			Home About us Contact

Headspace Solid-phase Microextraction (headspace + solid-phase_microextraction)

Distribution by Scientific Domains

Chemistry	77%
Life Sciences	22%

Selected Abstracts

Screening of Volatile Composition of Lavandula hybridaReverchon II Honey Using Headspace Solid-Phase Microextraction and Ultrasonic Solvent Extraction

CHEMISTRY & BIODIVERSITY, Issue 3 2009
Igor Jerkovi
Abstract The volatiles of unifloral Lavandula hybridaReverchon II honey were isolated by means of headspace solid-phase microextraction (HS-SPME) and ultrasonic solvent extraction (USE) and analyzed by gas chromatography and mass spectrometry (GC, GC/MS). A total of 23 compounds were identified in the headspace with hexan-1-ol, hexanal, acetic acid, hotrienol, and 2-phenylacetaldehyde as the principal components. Three solvents of different polarity were used for USE, and a total of 53 compounds were identified. The extracts with pentane/Et2O 1,:,2 (v/v) were the most representative for USE method containing the majority of the honey floral origin compounds and potential biomarkers (hexanol, acetic acid, butane-1,3-diol, butane-2,3-diol, benzoic acid, coumarin, and 2-phenylacetic acid). The total number of identified compounds (USE and HS-SPME) was 59. In general, the comparison with volatiles of other lavandin honeys of different geographic origins indicated several similarities, while acetic and formic acids were identified with high percentages in L. hybridaReverchon II honey. [source]

Characterization of volatile compounds and triacylglycerol profiles of nut oils using SPME-GC-MS and MALDI-TOF-MS

EUROPEAN JOURNAL OF LIPID SCIENCE AND TECHNOLOGY, Issue 2 2009
Stefanie Bail
Abstract Several nut oil varieties mainly used as culinary and overall healthy food ingredients were subject of the present study. Headspace solid-phase microextraction combined with gas chromatography-mass spectrometry was employed in order to determine the qualitative composition of volatile compounds. Furthermore, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry was used in order to assess the profiles and relative composition of the prevalent triacylglycerols (TAG) within the oils. The headspace of the majority of oil samples was dominated by high contents of acetic acid (up to 42%) and hexanal (up to 32%). As nut oils are typically gained by cold-pressing from previously roasted nuts, characteristic pyrazine derivatives as well as degradation products of long-chain fatty acids were detected. TAG analysis of these oils revealed a quite homogeneous composition dominated by components of the C52 and C54 group composed mainly of oleic (18:1), linoleic (18:2), stearic (18:0) and palmitic (16:0) acid residues representing together between 65 and 95% of the investigated nut oils. The TAG profiles showed characteristic patterns which can be used as ,fingerprints' of the genuine oils. Nut oils exhibiting quite similar fatty acid composition (e.g. hazelnut, pistachio and beech oil) could be clearly discriminated based on TAG showing significant differences between the oils. [source]

Headspace solid-phase microextraction for direct determination of volatile phenols in cider

JOURNAL OF SEPARATION SCIENCE, JSS, Issue 21 2009
Consuelo Pizarro
Abstract A headspace solid-phase microextraction coupled to gas chromatography-tandem mass spectrometry (GC-MS/MS) method was optimised and validated for the determination of 4-ethylguaiacol, 4-ethylphenol, 4-vinylguaiacol and 4-vinylphenol, involved in the presence of Brett character, in ciders. The influence of different parameters on extraction efficiency (fibre coating, salt addition, exposure time, extraction temperature and sample volume/total volume ratio) was evaluated. Divinylbenzene/carboxen/PDMS was selected as extraction fibre and the other optimised parameters were as follows: 10,mL of cider, temperature 70°C, extraction time 60,min and addition of 0.4,g/mL of NaCl. The proposed method showed satisfactory linearity. The detection limits obtained were 0.01,,g/L for 4-ethylguaiacol, 0.02,,g/L for 4-ethylphenol, 0.08,,g/L for 4-vinylguaiacol and 0.03,,g/L for 4-vinylphenol. These detection limits were lower than those obtained in previous studies on the determination of volatile phenols in other alcoholic beverages. Good recoveries of over 95% were observed for all compounds, and the repeatability obtained was considered acceptable, ranging between 4 and 10%. To demonstrate the feasibility of the procedure, the method was applied to the analysis of commercial ciders. To our knowledge, this is the first time that the headspace solid-phase microextraction procedure has been optimised to determine specifically the Brett character responsible compounds in cider. [source]

Optimisation of the headspace-solid phase microextraction for organomercury and organotin compound determination in sediment and biota

JOURNAL OF SEPARATION SCIENCE, JSS, Issue 4 2008
Alejandra Delgado
Abstract Headspace solid-phase microextraction was optimised for the simultaneous preconcentration of methylmercury (MeHg+), monobutyltin, dibutyltin, tributyltin, monophenyltin (MPhT), diphenyltin (DPhT), and triphenyltin (TPhT) from sediments and biota. Extraction time (3,24 min), extraction temperature (20,90°C), desorption time (1,10.4 min), desorption temperature (152,260°C), and sample volume (5,22 mL) were simultaneously optimised, while variables such as fibre type (30 ,m polydimethylsiloxane, PDMS), pH (acetic acid/sodium acetate, HOAc/NaOAc, 2 mol/L, pH , 4.8), the concentration of the derivatisation agent (sodium tetraethylborate, NaBEt4, 0.1% m/v), and the ionic strength (fixed by the buffer solution) were kept constant. The variables were optimised according to the experiments proposed by the MultiSimplex program and the responses were considered in order to establish the optimum conditions. The repeatability (relative standard deviation, RSD, 5,20.6%) and limits of detection (LODs, 0.05,0.97 ng/g) of the overall method were also estimated. The lowest precisions were obtained for DPhT and TPhT. The optimised preconcentration method was applied to the determination of MeHg+, butyl- and phenyltins in certified reference materials (IAEA-405 MeHg+ in estuarine sediment, BCR-646 butyl- and phenyltins in marine sediment, BCR-463 MeHg+ in tuna fish, DOLT-2 MeHg+ in dogfish liver, and BCR-477 butyltins in mussel tissue) by GC with microwave-induced plasma/atomic-emission detection. [source]

Measurement of Henry's law constant for methyl tert -butyl ether using solid-phase microextraction

ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 8 2001
Britta G. Bierwagen
Abstract Increasing groundwater contamination with methyl tert -butyl ether (MTBE) requires more efficient remediation technologies. Accurate measurement of MTBE's air,water partitioning coefficient (Henry's law constant, H) is important for the design and optimization of removal efficiency for many treatment systems as well as for predicting its fate and transport. Previously published data for MTBE appear to have some unusual nonlinearity at lower temperatures (15,30°C), and a wide range of values exists for dimensionless H at 25°C, from 0.0216 to 0.1226 in the published literature. We measured H for MTBE using headspace solid-phase microextraction (SPME) and a static method that considers equilibrium partitioning in a closed system, for temperatures between 15 and 40°C. To validate our methods, we measured H for benzene, toluene, and trichloroethylene and compared our results to previously published values, with excellent agreement. The Arrhenius plot for MTBE indicates that ln(HMBTE) = 6.85,2,900 T,1, with T in K. At 25°C, HMBTE = 0.0555 ± 0.0122. [source]

Variation in 4-mercapto-4-methyl-pentan-2-one release by Saccharomyces cerevisiae commercial wine strains

FEMS MICROBIOLOGY LETTERS, Issue 2 2004
Kate S. Howell
Abstract The volatile thiol 4-mercapto-4-methylpentan-2-one (4MMP) is a potent contributor to wine aroma. In grape juice, 4MMP is bound to cysteine as a non-volatile compound and requires the action of yeast during fermentation to release the aroma active thiol. A method was developed to measure 4MMP release from the precursor by headspace solid-phase microextraction and separation by gas chromatography with atomic emission detection to screen the ability of wine yeast to release 4MMP. Yeast commonly used in white wine making were grown with the precursor at two different temperatures, and the amount of 4MMP released was measured. The results demonstrate that yeast strain selection and fermentation temperature can provide an important tool to enhance or modulate the grape-derived aromas formed during wine fermentation. [source]

Determination of thiol compounds by automated headspace solid-phase microextraction with in-fiber derivatization

FLAVOUR AND FRAGRANCE JOURNAL, Issue 3 2006
Qing Wang
Abstract In this article, headspace solid-phase microextraction (HS-SPME) analysis of thiol compounds with both solid and aqueous samples was investigated using N -phenylmaleimide as an in-fiber derivatization reagent. The derivatives were analyzed using GC-MS. The HS-SPME method was executed on an automatic sampler and optimized by studying a variety of factors such as the selection of the fiber, extraction time, temperature, agitation speed, etc. Method validation was carried out by spiking known amounts of thiol compounds into the sample and calculating the concentration by standard addition. The relative standard deviations (RSD) for the majority of the thiols were less than 10%. The developed method resulted in a limit of detection (LOD) in the low microgram per liter for most of the thiols analyzed, which was about one order of magnitude lower than the HS-SPME without derivatization. Finally, the overall method was successfully applied for the determination of thiols in yellow onion, green onion and garlic. Copyright © 2006 John Wiley & Sons, Ltd. [source]

PHYSICOCHEMICAL AND FLAVOR CHANGES OF FRAGRANT BANANA (MUSA ACUMINATA AAA GROUP "GROSS MICHEL") DURING RIPENING

JOURNAL OF FOOD PROCESSING AND PRESERVATION, Issue 3 2010
SOMRUEDEE THAIPHANIT
ABSTRACT The objective of this research was to characterize the physicochemical and flavor changes that occur in ripe Hom Thong (Musa acuminata AAA Group "Gross Michel") flesh at stage 6,8. It was found that the higher fresh maturity stage of Hom Thong at P < 0.05 has the following results: the antioxidant activities, moisture content and reducing sugar are significantly increased. The titratable acidity, total soluble solid and prebiotic activities' score for Lactobacillus acidophilus LA5 and Bifidobacterium lactis BB-12 are significantly decreased. The total dietary fiber remains unchanged. Using headspace solid-phase microextraction and gas chromatography,mass spectrometry to characterize volatile compound found that the flavor 20 volatile compounds (11 esters, 5 alcohols, 3 carbonyls and 1 ketone) are varied on Hom Thong maturity stage. The compounds with the most aroma impact for ripe Hom Thong flesh at stage 6,8 were 3-methylbutyl butanoate, 3-methyl-1-butyl acetate, 3-methylbutyl 3-methylbutanoate and 2-methylpropyl ethanoate. PRACTICAL APPLICATIONS Ripe banana Musa acuminata, AAA Group "Gross Michel," locally known in Thailand as Hom Thong, is a popular food item consumed as fruit, snacks or food ingredients for confections, spreads and other banana products. Using a suitable ripening stage of the banana flesh is the most critical step among many steps of unit operations for achieving high-quality banana products. This study not only characterizes the physicochemical and flavor changes that occur in ripe Hom Thong flesh at stage 6,8, but also studies antioxidant activities and prebiotic activities. Manufacturers can utilize the data presented in this article to select the suitable ripening stage in order to avoid product failure and to produce the best quality products for functional food, pharmafood, medifood or vitafood that are rich in natural banana flavor. [source]

Determination of eight fatty acid ethyl esters in meconium samples by headspace solid-phase microextraction and gas chromatography,mass spectrometry

JOURNAL OF SEPARATION SCIENCE, JSS, Issue 14 2010
Marli Roehsig
Abstract A number of fatty acid ethyl esters (FAEEs) have recently been detected in meconium samples. Several of these FAEEs have been evaluated as possible biomarkers for in utero ethanol exposure. In the present study, a method was optimized and validated for the simultaneous determination of eight FAEEs (ethyl laurate, ethyl myristate, ethyl palmitate, ethyl palmitoleate, ethyl stearate, ethyl oleate, ethyl linoleate and ethyl arachidonate) in meconium samples. FAEEs were extracted by headspace solid-phase microextraction. Analyte detection and quantification were carried out using GC-MS operated in chemical ionization mode. The corresponding D5-ethyl esters were synthesized and used as internal standards. The LOQ and LOD for each analyte were <150 and <100,ng/g, respectively. The method showed good linearity (r2>0.98) in the concentration range studied (LOQ , 2000,ng/g). The intra- and interday imprecision, given by the RSD of the method, was lower than 15% for all FAEEs studied. The validated method was applied to 63 authentic specimens. FAEEs could be detected in alcohol-exposed newborns (>600,ng/g cumulative concentration). Interestingly, FAEEs could also be detected in some non-exposed newborns, although the concentrations were much lower than those measured in exposed cases. [source]

Headspace solid-phase microextraction for direct determination of volatile phenols in cider

Analysis of aldehydes via headspace SPME with on-fiber derivatization to their O -(2,3,4,5,6-pentafluorobenzyl)oxime derivatives and comprehensive 2D-GC-MS

JOURNAL OF SEPARATION SCIENCE, JSS, Issue 19 2008
Hans-Georg Schmarr
Abstract A method for the analysis of the homologous series of alkanals, (E)-2-alkenals, and (E,E)-2,4-alkadienals is described utilizing a headspace solid-phase microextraction (HS-SPME) step and on-fiber derivatization with O -(2,3,4,5,6-pentafluorobenzyl)hydroxylamine (PFBHA) hydrochloride. Oxime derivatives formed on the fiber are desorbed in the gas chromatographic injector and analyzed by comprehensive 2-D GC coupled to quadrupole MS (GC×GC-qMS). Selecting specific fragment ions within the electron impact mass spectra of the oxime derivatives provides a suitable method for the target analysis of these aldehyde classes, which furthermore benefits from the increased separation efficiency by GC×GC. The analysis of higher molecular weight aldehydes is described in wine and grape seed oil as examples. Quantification of the aldehydes utilizes a stable isotope dilution analysis (SIDA) assay with octan-d16 -al as isotopomeric internal standard. Besides the selectivity and sensitivity of aldehyde analysis using PFBHA derivatives, critical aspects on background level contamination and repeatability of the sample preparation method are discussed. Optimization of GC×GC-qMS parameters allowed a considerable saving of the cryogenic medium, involving additional (unmodulated) conditioning runs, rendering the method more amenable to routine analysis. [source]

Sampling flower scent for chromatographic analysis

JOURNAL OF SEPARATION SCIENCE, JSS, Issue 11 2008
Elena E. Stashenko
Abstract The analysis of flower volatiles requires special methods for their isolation with enrichment. Living flowers show a continuous change in their volatile profile that depends on intrinsic (genetic) and external (light, temperature, hydric stress) factors. Excised flowers suffer rapid deterioration and loss of volatiles. While industrial isolation methods for flower volatiles are well established, those at the laboratory-scale experience progressive development, in the search for higher sensitivity, reproducibility, and simplicity. This review covers the flower scent sampling methods most commonly employed during the last decade, and includes comments on their strengths and limitations. The strengths of headspace solid-phase microextraction (HS-SPME) for in vivo monitoring are emphasized with the examples of monitoring the circadian variation of Brugmansia suaveolens flower scent and of volatile aldehyde detection in flower scent using on-fiber derivatization. [source]

Rapid differentiation of new apple cultivars by headspace solid-phase microextraction in combination with chemometrical data processing

MOLECULAR NUTRITION & FOOD RESEARCH (FORMERLY NAHRUNG/FOOD), Issue 2 2003
Ines Schulz
Abstract The aim of this study was to test a combination of automated headspace solid phase-microextraction gas chromatography (GC) with chemometrical data treatment for the rapid differentiation of enzyme-inactivated homogenates of new apple cultivars. The four cultivars Pinova, Piflora, Renora and Florina are characterized by different volatile patterns. Differences in the contents of volatiles were especially found for butyl acetate, ethyl butanoate, 2-methyl butanol, ethyl acetate and 6-methyl-5-hepten-2-ol. The used sample preparation method for GC coupled with pattern recognition of chromatograms is a useful tool for rapid and reliable determination of large numbers of samples. [source]

Determination of diisopropylfluorophosphate in rat plasma and brain tissue by headspace solid-phase microextraction gas chromatography/mass spectrometry

RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 19 2008
Meng Xu
A simple, sensitive and rapid method for the determination of diisopropylfluorophosphate (DFP) in rat plasma and brain tissue using headspace solid-phase microextraction (HS-SPME) and gas chromatography/mass spectrometry (GC/MS) is presented. A 65,µm polydimethylsiloxane/divinylbenzene (PDMS/DVB) fiber was selected for sampling. The main parameters affecting the SPME process such as extraction and desorption temperature, extraction and desorption time, salt addition, and fiber preheating time were optimized in each matrix to enhance the extraction efficiency of the method. The lower limits of quantitation for DFP in plasma and brain tissue were 1,ng/mL and 3,ng/g, respectively. The method showed good linearity over the range from 1,100,ng/mL in plasma and 3,300,ng/g in brain tissue with correlation coefficient (R2) values higher than 0.995. The precision and accuracy for intra-day and inter-day were less than 10%. The relative recoveries in plasma and brain for DFP were greater than 50%. Stability tests including autosampler and freeze and thaw were also investigated. This validated method was successfully applied to study the neurobehavioral effects of low-level organophosphate exposures. Copyright © 2008 John Wiley & Sons, Ltd. [source]

Fragrant Volatile Compounds in the Liverwort Drepanolejeunea madagascariensis (Steph.) Grolle: Approach by the HS-SPME Technique

CHEMISTRY & BIODIVERSITY, Issue 3 2010
Anne Gauvin-Bialecki
Abstract Three populations of the epiphyllous liverwort Drepanolejeunea madagascariensis collected in the cloud forests of Reunion Island (Mascarene Archipelago) were investigated for their volatile compounds, because of the pleasant, sweet, warm, woody-spicy, and herbaceous fragrance, slightly reminiscent of dill, of this species. By applying the headspace solid-phase microextraction (HS-SPME) technique coupled to GC/MS analysis, 34 compounds were detected in total, with p -menth-1-en-9-ol (28.8,43.5%), limonene (10.5,14.7%), , -phellandrene (8.8,11.6%), and the so-called dill ether (8.5,16.6%) as the main components. The presence of 1-epi- , -pinguisene confirms the possible use of pinguisane-type sesquiterpenoids as a characteristic chemical marker for the order Jungermanniales. [source]