameters such as the nature of extracting solvent, microdrop and sample volumes, sampling temperature, stirring rate, ionic strength of the solution, pH and extraction time on HSME efficiency were investigated. Then enrichment factor, dynamic linear range (DLR), limit of detection (LOD) and precision of the method were evaluated by water samples spiked with MNTs. Finally, the method was successfully applied to the extraction and determination of the mononitrotoluenes in waste waters of both P.C.I. Company and Research Center of Azad University.

Headspace solvent microextraction-gas chromatography–mass spectrometry for the analysis of volatile compounds from Foeniculum vulgare Mill

A novel and rapid headspace solvent microextraction followed by gas chromatography–mass spectrometry (HSME-GC–MS) for the analysis of the volatile compounds of Foeniculum vulgare Mill is described. HSME parameters including extracting solvent, extraction temperature and time, headspace volume and particle size were optimized. As a result, benzyl alcohol was finally used for the extraction at 70 °C for 20 min with headspace volume of 12.1 ml and particle size of 120 mesh. Under the determined conditions, the powered samples of Foeniculum vulgare Mill were directly applied for the analysis. A comparison of HSME-GC–MS, solid phase microextraction (SPME)-GC–MS and steam distillation (SD)-GC–MS methods was made and showed that the HSME-GC–MS method was simple, inexpensive and effective and can be used for the analysis of volatile compounds in traditional Chinese medicines (TCMs).

Analysis of volatile compounds in Curcuma wenyujin Y.H. Chen et C. Ling by headspace solvent microextraction–gas chromatography–mass spectrometry

A headspace solvent microextraction–gas chromatography–mass spectrometry (HSME–GC–MS) method was described for the analysis of volatile compounds from Curcuma wenyujin Y.H. Chen et C. Ling. A comparison was made between HSME–GC–MS, solid-phase microextraction (SPME)–GC–MS and steam distillation (SD)–GC–MS methods. The number of the identified compounds was 66 for HSME–GC–MS, 71 for SPME–GC–MS and 63 for SD–GC–MS, respectively. HSME–GC–MS was found to share most of the compounds in common with the other two methods. Compared with the other two methods, HSME–GC–MS has a lower cost, more choices of extraction solvents and requires a smaller amount of sample and can directly utilizes the ground powder of traditional Chinese medicines (TCMs) for the analysis. In conclusion, HSME–GC–MS method is a simple, inexpensive and effective method for the analysis of volatile compounds in TCMs.

Analysis of n-alkanes in water samples by means of headspace solvent microextraction and gas chromatography

A simple and efficient headspace solvent microextraction (HSME) was developed for the simultaneous determination of the trace concentrations of some n-alkanes in water samples. Therefore, a microdrop of an organic solvent was extruded from the needle tip of a gas chromatographic syringe to the headspace above the surface of the solution in a sealed vial. Then the volatile organic compounds are extracted and concentrated in the microdrop. Next, the microdrop was retracted into the microsyringe and injected directly into the gas chromatograph. Experimental parameters which control the performance of HSME such as the type of microextraction solvent, organic drop and sample volume, sample stirring rate, sample solution and microsyringe needle temperatures, salt addition and exposure time profiles were investigated and optimized. Finally, the enrichment factor, dynamic linear range (DLR), limit of detection (LOD) and precision of the method were evaluated. Using optimum extraction conditions, good linearity with correlation coefficients in the range of 0.995 < r 2 < 0.999, suitable precision (%2.3 < R.S.D. < %7.2) and low detection limits (0.1–4.0 μg/l) were achieved. The HSME was performed for determination of n-alkanes in different types of natural water samples and acceptable recoveries were obtained. The results demonstrated that HSME is a rapid, accurate and effective sample preparation method and could be successfully applied for the determination of n-alkanes in water samples.