Headspace Solid Phase Microextraction Coupled to GC/MS for the Analysis of Volatiles of Honeys from Arid and Mediterranean Areas of Algeria

The volatile composition of seven honey samples collected from various regions of Algeria and feeding on different plants have been determined. The Headspace Solid‐Phase MicroExtraction (HS‐SPME) coupled with Gas Chromatography‐Mass Spectrometry (GC/MS) was used to achieve the purpose. In this work, different parameters of the HS‐SPME analytical method were investigated in order to reach maximal sensitivity, and thus to obtain maximum information about the volatile profile of Algerian honey. These parameters include saline medium, HS extraction temperature, and the nature of the fiber used. The results showed a great diversity in the chemical composition, in total 124 compounds from different chemical classes were identified, including compounds found for the first time in honey. The Ascending Hierarchical Classification (AHC) demonstrated the importance of choosing SPME extraction conditions to find volatile compounds, which could be as specific markers of the floral or geographical origin of honey, the latter was optimized in the parameter PDMS‐55 °C.     

Solid-phase microextraction and the human fecal VOC metabolome

The diagnostic potential and health implications of volatile organic compounds (VOCs) present in human feces has begun to receive considerable attention. Headspace solid-phase microextraction (SPME) has greatly facilitated the isolation and analysis of VOCs from human feces. Pioneering human fecal VOC metabolomic investigations have utilized a single SPME fiber type for analyte extraction and analysis. However, we hypothesized that the multifarious nature of metabolites present in human feces dictates the use of several diverse SPME fiber coatings for more comprehensive metabolomic coverage. We report here an evaluation of eight different commercially available SPME fibers, in combination with both GC-MS and GC-FID, and identify the 50/30 μm CAR-DVB-PDMS, 85 μm CAR-PDMS, 65 μm DVB-PDMS, 7 μm PDMS, and 60 μm PEG SPME fibers as a minimal set of fibers appropriate for human fecal VOC metabolomics, collectively isolating approximately 90% of the total metabolites obtained when using all eight fibers. We also evaluate the effect of extraction duration on metabolite isolation and illustrate that ex vivo enteric microbial fermentation has no effect on metabolite composition during prolonged extractions if the SPME is performed as described herein.     

Solid-phase microextraction for determining twelve orange flavour compounds in a model beverage emulsion

Solid-phase microextraction (SPME) coupled to gas chromatography has been applied for the headspace analysis (HS) of 12 target flavour compounds in a model orange beverage emulsion. The main volatile flavour compounds studied were: acetaldehyde, ethyl acetate, alpha-pinene, ethyl butyrate, beta-pinene, myrcene, limonene, gamma-terpinene, octanal, decanal, linalool and citral (neral plus geranial). After screening the fibre type, the effect of other HS-SPME variables such as adsorption temperature (25-55 degrees C), extraction time (10-40 min), sample concentration (1-100% w/w), sample amount (5-10 g) and salt amount (0-30% w/w) were determined using a two-level fractional factorial design (2(5-2)) that was expanded further to a central composite design. It was found that an extraction process using a carboxen-polydimethylsiloxane fibre coating at 15 masculineC for 50 min with 5 g of diluted emulsion 1% (w/w) and 30% (w/w) of sodium chloride under stirring mode resulted in the highest HS extraction efficiency. For all volatile flavour compounds, the linearity values were accurate in the concentration ranges studied (r(2) > 0.97). Average recoveries that ranged from 90.3 to 124.8% showed a good accuracy for the optimised method. The relative standard deviation for six replicates of all volatile flavour compounds was found to be less than 15%. For all volatile flavour compounds, the limit of detection ranged from 0.20 to 1.69 mg/L.     

糖蜜草挥发性成分HS-SPME-GC-MS分析

本文首次采用顶空固相微萃取技术(HS-SPME)提取该植物挥发性成分,然后通过气质联用技术(GC-MS)结合保留指数以及标样对照对化学成分进行了定性,并通过峰面积归一化法计算出各组分的相对百分含量。试验确定了PDMS/DVB固相微萃取对糖蜜草挥发物的萃取效果最好,并从中鉴定出33种化合物占总挥发性成分的90.94%,主要为烷烃和萜烯类化合物。该研究为开发糖蜜草作为水稻螟虫的驱避植物进行害虫安全有效防治提供理论依据,并为驱避性挥发物的田间应用奠定基础。     

Solid-phase microextraction gas chromatographic–mass spectrometric method for the determination of inhalation anesthetics in urine

Solid-phase microextraction (SPME) has been applied to the headspace sampling of inhalation anesthetics (i.e. nitrous oxide, isoflurane and halothane) in human urine. Analysis was carried out by gas chromatography–mass spectrometry using a capillary column with a divinylbenzene porous polymeric stationary phase. A SPME divinylbenzene–Carboxen–polydimethylsiloxane coated fiber, 2 cm long, was used, and its performances were compared with those of a Carboxen–PDMS in terms of sensitivity, extraction efficiency, extraction time, fiber coating–urine distribution coefficient. For both fibers, linearity was established over four orders of magnitude, limits of detection were below 100 ng/l for nitrous oxide and below 30 ng/l for halogenated. Precision calculated as %RSD was within 3–13% for all intra- and inter-day determinations. The method was applied to the quantitative analysis of anesthetics in the urine of occupationally exposed people (operating room personnel).     

GC-MS SPME profiling of rhizobacterial volatiles reveals prospective inducers of growth promotion and induced systemic resistance in plants

Chemical and plant growth studies of Bacilli strains GB03 and IN937a revealed that the volatile components 2,3-butanediol and acetoin trigger plant growth promotion in Arabidopsis. Differences in growth promotion when cytokinin-signaling mutants are exposed to GB03 versus IN937a volatiles suggest a divergence in chemical signaling for these two bacterial strains. To provide a comprehensive chemical profile of bacterial volatiles emitted from these biologically active strains, headspace solid phase microextraction (SPME) coupled with software extraction of overlapping GC-separated components was employed. Ten volatile metabolites already reported from GB03 and IN937a were identified as well as 28 compounds not previously characterized. Most of the newly identified compounds were branched-chain alcohols released from IN937a, at much higher levels than in GB03. Principal component analysis clearly separated GB03 from IN937a, with GB03 producing higher amounts of 3-methyl-1-butanol, 2-methyl-1-butanol and butane-1-methoxy-3-methyl. The branched-chain alcohols share a similar functional motif to that of 2,3-butanediol and may afford alternative structural patterns for elicitors from bacterial sources.     

Optimization of microwave-assisted extraction followed by solid phase micro extraction and gas chromatography-mass spectrometry detection for the assay of some semi volatile organic pollutants in sebum

Methodology using MAE/SPME/GC-MS is being pursued for the analysis of organic pollutants in sebum. The microwave-assisted extraction (MAE) of standards of semi volatile organic pollutants from sebum was optimized. All compounds were extracted from sebum with recoveries analyzed by GC/MS ranging from 94% to 100% under the optimum MAE conditions: 10mL acetone-hexane (2:1), 60 degrees C, and 10 min microwave heating. To improve the detection limits a SPME procedure was optimized. Linearity ranged from 0.70 ppb to 25 ppb. R.S.D. were in the range of 1-23% for the SPME step. Preliminary real samples were analyzed and a range of compounds was detected. The optimized MAE/SPME/GC-MS methodology promises to be useful for different applications.     

Biological degradation of diesel fuel in water and soil monitored with solid-phase micro-extraction and GC-MS

Solid-phase micro-extraction (SPME) was used for monitoring degradation of hydrocarbons in diesel-fuel-contaminated (1% v/v) water and soil. Natural soil bacteria with and without external addition of inoculum were used. Directly after a 10-s exposure of the sample, the polydimethylsiloxane fibre was injected into the GC-MS. This method strongly reduced the time of analysis compared to a conventional liquid/liquid extraction. A comparison of SPME and pentane extraction of diesel oil was made and found to be consistent. The degradation of diesel fuel in water was monitored for 10 weeks using SPME. After 5 weeks all hydrocarbons were degraded except for the decahydronaphthalenes. These compounds were approximately 3% of the total hydrocarbons in the diesel oil used and remained undegraded throughout the study although none of the chemical or physical parameters was limiting. In the soil study the degradation of diesel fuel in normal soil was completed after 3 weeks, when the only remaining substances were decahydronaphthalenes. All samples were compared to sterile references to make up for evaporation losses. SPME proved to be a fast and reliable method to monitor changes in concentrations of semi-volatile organic compounds. Received: 23 December 1997 / Received revision: 5 February 1998 / Accepted: 27 February 1998     

Volatile compounds of the green alga, Capsosiphon fulvescens

Essential oils extracted by static vacuum simultaneous distillation–extraction (V-SDE) and conventional SDE from a green alga, Capsosiphon fulvescens, were analyzed by gas chromatography (GC) and GC-mass spectrometry. The essential oil extracted with V-SDE and SDE has totals of 151 and 140 compounds, respectively. A combined total of 208 compounds were identified and 81 volatiles were common in both extracts. These included 8 acids, 28 alcohols, 34 aldehydes, 11 esters, 25 ketones, 19 aliphatic hydrocarbons, 43 branched hydrocarbons, 6 unsaturated hydrocarbons, 19 cyclic hydrocarbons, and 15 miscellaneous. The major volatile compounds of the oil extracted with V-SDE were (E)-β-ionone, octane, (E,E)-2,4-heptadienal, hexadecanoic acid, and β-cyclocitral, while those extracted with SDE were hexadecanoic acid, (Z,Z)-1,5-octadien-3-ol, tetradecanoic acid, (E,E)-2,4-heptadienal, and benzaldehyde. The characteristics of the flavor of the green alga might be contributed by the presence of a large number of aldehydes and ketones. Many of the compounds extracted with SDE might originate from thermal degradation and/or thermal interactions among the constituents in the alga during steam distillation.     

Volatile compounds emitted by live European honey bee (Apis mellifera L.) queens

We used solid-phase microextraction (SPME, 65 microm PDMS-DVB fiber) to sample the volatile compounds emitted by live honey bee queens in several reproductive states (unmated queens, recently mated queens, and established mated queens), and compared them to the volatiles emitted by workers. We detected nine compounds that were present in at least 75% of the individuals in at least one type of bee, and which were not present in the sampling environment alone. Four of these compounds were present in queens but not in workers. One of these four compounds, identified as E-beta-ocimene, was expressed fully only in established mated queens and may be a signal of diploid egg-laying activity. The three remaining queen-specific compounds (including one identified as 2-phenylethanol) were associated with unmated queens and may mediate interactions between unmated queens and workers during queen elimination. The five common compounds that we detected in both queens and workers were hydrocarbons and may function as nestmate recognition cues. We consider these discoveries as a first step in determining the potentially important functions of volatile signals and cues within honey bee nests.     

Studies on the aroma of maté (Ilex paraguariensis St. Hil.) using headspace solid-phase microextraction

Volatile and semi-volatile components of maté (Ilex paraguariensis St. Hil.) were analysed by headspace solid-phase microextraction (HS-SPME) coupled to gas chromatography and mass spectrometry. Five SPME fibres coated separately with 100 microm poly(dimethylsiloxane) (PDMS), 65 microm PDMS-divinylbenzene (DVB), 70 microm carbowax (CW)-DVB, 85 microm carboxen (CAR)-PMDS or 50/30 microm DVB-CAR, were tested. Seventy compounds were identified in the sample headspace, including propanal, (E)-2-pentenal, hexanal, (E)-2-hexenal, 6-methyl-5-hepten-2-one, (E,Z)-2,4-heptadienal, (E,E)-2,4-heptadienal, (E,Z)-3,5-octadien-2-one, beta-cyclocitral, 3-ethyl 4-methyl-(1H)-pyrrole-2,5-dione, alpha-ionone, geranylacetone, beta-ionone, dihydroactinidiolide and caffeine. Extraction parameters such as temperature, time and sample mass were studied and optimized. The best conditions for trapping volatile and semi-volatile compounds were obtained using a DVB-CAR fibre at 80 degrees C for 60 min with a sample mass starting from 100 mg in a vial of 4 mL.     

Development of a Headspace Solid‐Phase Microextraction Gas Chromatography‐Mass Spectrometry Method to Study Volatile Organic Compounds (VOCs) Emitted by Lavender Roots

A headspace solid‐phase microextraction (HS‐SPME) method combined with gas chromatography‐mass spectrometry (GC/MS) was developed and optimized for the extraction and the analysis of volatile organic compounds (VOCs) from lavandin and fine lavender roots. Optimal parameters to extract volatile molecules from ground and intact roots were determined using a divinylbenzene‐carboxen‐polydimethylsiloxane (DVB/CAR/PDMS) coating fiber at 70 °C for 60 min. A total of 99 VOCs, including 40 monoterpenoids, 15 sesquiterpenoids, 1 diterpenoid and 2 coumarins were detected. The main compounds detected in lavandin roots were fenchol, borneol, and coumarin. Performances of the optimized SPME GC/MS method were evaluated via the comparison of VOC emissions between roots from different cultivars of fine lavender (7713 and maillette) and lavandin (abrial and grosso). Chemometric analysis, using partial least squares‐discriminant analysis (PLS‐DA), suggests fifteen significant features as potential discriminatory compounds. Among them, β‐phellandrene allows discrimination between lavender and lavandin varieties.     

Headspace solid-phase microextraction gas chromatography–mass spectrometry analysis of Eupatorium odoratum extract as an oviposition repellent

Headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography–mass spectrometry (GC–MS) analysis was used to study volatile and semi-volatile compounds emitted by the Eupatorium odoratum (E. odoratum) extract. Variables of HS-SPME such as the type of SPME fiber, extraction time and temperature, incubation time, desorption time and temperature have been optimized. Optimized conditions were obtained by the use of divinylbenzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS) fiber, 5 min/20 min incubation/extraction time at 65 °C, 5 min desorption time at 260 °C. Using three different polar chromatographic columns to get retention index and mass spectrometry data, 99 volatile and semi-volatile compounds were tentatively identified in the E. odoratum extract. This study has identified the promising source of E. odoratum oviposition repellent.     

Solid-phase microextraction (SPME) analysis of six Italian populations of Ephedra nebrodensis Tineo ex Guss. subsp. nebrodensis

Headspace solid-phase microextraction (HS-SPME) coupled with GC/FID and GC/MS was applied for the first time in the analysis of the volatile fraction of an Ephedra species. Notably, six Italian populations (Marche, Abruzzo, and Sardinia) of Ephedra nebrodensis subsp. nebrodensis, covering almost the entire Italian area, were investigated to examine the chemical variability and to support the taxonomy of the species. A fiber screening with polymethylsiloxane (PDMS), Carboxen(TM) /polymethylsiloxane (CAR/PDMS), and polymethylsiloxane/divinylbenzene (PDMS/DVB) coatings, together with an optimization of the extraction conditions were carried out before analysis of the six populations. A total of 119 volatiles were identified in the headspace of different samples, accounting for 63.35-100.00% of the total volatiles. A great variability was found in the qualitative composition of different samples, since only 18 components were in common among all populations. The headspace composition was dominated by sesquiterpene hydrocarbons (52.30-88.32%), with β-maaliene (traces-7.49%), β-patchoulene (traces-1.29%), β-panasinsene (traces-6.85%), α-isocomene (traces-31.25%), α-trans-bergamotene (traces-6.95%), alloaromadendrene (traces-33.20%), α-acoradiene (traces-9.41%), and γ-muurolene (0.61-16.33%) being the most abundant constituents. Noteworthy is the occurrence in a sample of two major unknown sesquiterpenes, one hydrocarbon (24.49%, RI: 1396) and one oxygenated compound (10.37%, RI: 1591), whose mass spectra were reported for the first time. Multivariate chemometric techniques, such as cluster analysis (CA) and principal component analysis (PCA), were used to characterize the samples according to the geographical origin.     

采用多次顶空固相微萃取分析拟南芥绿叶挥发性物质

顶空固相微萃取作为一种新的挥发性和半挥发性物质分析技术,被广泛应用于植物样品的定性分析。由于进行顶空分析时,挥发性组分间的基质效应以及较为复杂的扩散和吸附过程,定量分析一直是SPME分析应用的难题。目标分析物的量看作是达到吸附平衡后单一萃取的物质量的总和,则无需考虑分析样品在顶空、萃取涂层间的分配,同时可以消除基质效应。在利用标准物质进行校正后只需要一次顶空萃取,即可求出分析物质的总量。首先利用DVB/CAR/PDMS定性得到拟南芥挥发性物质的组成,然后采用CAR/PDMS涂层定量,分析了拟南芥的3种绿叶挥发性物质,优化后萃取条件为40℃萃取20min,相对标准偏差小于12%,在3株植物样品中这些挥发性物质的量为78.6~158.4ng.g-1。     

Oviposition induced volatiles in tomato plants

In response to attack by herbivorous insect, plants produce semiochemicals which act to attract their natural enemies. Recent work on plant volatile compounds has shown that they may play multiple roles as communication signals and defense agents. Here we measured the volatile profile of tomato plants with and without oviposition by the herbivore moth, Tuta absoluta. We used solid phase micro extraction (SPME) sample pre-concentration techniques combined with gas chromatography-mass spectrometry. We have found that different volatile profiles emitted from tomato plants with oviposition by T. absoluta compared to control plants. Hexanal, (Z)-3-hexen-1-ol and an unidentified compound were isolated only from tomato plants with T. absoluta eggs. (Z)-3-hexen-1-ol was identified only from tomato plants with T. absoluta eggs that were laid three days earlier. The percentage of sesquiterpenes (e.g. δ-elemene) has been found to increase in the headspace of tomato plants with oviposition. These results in respect to indirect defense of tomato plants to T. absoluta are discussed.     

香茅草产香内生真菌的筛选及香气成分分析

从香料植物香茅草(Cumbopogon citratus (DC．)stapf)分离到31株内生真菌,进行液体发酵,有1株产生香味物质,这株菌的发酵提取物采用同时蒸馏萃取装置收集挥发性成分,并用气相色谱/质谱仪对其香味成分进行分离鉴定,共检出74种化合物,其中有乙缩醛二乙醇、柠檬烯、月桂烯、月桂醛等多种香料物质。     

三种固相微萃取头对厚皮甜瓜果汁香气成分萃取效果分析

采用美国Supelco公司生产的Carboxen^TM/PDMS、DVB/CAR/PDMS和PDMS/DVB 3种固相微萃取头萃取厚皮甜瓜(Cucumis melo L.)果汁中的香气成分,并用气质联用仪对香气成分进行检测。结果表明, 3种萃取头检测到的香气成分均以酯类为主,醇类和醛类较少。Carboxen^TM/PDMS萃取的香气成分相对含量达91.55%,特征香气成分相对含量达到63.01%;DVB/CAR/PDMS也可以全面萃取甜瓜香气,但香气成分与特征香气的相对含量及总峰面积比Carboxen^TM/PDMS的低;PDMS/DVB萃取头吸附的香气成分种类最少,相对含量最低。可见,对厚皮甜瓜果汁香气成分的萃取以Carboxen^TM/PDMS萃取头较好。     

Analysis of Rhioxma Curcumae Aeruginosae volatiles by solid-phase microextraction with gas chromatography-mass spectrometry

In this paper, a headspace solid-phase microextraction (HS-SPME) method was applied to analyse the volatile compounds in a traditional Chinese medicine (TCM), Rhioxma Curcumae Aeruginosae. SPME parameters such as fibers, extraction temperature, extraction time and desorption time were investigated. Thirty-five volatile compounds were separated and identified. Relative standard deviations (RSDs) were less than 8.4%, showing that the method has a good reproducibility. The volatile constituents were also analyzed by steam distillation (SD) and thirty-seven compounds were identified. The similar results obtained by the two methods showed that SPME is a good alternative for the analysis of volatile constituents in Rhioxma Curcumae Aeruginosae samples and it is a relatively simple, rapid and solvent-free method.     

Rapid determination of volatile compounds emitted from Chimonanthus praecox flowers by HS-SPME-GC-MS

A novel rapid, simple and solvent-free method was developed for determination of the volatile compounds from the flowers of Chimonanthus praecox Link using headspace solid-phase microextraction (HS-SPME) and gas chromatography-mass spectrometry (GC-MS). The SPME conditions were firstly optimized and applied to sampling of the volatile compounds emitted from living Chimonanthus praecox L. flowers and excised Chimonanthus praecox L. flowers. Thirty-one compounds emitted from living flowers were identified for the first time, which mainly included 4-methyl-1,3-pentadiene (2.0%), a-phellandrene (4.7%), benzyl methanol (11.1%), trans-linalool oxide (furanyl ring) (5.3%), a-linalool (36.0%), methyl salicylate (24.5%) and acetic acid benzyl ester (5.9%). Comparing the emission from living flowers and excised flowers, twenty-eight compounds were found to be detected in the two emissions, and three compounds, n-pentadecane, n-cetane and n-heptadecane, were only found in the emission from the living flowers, which shows that they might be biomarker compounds.