Headspace Solid-phase Microextraction Analysis Research Articles

Morphology and phytochemistry of Teucrium chamaedrys L. (Lamiaceae) cultivated at the Ghirardi Botanic Garden (Lombardy, Northern Italy)

Teucrium chamaedrys L. (Lamiaceae) cultivated at the Ghirardi Botanic Garden (Lombardy, Northern Italy) was studied through a four-level research approach: 1) micromorphological and 2) histochemical to describe the features of the glandular trichomes on the vegetative and reproductive organs and the chemical nature of their secretory products, by means of Light, Fluorescence and Scanning Electron Microscopy; 3) phytochemical, with the first characterization of the volatiles spontaneously emitted by leaves and flowers of samples of Italian origin by means of Head-Space Solid Phase Micro-Extraction (HS-SPME) coupled with Gas Chromatography–Mass Spectrometry (GC-MS); 4) ecological, through the combination of the morphological and phytochemical results with literature data concerning the ecology of the major volatile compounds.Three trichome morphotypes were observed, with a different distribution pattern on the vegetative and reproductive organs: peltates and short-stalked capitates, both ubiquitous on the whole plant, and long-stalked capitates, exclusive to the floral whorls. Both the peltates and the long-stalked capitates were recognized as the main sites of the terpene production. The HS-SPME analysis indicated that flowers displayed the most complex qualitative profile. Indeed, the vegetative and floral bouquets showed the predominance of sesquiterpene hydrocarbons and shared the main compounds, i.e., β-caryophyllene, γ-muurolene, and β-cubebene. From the literature data, a prevailing defensive action was highlighted both at the vegetative and reproductive organs level, along with the potential seductive role played by the floral bouquet.

Antinociceptive Activity of Compounds from the Aqueous Extract of Melampodium divaricatum.

A decoction prepared from the aerial parts of Melampodium divaricatum showed antinociceptive and antihyperalgesic responses when tested in the formalin model in mice. From the CH2 Cl2 fraction of the decoction, two non-previously reported secondary metabolites, 3-O-β-D-glucopyranosyl-16α-hydroxy-ent-kaurane (1) and melampodiamide (2) [(2'R*,4'Z)-2'-hydroxy-N-[(2S*,3S*,4R*)-1,3,4-trihydroxyoctadec-2-yl]tetracos-4-enamide] were separated and characterized by spectroscopic, spectrometric, and computational techniques. The flavonoids isoquercitrin and hyperoside, which possessed noted antinociceptive properties, were obtained from the active AcOEt fraction of the decoction. The chemical composition of the essential oil of the plant was also analyzed by gas chromatography-mass spectrometry. The major constituents were (E)-caryophyllene, germacrene D, β-elemene, δ-elemene, γ-patchoulene, and 7-epi-α-selinene. Headspace solid-phase microextraction analysis detected (E)-caryophyllene as the main volatile compound of the plant.

Headspace Solid-Phase Microextraction Analysis of Volatile Components in Peanut Oil.

Peanut oil is favored by consumers due to its rich nutritional value and unique flavor. This study used headspace solid-phase microextraction (HS-SPME) combined with gas chromatography (GC) and gas chromatography–mass spectrometry (GC-MS) to examine the differences in the peanut oil aroma on the basis of variety, roasting temperatures, and pressing components. The results revealed that the optimal conditions for extracting peanut oil were achieved through the use of 50/30 μm DVB/CAR/PDMS fibers at 60 °C for 50 min. The primary compounds present in peanut oil were pyrazines. When peanuts were roasted, the temperature raised from 120 °C to 140 °C and the content of aldehydes in peanut oil increased; however, the content of aldehydes in No. 9 oil at 160 °C decreased. The components of peanut shell oil varied depending on the peanut variety. The most marked difference was observed in terms of the main compound at the two roasting temperatures. This compound was a pyrazine, and the content increased with the roasting temperature in hekei oils. When the roasting temperature was lower, No. 9 oil contained more fatty acid oxidation products such as hexanal, heptanal, and nonanal. When the roasting temperature increased, No. 9 oil contained more furfural and 5-methylfurfural. Heren oil was easier to oxidize and produced nonanal that possessed a fatty aroma.

Controllable release of volatile aldehydes from polyhedral oligomeric silsesquioxane-based pro-fragrances

In the area of functional flavors and fragrances, the effective aroma and fragrance lasting are long-term challenges. To achieve this goal, an effective way is forming and cutting-off fragile covalent bonds of pro-fragrances along with controlled release of fragrances. We here report a new family of nanocarrier-based pro-fragrances, which have a high affinity to silk textiles and papers. The new pro-fragrances were prepared by using polyhedral oligomeric silsesquioxane (POSS) with perfume aldehydes, in which the formed acetal group as a linker that serves to bind the fragrance molecules allowed slow release of aldehyde molecules via hydrolysis reactions. The controllable release of volatile aldehydes was investigated in aqueous suspensions by headspace solid-phase micro-extraction analysis in combination with gas chromatography. The results show that the release of fragrances from this pro-fragrance system with headspace concentrations are 5–10 times slower than the free aldehydes.

Comparison of two commercial solid‐phase microextraction fibers for the headspace analysis of volatile compounds in different pork and beef cuts

The performance of carboxen/polydimethylsiloxane (Car/PDMS) and divinylbenzene/Car/PDMS (DVB/Car/PDMS) fibers in extracting volatile organic compounds (VOCs) from different pork and beef cuts by headspace solid-phase microextraction (HS-SPME) was compared. A principal component analysis (PCA), cluster analysis (CA), and an analysis of variance were employed subsequently to evaluate the extraction performance. DVB/Car/PDMS fibers exhibited similar VOC profiles, but were less effective than Car/PDMS fibers which showed significantly (p < 0.05) higher extraction yields of major volatile groups including acids, alcohols, aldehydes, amines, and ketones in most of the tested meat cuts. There were no significant (p > 0.05) differences in the amount of aliphatic hydrocarbon, aromatic hydrocarbon, esters, and sulfur compounds extracted by both fibers. Car/PDMS exhibited significant (p < 0.05) differences in the amount of VOCs extracted from different meat cuts, while DVB/Car/PDMS fiber did not. These findings might provide insights into HS-SPME of VOCs from different meat cuts. Practical applications The application of HS-SPME for the determination of VOCs in raw or processed meats, particularly pork and beef cuts, has been extensively studied in recent years. Among the commercial SPME fibers available, Car/PDMS and DVB/Car/PDMS fibers are the most frequently employed. However, no adequate information regarding the selection process and comparison of the fibers has been provided. The results of this study demonstrate that the profile of VOCs in different cuts of pork and beef was strongly influenced by the type of fiber used for extraction. Thus, these findings might provide new insights into the HS-SPME analysis of VOCs in different meat cuts, especially the selection of fibers for the extraction of specific VOC analytes.

Headspace Solid Phase Microextraction Analysis of Volatile Compounds of the Aerial Parts and Flowers of Plectranthus neochilus Schltr. and Salvia farinacea Benth.

The composition of the volatile compounds of the aerial parts (leaves and stems) and flowers (inflorescences) of Plectranthus neochilus Schltr. and Salvia farinacea Benth. growing in Egypt was analyzed by headspace solid phase microextraction (HS-SPME) coupled with gas chromatography/mass spectrometry (GC-MS). The analysis revealed that both the aerial parts and flowers of Plectranthus neochilus Schltr. were dominated by sesquiterpene hydrocarbons (79.9% and 63.79%), respectively. Concerning the aerial parts of Plectranthus neochilus Schltr., the major volatile components were allo-aromadendrene (19.35%) and aromadendrene (18.3%) followed by selin-3,7(11)-diene (10.2%), while γ-cadinene (18.56%) and aromadendrene (17.94%) followed by β-myrcene (10.5%) and E-β-ocimene (9.11%) were the major components in the oil of the flowers. On the other hand, the analysis revealed that 1-octen-3-ol (46.51%), 2-hexenal (18.02%), benzaldehyde (8.8%) and aromadendrene (7.24%) were the main components of the aerial parts of Salvia farinacea Benth. Ethyl benzene (24.29%) was identified as the major volatile component in the flowers followed by m-xylene (21.95%), o-xylene (7.9%), α-thujene (7.64%) and α-pinene (6.11%).

Determination of 2-Propenal Using Headspace Solid-Phase Microextraction Coupled to Gas Chromatography–Time-of-Flight Mass Spectrometry as a Marker for Authentication of Unrefined Sesame Oil

Ascertaining the authenticity of the unrefined sesame oil presents an ongoing challenge. Here, the determination of 2-propenal was performed by headspace solid-phase microextraction (HS-SPME) under mild temperature coupled to gas chromatography with time-of-flight mass spectrometry, enabling the detection of adulteration of unrefined sesame oil with refined corn or soybean oil. Employing this coupled technique, 2-propenal was detected in all tested refined corn and soybean oils but not in any of the tested unrefined sesame oil samples. Using response surface methodology, the optimum extraction temperature, equilibrium time, and extraction time for the HS-SPME analysis of 2-propenal using carboxen/polydimethylsiloxane fiber were determined to be 55°C, 15 min, and 15 min, respectively, for refined corn oil and 55°C, 25 min, and 15 min, respectively, for refined soybean oil. Under these optimized conditions, the adulteration of unrefined sesame oil with refined corn or soybean oils (1–5%) was successfully detected. The detection and quantification limits of 2-propenal were found to be in the range of 0.008–0.010 and 0.023–0.031 µg mL−1, respectively. The overall results demonstrate the potential of this novel method for the authentication of unrefined sesame oil.

Evaluation of gas freshness indicator for determination of skate (Raja kenojei) quality during storage

A gas freshness indicator consisting of the pH-sensitive dye bromothymol blue-phenol red (BTB-PR) was investigated for visible color changes of fish product quality based on the quantity of volatile amines. Chromaticity values of the gas indicator accurately tracked an increase in the ammonia content in the packaging headspace of fish products, especially skate (Raja kenojei). Gradual color changes of the gas indicator response correlated with the quality of fish including pH values during storage. Ammonia content was evaluated during the fish storage using headspace solid-phase microextraction analysis with gas chromatography-flame ionization detection. The validation results suggested that good linearity (R²=0.99) and recovery of 84.00%. The limits of detection and quantification were 8.70 and 26.30 mg/L, respectively. A pH values of skate and chromaticity of gas indicator were measured and the correlation with ammonia content was evaluated. Results of this study could prove the application of gas indicator as intelligent package for improvement of food safety.

Parameters optimization using experimental design for headspace solid phase micro-extraction analysis of short-chain chlorinated paraffins in waters under the European water framework directive

The water framework directives (WFD 2000/60/EC and 2013/39/EU) force European countries to monitor the quality of their aquatic environment. Among the priority hazardous substances targeted by the WFD, short chain chlorinated paraffins C10–C13 (SCCPs), still represent an analytical challenge, because few laboratories are nowadays able to analyze them. Moreover, an annual average quality standards as low as 0.4μgL−1 was set for SCCPs in surface water. Therefore, to test for compliance, the implementation of sensitive and reliable analysis method of SCCPs in water are required. The aim of this work was to address this issue by evaluating automated solid phase micro-extraction (SPME) combined on line with gas chromatography-electron capture negative ionization mass spectrometry (GC/ECNI–MS).Fiber polymer, extraction mode, ionic strength, extraction temperature and time were the most significant thermodynamic and kinetic parameters studied. To determine the suitable factors working ranges, the study of the extraction conditions was first carried out by using a classical one factor-at-a-time approach. Then a mixed level factorial 3×23 design was performed, in order to give rise to the most influent parameters and to estimate potential interactions effects between them. The most influent factors, i.e. extraction temperature and duration, were optimized by using a second experimental design, in order to maximize the chromatographic response.At the close of the study, a method involving headspace SPME (HS-SPME) coupled to GC/ECNI-MS is proposed. The optimum extraction conditions were sample temperature 90°C, extraction time 80min, with the PDMS 100μm fiber and desorption at 250°C during 2min. Linear response from 0.2ngmL−1 to 10ngmL−1 with r2=0.99 and limits of detection and quantification, respectively of 4pgmL−1 and 120pgmL−1 in MilliQ water, were achieved. The method proved to be applicable in different types of waters and show key advantages, such as simplicity, automation and sensitivity, required for the monitoring programs linked to the WFD.

Headspace solid-phase microextraction for wine volatile analysis

ABSTRACTThe most commonly used technique to prepare samples for the analysis of wine volatile is the headspace solid-phase microextraction (HS-SPME). This method has gained popularity in last few years, as it is a unique solventless preparation technique. In this paper, a summary of recently published studies using HS-SPME for the analysis of wine aromas, with special emphasis on the method developed, has been compiled. Several papers are discussed in detail, mainly with respect to the SPME conditions used. A brief summary of the reviews related to HS-SPME analysis is given and discussed. Several parameters affecting the HS-SPME, such as the salt concentration and the agitation conditions, are used in the same way as used in several papers. The HS-SPME extraction proved to be sufficiently sensitive to satisfy legislative requirements related to low detection and quantification limits as well as method accuracy and precision requirements. However, in order to achieve the best performance and precision, the protocol needs to be optimized for each case. The effect of different parameters must be well characterized to ensure correct extraction and desorption to ensure the transfer of extracted compounds into the analytical system. The operating parameters, such as time, temperature, and agitation, must then be kept constant for all the samples.

The use of headspace solid-phase microextraction (HS-SPME) to assess the quality and stability of fruit products: an example using red mombin pulp (Spondias purpurea L.).

The present study aimed to evaluate the volatiles profile of red mombin (Spondias purpurea) pulp and its powder produced by spray-drying (SD) as an example to show utility of headspace solid-phase microextraction (HS-SPME) in the analysis of parameters such as the quality and stability of fruit products. Volatiles profiles of the pulp were identified by gas chromatography-mass spectrometry (GC-MS), quantified by gas chromatography-flame ionization detector (GC-FID) and compared to the profile of the powder stored at 0, 60 and 120 days in plastic (PP) or laminated packages (LP). The results showed that the technique was able to identify 36 compounds in the red mombin pulp, 17 out of which have been described for the first time in this fruit, showing that red mombin fresh pulp appears to be unique in terms of volatiles composition. However, only 24 compounds were detected in the powder. This decrease is highly correlated (r2 = 0.99), at least for the majority of compounds, to the degree of volatility of compounds. Furthermore, the powder stored in PP or LP showed no statistical differences in the amounts of its components for a period of 120 days of storage. Finally, this work shows how HS-SPME analysis can be a valuable tool to assess the quality and stability of fruit products.

Comparative analysis of the aroma chemicals of Melissa officinalis using hydrodistillation and HS-SPME techniques

Headspace solid-phase micro extraction (HS-SPME) coupled with gas chromatography–mass spectrometry (GC–MS) has been used for the chemical analysis of Melissa officinalis (leaves) cultivated in Institute Germplasm. The HS-SPME analysis led to the identification of 22 components constituting 99.1% of the total volatile constituents present in the leaves whereas its hydrodistillate led to the identification of 24 volatile constituents constituting 98.1% of the volatile material. The chemical composition of the SPME and hydrodistilled extract of M. officinalis leaves comprised mainly of oxygenated monoterpenes (78.5% and 57.8% respectively) and sesquiterpene hydrocarbons (14.9% and 29.7% respectively). The major components identified in the HS-SPME extract were citronellal (31.1%), citronellol (18.3%), β-caryophyllene (12.0%), (E)-citral (11.9%), (Z)-citral (9.6%), geraniol (3.6%), (Z)-β-ocimene (3.1%) and 1-octen-3-ol (2.0%) whereas hydrodistilled essential oil was rich in (Z)-citral (19.6%), β-caryophyllene (13.2%), (E)-citral (11.2%), citronellal (10.2%), germacrene-d (8.3%), δ-3-carene (5.0%), 6-methyl-5-hepten-2-one (3.7%) and citronellyl acetate (3.7%). The comparative analysis of volatile constituents of M. officinalis leaf extract using HS-SPME and hydrodistillation techniques shows both qualitative as well as quantitative differences. The current study is the first report involving rapid analysis of volatile components of M. officinalis by HS-SPME.

Pro-oxidant/antioxidant behaviours of ascorbic acid, tocopherol, and plant extracts in n-3 highly unsaturated fatty acid rich oil-in-water emulsions

This study investigated the oxidative stability of n-3 highly unsaturated fatty acid (n-3 HUFA) rich (35% n-3 HUFA) oil-in-water emulsions (10wt% oil) with commercial antioxidants and natural plant extracts. Ascorbic acid, α-tocopherol, and the extracts of Indian gooseberry fruit (Emblica officinalis) (IGFE) and sweet basil leaves (Ocimum basilicum L.) (SBLE) were used for the study as antioxidants. The progress of oxidation in the systems was evaluated at 35°C over 120h against a control (without antioxidant) by monitoring the formation of primary (conjugated dienes) and secondary (volatile carbonyl compounds) oxidation products. Volatile carbonyl compounds were trapped as derivatives of pentafluorophenyl hydrazine and quantified by headspace solid-phase microextraction analysis. About 40 volatile carbonyls were successfully identified by this method. trans,trans-2,4-Heptadienal, trans,cis-2,4-heptadienal, 3,5-octadien-2-one, and 1-penten-3-ol were predominant. The volatile carbonyl compounds and conjugated dienes were formed at low rates in emulsion systems in which α-tocopherol and natural plant extracts had been introduced, compared to the control. Emulsion systems containing ascorbic acid showed low stability, as indicated by the oxidation products that were formed at high rates compared to the control. These results indicated that ascorbic acid activated the oxidation reactions in n-3 HUFA rich water emulsions, while natural plant extracts that were rich in polyphenols and α-tocopherol were active as antioxidants. The present study further demonstrated the applicability of the polar paradox theory in the determination of stability for n-3 HUFA rich water emulsions with commercial antioxidants and natural plant extracts.

Preparation and characterization of sodium dodecyl sulfate doped polypyrrole solid phase micro extraction fiber and its application to endocrine disruptor pesticide analysis

A robust in house solid-phase micro extraction (SPME) surface has been developed for the headspace (HS)-SPME determination of endocrine disruptor pesticides, namely, Chlorpyrifos, Penconazole, Procymidone, Bromopropylate and Lambda-Cyhalothrin in wine sample by using sodium dodecylsulfate doped polypyrrole SPME fiber. Pyrrole monomer was electrochemically polymerized on a stainless steel wire in laboratory conditions in virtue of diminishing the cost and enhancing the analyte retention on its surface to exert better selectivity and hence the developed polymerized surface could offer to analyst to exploit it as a fiber in headspace SPME analysis. The parameters, mainly, adsorption temperature and time, desorption temperature, stirring rate and salt amount were optimized to be as 70°C and 45min, 200°C, 600rpm and 10gL(-1), respectively. Limit of detection was estimated in the range of 0.073-1.659ngmL(-1) for the pesticides studied. The developed method was applied in to red wine sample with acceptable recovery values (92-107%) which were obtained for these selected pesticides.

Optimization of headspace solid-phase microextraction for analysis of β-caryophyllene in a nanoemulsion dosage form prepared with copaiba (Copaifera multijuga Hayne) oil

Recent studies have shown the anti-inflammatory activity of Copaiba oils may be addressed to the high content of β-caryophyllene, the most common sesquiterpene detected, especially in the Copaifera multijuga Hayne species. In the present study, nanoemulsions were proposed as a delivery system for copaiba oil in view to treat locally inflamed skin. This article describes the optimization and validation of a stability-indicating SPME-GC method, for β-caryophyllene analysis in the nanoemulsions produced by high pressure homogenization. SPME methods are performed with PDMS (polydimethylsiloxane) fiber (100μm). Three SPME parameters were evaluated by a three-level-three-factor Box–Behnken factorial design as potentially affecting the technique efficiency. According to the results obtained, the best conditions to extract β-caryophyllene were: (i) sampling temperature of 45°C, (ii) sampling time of 20min and (iii) no NaCl addition. Results coming from the forced degradation tests showed a reduction of β-caryophyllene peak area when both caryophyllene methanolic solution and nanoemulsions were exposed to acid hydrolysis, UV-A irradiation, oxidative (H2O2) and thermolitic (60°C) conditions. Such reduction occurred in lower extent in the nanoemulsions, suggesting a protective effect of the formulation to β-caryophyllene content. Since no degradation products were detected in the same retention time of β-caryophyllene, the specificity of the method was demonstrated. The method was linear in the range of 0.14–0.68μgmL−1 of β-caryophyllene (r2>0.999), and was also validated for precision (R.S.D.≤5.0%), accuracy (97.85–101.87%) and robustness. Finally, the method was applied to quantification of β-caryophyllene content in the developed formulations.

Comparison of Terpene Composition of Skimmia laureola Using Hydrodistillation and HS-SPME Techniques

Head space-Solid phase micro extraction (HS-SPME) technique has been used to examine terpene composition of Skimmia laureola. The chemical composition of SPME extract obtained from leaves of S. laureola was compared with composition of essential oil obtained by hydrodistillation of the same plant. Both qualitative and quantitative differences have been found in the terpene composition estimated by analyzing essential oil and HS-SPME extract of S. laureola. Gas chromatography (GC) and Gas chromatography-mass spectrometry (GC-MS) analysis of the essential oil revealed sixteen constituents, representing 99.2 % of the oil, while as HS-SPME analysis of same plant material revealed twenty six constituents, representing 98.3 % of the extract. The principal components of the essential oil were linalyl acetate (51.6 %), linalool (16.8 %), β-phellandrene (11.7 %) and α-terpineol (4.7 %), while as in the HS-SPME extract; the major constituents were linalyl acetate (49.2 %), linalool (7.5 %), α-pinene (7.3 %) and geyrene (4.9 %). The percentage yield of oil was 0.4 % ( v/w) according to their fresh weight.

Headspace Solid-phase Microextraction Analysis of the Volatile Flavour Compounds of Roasted Chickpea (Cicer arietinum L)

Headspace-solid phase microextraction coupled with gas chromatography-mass spectrometry analysis were used to provide the volatile profile of roasted chickpea as a means of unravelling and elucidating roasted chickpea as a prerequisite in developing chickpea snack item for the health and functional food sectors. The results of the HSSPME and optimization analysis using response surface methodology showed that DVB/CAR/PDMS was the most effective fibre and further results revealed the extraction temperature to be the dominant factor. A total of 61 volatile compounds were identified in the roasted chickpea. The best response within the range studied was established at 60oC extraction temperature, 30 min of equilibrium time and 15 min of extraction time. The volatile compounds identified comprised of aldehydes (25%), hydrocarbons (25%), terpenoids (20%), esters (8%), ketones (8%), alcohols (8%) and heterocyclic (8%). The results further indicated that the final model was significantly (P < 0.05) fitted for the response variable (total flavour peak area) studied with a relatively high R 2(0.9658).

Application of headspace solid-phase microextraction followed by gas chromatography–mass spectrometry to determine short-chain alkane monocarboxylic acids in aqueous samples

In this study, a procedure was developed to determine short-chain alkane monocarboxylic acids (SCMAs) in aqueous samples using headspace solid-phase microextraction (HS-SPME) followed by gas chromatography (GC) coupled with mass spectrometry (MS). A Stabilwax-DA capillary column (30 m × 0.32-mm inner diameter, 0.50-μm film thickness) was used for GC separation and a 60-μm poly(ethylene glycol) fiber was used to isolate SCMAs from water and introduce them into the gas chromatograph. Parameters of HS-SPME, analyte desorption, and GC-MS analysis were selected and an analytical procedure was proposed. Limits of quantitation were on the order of about 0.2 mg L-1. As an example of the application of the procedure, SCAMs were determined in municipal wastewater at different steps of treatment.

Characterization of volatile compounds of Daucus crinitusDesf. Headspace Solid Phase Microextraction as alternative technique to Hydrodistillation

BackgroundTraditionally, the essential oil of aromatic herbs is obtained using hydrodistillation (HD). Because the emitted volatile fraction plays a fundamental role in a plant's life, various novel techniques have been developed for its extraction from plants. Among these, headspace solid phase microextraction (HS-SPME) can be used to obtain a rapid fingerprint of a plant's headspace. Daucus crinitus Desf. is a wild plant that grows along the west coast of Algeria. Only a single study has dealt with the chemical composition of the aerial part oils of Algerian D. crinitus, in which isochavicol isobutyrate (39.0%), octyl acetate (12.3%), and β-caryophyllene (5.4%) were identified. Using GC-RI and GC-MS analysis, the essential oils and the volatiles extracted from separated organs of D. crinitus Desf. were studied using HS-SPME.ResultsGC-RI and GC-MS analysis identified 72 and 79 components in oils extracted using HD and in the volatile fractions extracted using SPME, respectively. Two types of essential oils were produced by the plant: the root oils had aliphatic compounds as the main component (87.0%-90.1%), and the aerial part oils had phenylpropanoids as the main component (43.1%-88.6%). HS-SPME analysis showed a more precise distribution of compounds in the organs studied: oxygenated aliphatic compounds were well represented in the roots (44.3%-84.0%), hydrocarbon aliphatic compounds were in the leaves and stems (22.2%-87.9%), and phenylpropanoids were in the flowers and umbels (47.9%-64.2%). Moreover, HS-SPME allowed the occurrence of isochavicol (29.6 - 34.7%) as main component in D. crinitus leaves, but it was not detected in the oils, probably because of its solubility in water.ConclusionsThis study demonstrates that HD and HS-SPME modes could be complimentary extraction techniques in order to obtain the complete characterization of plant volatiles.

Capability of headspace based sample preparation methods for the determination of methyl tert-butyl ether and benzene in reed ( phragmites australis) from constructed wetlands

In order to investigate the fate of volatile pollutants such as methyl tert-butyl ether (MTBE) and benzene during the treatment of contaminated water using constructed wetlands, appropriate analytical methods for the analysis of wetland marsh plants, in our case common reed ( Phragmites australis), are required. Different sampling procedures and different headspace (HS) based sample preparation techniques were examined to select and establish the most suited procedure for determining the target analytes in plant material. Static HS, dynamic HS and HS solid phase microextraction (SPME) in combination with GC–MS were optimized and evaluated regarding the extraction yields and their capability for quantitative analysis. Only dynamic HS analysis at 80 °C for 45 min with trapping the analytes on Tenax TA/Chromosorb-106 desorption tubes and the subsequent thermodesorption GC–MS permits the quantitative analysis of MTBE and benzene in reed in a concentration range from 4 ng up to 4 μg per sample weight (approximately 1 g). Static HS and HS SPME analyses were found to be less reliable due to the lack of suitable reference materials. Therefore, these methods do not permit the accurate quantification of pollutant content. Additionally, the HS SPME method is characterized by a restricted linear range of calibration curves. The optimized dynamic HS method was successfully applied for the quantitative analysis of MTBE and benzene within the plants. Their distribution within the plant depending on its height shows a different behavior due to differences in degradability of both substances. While a strong decrease of the concentration of benzene with increasing height of plant was found, the decrease of the concentration of MTBE was not as obvious as observed for benzene. Furthermore, the assessment of plant uptake during phytoremediation was demonstrated by analyzing complete plants for the constructed wetlands investigated.