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Results for “Solid Phase Microextraction”

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PubMed2005

Transport and fate of dieldrin in poplar and willow trees analyzed by SPME.

Dieldrin is a hydrophobic organochlorine insecticide that is persistent in the environment. The fate and transport of dieldrin in trees is important both in the context of potential remediation, as well as food chain impacts through dieldrin transport to shoots and leaves. Experiments were conducted to measure the degree of dieldrin partitioning to plant tissue and the potential for biodegradation of dieldrin in the microbe rich tree rhizosphere. Dieldrin was analyzed in water and plant tissue using headspace solid-phase microextraction (SPME) coupled with gas chromatography. Poplar and willow saplings planted in soil and watered with 10 microgl(-1) dieldrin for up to 9 months showed no adverse effects due to dieldrin exposure and no dieldrin was observed in plant shoots with a method detection limit (MDL) of 7 ngg(-1). One-week hydroponic tests of poplar saplings exposed to aqueous dieldrin also showed no detection of dieldrin in shoots, with an average of 66% of the dieldrin partitioned to the plant roots and an overall mass balance recovery of 76% in the plant-water system. The root concentration factor (RCF) was found to be 30+/-3 ml water g(-1) root. Biodegradation of dieldrin was not observed in an aqueous batch bioreactor containing 8 microgl(-1) dieldrin, nutrients and bacteria from the root zone of a poplar sapling that had been exposed to dieldrin for 9 months. These results show that planting trees is likely to be safe and potentially useful at sites containing low-levels of dieldrin in groundwater.

Biodegradation, Environmental↗

PubMed2006

Photolytic degradation of quinalphos in natural waters and on soil matrices under simulated solar irradiation.

The photochemical persistence of quinalphos, one of the most widely used organophosphorous insecticides, was investigated in a variety of environmental matrices such as natural waters and soils of different composition. Simulated solar irradiation was obtained using a xenon arc lamp (Suntest CPS+ apparatus) giving an irradiation intensity of 750 W m(-2) equivalent to a light dose per hour of irradiation of 2,700 kJ m(-2). The phototransformation rates were determined using solid-phase microextraction (SPME) and ultrasonic extraction (USE) coupled to GC-FTD, while the identification of photoproducts was carried out by GC-MS. In water samples, the degradation kinetics followed a pseudo-first-order reaction and photolysis half-lives ranged between 11.6 and 19.0 h depending on the constitution of the irradiated media. Dissolved organic matter (DOM) has a predominant retarding effect, while nitrate ions accelerated the photodegradation kinetics. In soil samples, the degradation kinetics was monitored on 1mm soil layer prepared on glass TLC plates. The kinetic behaviour of quinalphos was complex and characterized by a double step photoreaction, fast in the first 4h of irradiation followed by a slow degradation rate up to 64 h. The photolysis half-life of quinalphos was shorter in sandy soil compared to the rest of the soil samples, varying between 16.9 and 47.5 h, and showing a strong dependence on the composition of the irradiated media. Among the transformation products formed mainly through photohydrolysis and photoisomerization processes, some photoproduct structures were proposed according to their mass spectral information.

Chromatography, Gas↗

PubMed2006

Study of metabolites from the degradation of polycyclic aromatic hydrocarbons (PAHs) by bacterial consortium enriched from mangrove sediments.

The PAH metabolites produced during degradation of fluorene, phenanthrene and pyrene by a bacterial consortium enriched from mangrove sediments were analyzed using the on-fiber silylation solid-phase microextraction (SPME) combining with gas chromatography-mass spectrometry (GC-MS) method. Seventeen metabolites at trace levels were identified in different PAH degradation cultures based on the full scan mass spectra. In fluorene degradation cultures, 1-, 2-, 3- and 9-hydroxyfluorene, fluorenone, and phthalic acid were detected. In phenanthrene and pyrene degradation cultures, various common metabolites such as phenanthrene and pyrene dihydrodiols, mono-hydroxy phenanthrene, dihydroxy pyrene, lactone and 4-hydroxyphenanthrene, methyl ester, and phthalic acid were found. The detection of various common and novel metabolites demonstrates that SPME combining with GC-MS is a quick and convenient method for identification as well as monitoring the real time changes of metabolite concentrations throughout the degradation processes. The knowledge of PAH metabolic pathways and kinetics within indigenous bacterial consortium enriched from mangrove sediments contributes to enhance the bioremediation efficiency of PAH in real environment.

Bacteria↗

PubMed2006

Evaluating the impacts of some environmentally relevant factors on the availability of bisphenol A with negligible-depletion SPME.

The effect of some environmentally relevant factors including salinity, pH, and humic acids on the availability of bisphenol A (BPA) was evaluated by using the negligible-depletion solid-phase microextraction (nd-SPME) biomimetic method. With the variation of salinity (0-500 mM NaCl) and pH (5.0-8.5) of aqueous solutions, the partition coefficients of BPA between the nd-SPME fiber and the aqueous solution varied in the range of logD=3.55-3.86, which indicates that the salinity and pH can influence the availability of BPA. By using Acros humic acid as model dissolved organic matter (DOM), it was also demonstrated that the environmental factors such as salinity and pH could affect the partitioning of BPA between DOM and aqueous solutions. The determined partition coefficients of BPA between dissolved organic carbon (DOC) and aqueous solutions were in the range of logD(DOC)=4.03-5.60 for Acros humic acid solutions with 1-50 mg l(-1) DOC. The influence of salinity and pH on logD(DOC) was more significant at low concentration (0-5 mg l(-1)) of DOC.

Benzhydryl Compounds↗

PubMed2003

Guidelines for capillary extraction-capillary gas chromatography: preparation of extractors and analysis of aromatic compounds in water.

The benzene, toluene, ethylbenzene and xylenes system (BTEX) in clean water is studied to verify the performance of capillary extraction as an extraction-preconcentration technique well hyphenated with GC. The approach uses pieces of coated capillaries usually 5-30 cm long, trimmed from customary high-resolution GC columns but carrying glass press-fits at their ends. The preparation of these 'capillary extractors' is explained, and their performance is discussed providing guidelines for use. Injection by capillary extraction is such that (i) band broadening in time is null, and (ii) band broadening in space cannot be higher than the extractor length. Speed, cleanliness and operative simplicity of the capillary extraction approach are remarkable, pros and cons are complementary to those of solid phase microextraction (SPME) or stir bar sorptive extraction (SBSE). Capillary extraction-capillary GC analysis of aqueous BTEX samples, in a clean water matrix, allows low part-per-billion detection limits, and does not require heated injectors or cryofocusing devices.

Benzene↗

PubMed2004

Comparison of different extraction methods for the analysis of volatile secondary metabolites of Lippia alba (Mill.) N.E. Brown, grown in Colombia, and evaluation of its in vitro antioxidant activity.

Hydrodistillation (HD), simultaneous distillation solvent extraction (SDE), microwave-assisted hydrodistillation (MWHD), and supercritical fluid (CO2) extraction (SFE) were employed to isolate volatile secondary metabolites from fresh leaves and stems of Colombian Lippia alba (Mill.) N.E. Brown. Kovàts indices, mass spectra or standard compounds were used to identify around 40 components in the various volatile fractions. Carvone (40-57%) was the most abundant component, followed by limonene (24-37%), bicyclosesquiphellandrene (5-22%), piperitenone (1-2%), piperitone (ca. 1.0%), and beta-bourbonene (0.6-1.5%), in the HD, SDE, MWHD, and SFE volatile fractions. Static headspace (S-HS), simultaneous purge and trap in solvent (CH2Cl2) (P&T), and headspace solid-phase microextraction (HS-SPME) were used to sample volatiles from fresh L. alba stems and leaves. The main components isolated from the headspace of the fresh plant material were limonene (27-77%), carvone (14-30%), piperitone (0.3-0.5%), piperitenone (ca. 0.4%), and beta-bourbonene (0.5-6.5%). The in vitro antioxidant activity of L. alba essential oil, obtained by hydrodistillation was evaluated by determination of hexanal, the main carbonyl compound released by linoleic acid subjected to peroxidation (1 mm Fe2+, 37 degrees C, 12 h), and by quantification of this acid as its methyl ester. Under the same conditions, L. alba HD-essential oil and Vitamin E exhibited similar antioxidant effects.

Antioxidants↗

PubMed2004

Analysis of volatile secondary metabolites from Colombian Xylopia aromatica (Lamarck) by different extraction and headspace methods and gas chromatography.

Hydrodistillation (HD), simultaneous distillation-solvent extraction (SDE), microwave-assisted hydrodistillation (MWHD), and supercritical fluid (CO2) extraction (SFE), were employed to isolate volatile secondary metabolites from Colombian Xylopia aromatica (Lamarck) fruits. Static headspace (S-HS), simultaneous purge and trap (P&T) in solvent (CH2Cl2), and headspace (HS) solid-phase microextraction (SPME) were utilised to obtain volatile fractions from fruits of X. aromatica trees, which grow wild in Central and South America, and are abundant in Colombia. Kováts indices, mass spectra or standard compounds, were used to identify more than 50 individual components in the various volatile fractions. beta-Phellandrene was the main component found in the HD and MWHD essential oils, SDE and SFE extracts (61, 65, 57, and ca. 40%, respectively), followed by beta-myrcene (9.1, 9.3, 8.2 and 5.1%), and alpha-pinene (8.1, 7.3, 8.1 and 5.9%). The main components present in the volatile fractions of the X. aromatica fruits, isolated by S-HS, P&T and HS-SPME were beta-phellandrene (53.8, 35.7 and 39%), beta-myrcene (13.3, 12.3 and 10.1%), p-mentha-1(7),8-diene (7.1, 10.6 and 10.4%), alpha-phellandrene (2.2, 5.0 and 6.4%), and p-cymene (2.2,4.7 and 4.4%), respectively.

Annonaceae↗

PubMed2004

Identification of volatile organic compounds emitted by a naturally aged book using solid-phase microextraction/gas chromatography/mass spectrometry.

Solid-phase microextraction (SPME) coupled to gas chromatography/mass spectrometry (GC/MS) has been applied to the analysis of volatile organic compounds emitted from a naturally aged groundwood pulp paper originating from an old book in order to access the products produced through the decomposition reactions occurring in paper upon ageing. Two different extraction methods were developed and compared: headspace SPME and contact SPME. The influence of few extraction parameters were tested in order to define the best extraction conditions. An optimised non-destructive contact SPME method was elaborated and allowed the characterisation of more than 50 individual constituents.

Books↗

PubMed2004

Automated high-capacity sorption probe for extraction of organic compounds in aqueous samples followed by gas chromatographic analysis.

An automated high-capacity sorption device for GC analysis of ultra trace components has been developed. The scope of the presented technique was to combine the simplicity of solid-phase microextraction (SPME) with the high extraction efficiency of the stir bar sorptive extraction technology. Sorptive extractions of water samples were performed using polydimethylsiloxane (PDMS) rubber tubing (120 microl) mounted onto a glass rod. The sampling procedure was carried out by a robotic autoinjector. Since the setup is fully automated, unattended and precise time-controlled extraction of samples is possible and makes quantitation with non-equilibrium extractions feasible. The sorption probes are easy to exchange, which facilitates off-line/in-field sampling. The system was evaluated with a test mixture of 44 environmentally hazardous compounds. Detection limits were found to be in the sub-ppt region. The performance of the system was demonstrated with the analysis of polycyclic aromatic hydrocarbons in urban snow.

Calibration↗

PubMed2004

Identification of 2,3-butanedione (diacetyl) as the compound causing odor events at trace levels in the Llobregat River and Barcelona's treated water (Spain).

A study of organic compounds imparting sweet and buttery odor problems in the Llobregat River (northeast Spain) and in treated water was conducted. Solid-phase microextraction (SPME), gas chromatography-olfactometry, and flavor profile analysis (FPA) were used as analytical methodologies to identify the compound responsible for odor incidents. 2,3-Butanedione (diacetyl) with a concentration range of 0.90-26 microg/l in river water samples entering the water treatment plant was identified as the compound causing the odor events. Flavor profile analysis establishes 0.05 microg/l as its odor threshold concentration (OTC) in water, with an odor recognition concentration of 0.20 microg/l. The analyses were carried out with SPME-GC-MS and parameters affecting SPME extraction such as selection of the fiber (carboxen-polydimethylsiloxane), extraction time (30 min), temperature (60 degrees C), and ionic strength were evaluated. Quality parameters of the optimized method gives good linearity (r2 > 0.999), a limit of detection (0.08 microg/l) similar to the OTC of the compound, and good reproducibility (R.S.D. < 20%). The SPME method was applied to identify the compound causing the odor.

Diacetyl↗

PubMed2004

Development of a novel solid-phase extraction element for thermal desorption gas chromatography analysis.

A novel solid-phase extraction element is developed for sorptive enrichment of dilute analytes from liquid samples with high extraction efficiencies due to its larger amounts of polydimethylsiloxane (PDMS) absorbent than the conventional syringe type of solid-phase microextraction (SPME). The extraction element is made of titanium (Ti) open tubular tube (30 mm x 1.2 mm i.d. x 1.6 mm o.d.) coated with a chemically bonded layer of PDMS (500 microm in thickness). The extraction element combined with thermal desorption-gas chromatography-mass spectrometry using a pyrolysis-gas chromatography-mass spectrometry system was used to extract and analyze a typical herbicide, bethrodine in water samples over a concentration range from 2.5 to 2.5 x 10(4) ng/l. Thus obtained calibration curve showed good linearity for the tested whole concentration range with regression coefficient of 0.992. Detection limit of 0.5 ng/l level was achieved and the reproducibility of the measurements for bethrodine at 10 ng/l level was found to be fairly good with relative standard deviation below 7.5%.

Calibration↗

PubMed2004

Identification of sulfur interferences during organotin determination in harbour sediment samples by sodium tetraethyl borate ethylation and gas chromatography-pulsed flame photometric detection.

Because of the high toxicity of organotin compounds and the current regulation about their applications, analytical method usable in routine analysis is required. A speciation procedure based on NaBEt4 ethylation and GC-PFPD analysis has shown to be suitable for the organotin determination. Unfortunately, some matrix effects were observed during the analysis of harbour sediments from Chile. These effects were identified as the alkylation of elemental sulfur and the coelution between the organotin compounds and some dialkylsulfides. The re-optimization of GC parameters and application of solid phase microextraction (SPME) were proposed to solve these analytical problems. Certified reference materials and different harbour sediment samples were analysed in order to evaluate the suitability of the methods for organotin control in complex environment samples.

Borates↗

PubMed2004

Determination of hexanal as indicator of the lipidic oxidation state in potato crisps using gas chromatography and high-performance liquid chromatography.

Hexanal (an oxidative state indicator) formed in the headspace of potato crisps during storage was evaluated using two different procedures. First, solid-phase microextraction, an innovative sampling preparation methodology was used. It consisted on the absorption of analytes directly from samples and subsequent thermal desorption on the gas chromatograph (GC) injector. Then, a reversed-phase high-performance liquid chromatographic technique (HPLC) was employed to quantify hexanal in the form of 2,4-dinitrophenylhydrazone derivative. Methods were evaluated in what concerns to validation parameters such as linearity, repeatibility and detection limit. GC (LOD = 1 ng/ml) method resulted in more sensitive method than HPLC (LOD = 9 ng/ml). The most suitable technique for hexanal measurement was selected.

Aldehydes↗

PubMed2005

Towards smaller and faster gas chromatography-mass spectrometry systems for field chemical detection.

Gas chromatography-mass spectrometry (GC-MS) is already an important laboratory method, but new sampling techniques and column heating approaches will expand and improve its usefulness for detection and identification of unknown chemicals in field settings. In order to demonstrate commercially-available technical advances for both sampling and column heating, we used solid phase microextraction (SPME) sampling of both water and air systems, followed by immediate analysis with a resistively heated analytical column and mass spectrometric detection. High-concern compounds ranging from 140 to 466 amu were analyzed to show the applicability of these techniques to emergency situations impacting public health. A field portable (about 35 kg) GC-MS system was used for analysis of water samples with a resistively heated analytical column externally mounted as a retrofit using the air bath oven of the original instrument design to heat transfer lines. The system used to analyze air samples included a laboratory mass spectrometer with a dedicated resistive column heating arrangement (no legacy air bath column oven). The combined sampling and analysis time was less than 10 min for both air and water sample types. By combining dedicated resistive column heating with smaller mass spectrometry systems designed specificallyfor use in the field, substantially smaller high performance field-portable instrumentation will be possible.

Gas Chromatography-Mass Spectrometry↗

PubMed2005

Experimental determination and calculation of distribution coefficients between air and fiber with polydimethylsiloxane coating for some groups of organic compounds.

This paper reports the results of experimental determination of distribution coefficients K(fa) for five terpene hydrocarbons and five aliphatic ketones between air and polydimethylsiloxane (PDMS) coating for solid-phase microextraction. To estimate the values of K(fa) for compounds of the same classes, which did not undergo experiments, it is proposed to use an empirical two-parameter equation in which various physicochemical and structural characteristics weakly correlated with each other are used as descriptors. It is also shown that for these purposes it is possible to use distribution coefficients of compounds in any other two-phase heterogeneous system, e.g. octanol-water or hexane-acetonitrile. This approach was applied to estimate K(fa) values of 92 volatile organic compounds.

Air↗

PubMed2005

Improved determination of flavour compounds in butter by solid-phase (micro)extraction and comprehensive two-dimensional gas chromatography.

The practicability and potential of comprehensive two-dimensional gas chromatography (GC x GC) coupled to both conventional flame ionisation (FID) and time-of-flight mass spectrometric (TOF-MS) detection, were compared with those of conventional one-dimensional (1D) GC, with the determination of flavour compounds in butter as an application. For polar flavour compounds, which were collected from the aqueous fraction of butter by means of solid-phase extraction (SPE), it was found that GC x GC dramatically improves the overall separation. Consequently, quantification and preliminary identification based on the use of ordered structures, can be performed more reliably. The improvement effected by replacing 1D-GC by GC x GC is considerable also in the case of TOF-MS detection, as illustrated by the high match factors generally obtained during identification. GC x GC was also used successfully for the characterisation of volatile flavour compounds in the headspace of butter collected by solid-phase microextraction (SPME) and to study the effect of heat treatment on the composition of butter samples in more detail.

Butter↗

PubMed2005

Flow-through system for the generation of standard aqueous solution of polycyclic aromatic hydrocarbons.

Standard aqueous solution of organic pollutants is used for the development of analysis methods and novel water sampling devices. The use of solid-phase microextraction (SPME) and other novel technologies for research in water sampling and analysis requires systems for the reliable generation of standard aqueous solution. In this communication, a new flow-through system based on permeation is introduced for the generation of standard aqueous solution of polycyclic aromatic hydrocarbons (PAHs). The main difference between the new developed system and typical system is that the syringe pump was changed with a permeation generator. The generator-based permeation offers many advantages, including convenient, inexpensive, solvent-free, long lifetime and production of high concentrations of the target analytes. The observed change in the concentration of the six PAH compounds was less than 20% over 3 months.

Dialysis↗

PubMed2005

Study of the interactions between phenolic compounds and micellar media using micellar solid-phase microextraction/gas chromatography.

Solid-phase microextraction coupled to gas-chromatography with mass-spectrometry detection has been employed to establish the sensitivity indexes as well as to study the partition coefficients of phenols into ionic and nonionic micelles. The sensitivity indexes values can be used to estimate qualitatively the affinity between phenols and micelles. The studied phenols, some of them with high environmental interest, include chloro-, alkyl-, and methoxy-phenols. The results obtained in this work, using 85 microm polyacrylate fiber and anionic (sodium dodecyl sulphate), cationic (cetyltrimethylammonium bromide), and nonionic (Triton X-100 and polyoxyethylene-10-lauryl ether) surfactants, indicate that SPME is a viable method for estimating the micelle partition coefficients.

Chromatography, Gas↗