Application of headspace GC/MS screening and general parameters for the analysis of polycyclic aromatic hydrocarbons in groundwater samples

Groundwater samples from a former gas plant site were investigated by headspace GC/MS and general parameters with regard to organic pollution. The contamination plume was distinguished from background with GC/MS headspace and dissolved organic carbon analyses. Headspace GC/MS analyses of these samples revealed the presence of several aromatic and heterocyclic compounds typical to coal tar leachates. Selected ion monitoring GC/MS was used to establish the relative contamination level of seven selected polycyclic aromatic hydrocarbons (PAH) from 9 sampling wells. Three wells showed a high contamination level and therefore, they could be attributed to the vicinity of contamination sources. Well samples downgradient from the pollution source showed decreasing contamination levels for all compounds except acenaphthene.     

High-temperature (GC)2/MS investigations

The analysis of low volatile compounds by (GC)²/MS using high-temperature stable glass-capillary columns and a commercially available GC/quadrupole MS instrument is described. It will be shown that no special modifications or procedures are required in analyzing organic compounds exceeding carbon numbers of 50. The application to industrially and naturally occuring high boiling mixtures will be discussed.     

红景天挥发油的GC／MS／DS和GC／IR／DS研究

红景天挥发油的ＧＣ／ＭＳ／ＤＳ和ＧＣ／ＩＲ／ＤＳ研究阎吉昌，张宏徐少敏卫永弟，阎雪（东北师范大学测试中心，长春，１３００２４）（吉林省石油化工研究院，白求恩医科大学）关键词红景天，色谱／质谱，色谱／红外，复杂有机混合物应用色谱／质谱／计算机（ＧＣ／Ｍ...     

Chromatographic properties of the ion-exclusion column IonPac ICE-AS6 and its application in environmental analysis, Part II: application in environmental analysis

Biological processes, geochemical reactions, anthropogenic emissions, and transformation reactions of xenobiotics are responsible for the widespread occurrence of aliphatic carboxylic acids in the environment. To study the performance of the ion-exclusion chromatography column IonPac ICE-AS6 in the analysis of environmental and environmental-technical samples, organic acids are investigated in composting seepage, silage effluents, aqueous extracts of sewage sludge, molasses hydrolysate, and alkaline cellulose hydrolysates. With respect to the diverse sample matrix and composition, different chromatographic conditions are applied. It is possible to determine various volatile fatty acids, dicarboxylic acids, (poly)hydroxy acids, and keto acids as main and trace components in samples with very high and low dissolved organic carbon content. Low baseline noise allows the determination of malic and succinic acid in the concentration range of approximately 1 microM/L in the presence of higher concentrations of fully ionized compounds. The applicability of the column in environmental analysis may be limited by the poor retardation of strong organic acids, insufficient separation of some relevant substance combinations (i.e., citric and isocitric acid), and very strong hydrophobic interactions with straight-chain monocarboxylic acids containing four or more carbon atoms.     

Rapid and Sensitive Analysis of Diclofenac in Human Plasma by GC/SIM/MS

ABSTRACT

An analytical method for the determination of diclofenac with tolfenamic acid as the internal standard was developed and validated in human plasma by capillary gas chromatography-mass spectrometry (GC/MS). After the addition of the internal standard, the compounds were extracted from plasma at acidic pH into diethylether, which was then evaporated to dryness. The compounds were derivatized with pentafluoropropionic anhydride (PFPA) and a mixture (1000:2:3, v/w/w) of N-methyl-N-trimethylsilyltrifluoroacetamide (MSTFA), ammonium iodide (NH₄I), and dithioerythritol (DTE). They were determined by GC/MS at m/z 349 (a molecular ion) for diclofenac and m/z 270 (a base ion) for tolfenamic acid. The recovery of this procedure was 97.8%, and the linearity for calibration was 0.9907 as the coefficient factor. The detection and quantitation limits were 0.1 and 0.5 ng/mL, respectively.     

GC/MS, HPLC and FAB mass spectrometric analysis of organic micropollutants in Barcelona's water supply

Water samples from Llobregat river entering two water work plants, Barcelona tap water and waste dumping samples taken along the river course were analyzed for trace organic contaminants by different procedures, liquid-liquid extraction, adsorption on granular activated carbon followed by GC/MS/DS. Ether insoluble organic fractions were analyzed and fractionated by HPLC with diode-array detection, followed by FAB and FAB-CID-MIKE characterisation. Results, after two years monitoring, proved that surfactants, plasticizers, ethyleneglycol derivatives, phosphates, hydrocarbons and other miscellaneous compounds can be considered as chronic pollutants of Llobregat river. Some of the identified compounds by GC/MS and FAB mass spectrometry have not been previously reported to occur in water.     

Quantifizierung organischer Substanzen in Aktivkohleextrakten mit Hilfe der Gas-Chromatographie/Massenspektrometrie

Summary Use of activated carbon plays a significant role in water technology and analytical chemistry. Therefore determination of substances adsorbed on activated carbon is of special interest. As an example, granulated activated carbon (GAC) from a water treatment plant was serially extracted with different organic solvents. Quantitative determination of some selected compounds in the combined extracts was done by gas chromatography/mass spectrometry. The method of internal standard addition and calibration by response factors was used. The determined compounds (all of substituted benzene type) were extracted from the GAC in the concentration range from 0.2 mg/100 g (m-dichlorobenzene) to 5 mg/100 g (nitrobenzene). Relative standard deviation for double determination of five independent samples from the GAC filter was less than ±20%Spike experiments were performed to determine recovery efficiences. As expected, substance specific differences appeared and the recoveries were between 36% (m-dichlorobenzene) and 80% (nitrobenzene). A significant limitation for quantitative determination results from lack of available substances for calibration.     

Fast screening for presence of muddy/earthy odorants in wine and in wine must using a hyphenated gas chromatography-differential ion mobility spectrometry (GC/DMS)

Rapid, hyphenated detection techniques involving a gas chromatograph (GC) coupled to a classical time-of-flight ion mobility (IMS) spectrometer, or more recently, to a micro-machined, miniature differential ion mobility spectrometer (DMS) are quite attractive for in-situ detection of many kinds of volatile organic compounds (VOCs) of concern and notably of natural contaminants appearing in the headspaces of selected foodstuff. This work aims at a rapid detection, identification and quantification of geosmin in the headspace of grape must and of wine. Samples of white and red wines have both been analyzed with a hyphenated GC/DMS and by Solid Phase Micro-Extraction (SPME) coupled to GC/MS taken as a reference. The detection of geosmin at concentrations below the human olfactory threshold of 50 ng/L has been demonstrated.     

Analysis of fragrance compounds in blood samples of mice by gas chromatography, mass spectrometry, GC/FTIR and GC/AES after inhalation of sandalwood oil.

After inhalation experiments with sandalwood oil and the pure fragrance compounds coumarin and alpha-terpineol, substances were detected and measured in the blood samples of test animals (mice) using gas chromatography/mass spectrometry (GC/MS) (MID) in connection with GC/FTIR (SWC), GC/AES (carbon and oxygen trace) and flame ionization detection/gas chromatography. Using tiglinic acid benzyl ester as the internal standard the following concentrations in serum could be found: alpha-santalol 6.1 ng/mL, beta-santalol 5.3 ng/mL and alpha-santalene 0.5 ng/mL. In separate inhalation experiments with coumarin and with alpha-terpineol the corresponding concentrations were 7.7 ng/mL and 6.9 ng/mL, respectively.     

Determination of organic pollutants in coking wastewater by dispersive liquid–liquid microextraction/GC/MS

A method based on dispersive liquid–liquid microextraction coupled with GC/MS was developed for quantitative analysis of the major organic pollutants listed in the United States Environmental Protection Agency method 8270 and the 15 European‐priority polycyclic aromatic hydrocarbons in coking wastewater. The major parameters such as extraction solvent, dispersive solvent, solution pH, and extraction time were systematically optimized. The optimum extraction conditions were found to be: 15 μL mixture of 2:1 v/v carbon tetrachloride and chlorobenzene as the extraction solvent, 0.75 mL ACN as the dispersive solvent, solution pH of 8, and extraction time of 2 min. For the major pollutants listed in the United States Environmental Protection Agency 8270, the linear ranges were 0.1 to 100 mg/L, the enrichment factors ranged from 452 to 685, and the relative recoveries ranged from 67.5 to 103.5% with RSDs of 4.0–9.1% (n = 5) at the concentrations of 10 mg/L under the optimum extraction conditions. For the 15 polycyclic aromatic hydrocarbons, the linear ranges were 0.1 to 100 μg/L, the enrichment factors ranged from 645 to 723, and the relative recoveries ranged from 94.5 to 107.6% with RSDs of 4.6–9.0% (n = 5) at the concentrations of 10 μg/L. The usefulness of the developed method was demonstrated by applying it in the analysis of real‐world coking wastewater samples.     

Polymerization of novel trifluorovinyl ethers: Insight into the mechanisms of termination and chain transfer

New trifluorovinyl ether polymers were synthesized with the view toward overcoming the high chemical and thermal stabilities commonly associated with fluoropolymers. Trifluorovinyl ether copolymers, with fluorinated pendant groups, have previously been prepared to overcome limitations in processibility. To further enhance solubility in common organic solvents and to improve processibility, we prepared three new trifluorovinyl ether monomers, having hydrocarbon ether pendant groups, for polymerization: 1-[2-(2-ethoxy ethoxy)ethoxy]-1,2,2-trifluoroethene (Et-TFVE), 1-[2-(2-t-butoxy ethoxy)ethoxy]-1,2,2-trifluoroethene (t-Bu-TFVE), and 1-(2-phenoxy ethoxy)-1,2,2-trifluoroethene (Ph-TFVE). Homopolymers of these three monomers were prepared by aqueous emulsion polymerization with the use of a redox initiator. Poly(Et-TFVE) and poly(Ph-TFVE) were prepared with a range of molar masses, the highest of which had weight average molar masses of 33,800 g mol⁻¹ and 59,000 g mol⁻¹, respectively. As a result of monomer reactivity and structure, the polymerization mechanism was complicated, resulting in β-scission termination/chain transfer for all three polymers and hydrogen abstraction chain transfer for poly(Et-TFVE) and poly(t-Bu-TFVE). To the best of our knowledge, this is the first example of hydrogen abstraction from the pendant group of the trifluorovinyl ether itself. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 3301–3308, 1999     

Methods for the determination of neutral drugs as well as betablockers and β2-sympathomimetics in aqueous matrices using GC/MS and LC/MS/MS

An analytical method has been developed which allows the determination of 22 different neutral and weakly basic drugs belonging to several different medicinal classes like antiphlogistics, betablockers, β₂-sympathomimetics, lipid regulators, antiepileptic agents, psychiatric drugs and vasodilators in waste water as well as in river and drinking water. A method including solid phase extraction, derivatization by silylation and detection by GC/MS permits detection down to 5 ng/L. The recovery rates mostly exceeded 70%. However, the determination of phenazone, carbamazepine, cyclophosphamide, ifosfamide and pentoxiphylline is frequently disturbed by organic co-extractants in real samples of rivers and waste waters. Therefore, a time saving alternative method has been developed, combining solid phase extraction (as an enrichment step) together with detection by LC-electrospray/MS/MS allowing the measurement of 5 neutral drugs. Detection limits down to 10 ng/L have been achieved even for organically highly contaminated waters like sewage treatment plant effluents. Received: 18 November 1997 / Revised: 18 March 1998 / Accepted: 21 March 1998     

Analysis of nitrosamines in water by automated SPE and isotope dilution GC/HRMS Occurrence in the different steps of a drinking water treatment plant, and in chlorinated samples from a reservoir and a sewage treatment plant effluent

A method based on automated solid-phase extraction (SPE) and isotope dilution gas chromatography/high resolution mass spectrometry (GC/HRMS) has been developed for the analysis of nine nitrosamines in water samples. The combination of automated SPE and GC/HRMS for the analysis of nitrosamines has not been reported previously. The method shows as advantages the selectivity and sensitivity of GC/HRMS analysis and the high efficiency of automated SPE with coconut charcoal EPA 521 cartridges. Low method detection limits (MDLs) were achieved, along with a greater facility of the procedure and less dependance on the operator with regard to the methods based on manual SPE. Quality requirements for isotope dilution-based methods were accomplished for most analysed nitrosamines, regarding to trueness (80–120%), method precision (<15%) and MDLs (0.08–1.7 ng/L).Nineteen water samples (16 samples from a drinking water treatment plant {DWTP}, 2 chlorinated samples from a sewage treatment plant {STP} effluent, and 1 chlorinated sample from a reservoir) were analysed. Concentrations of nitrosamines in the STP effluent were 309.4 and 730.2 ng/L, being higher when higher doses of chlorine were applied. N-Nitrosodimethylamine (NDMA) and N-nitrosodiethylamine (NDEA) were the main compounds identified in the STP effluent, and NDEA was detected above 200 ng/L, regulatory level for NDMA in effluents stated in Ontario (Canada). Lower concentrations of nitrosamines were found in the reservoir (20.3 ng/L) and in the DWTP samples (n.d. −28.6 ng/L). NDMA and NDEA were respectively found in the reservoir and in treated and highly chlorinated DWTP samples at concentrations above 10 ng/L (guide value established in different countries). The highest concentrations of nitrosamines were found after chlorination and ozonation processes (ozonated, treated and highly chlorinated water) in DWTP samples.     

Evolution of Brassica rapa var. rapa L. volatile composition by HS-SPME and GC/IT-MS

Brassica rapa var. rapa L. (turnip) is highly appreciated and consumed by human. In this work, the volatile profile of B. rapa var. rapa was studied during the maturation process. The volatiles of seeds, sprouts with 6 and 9 days, and adult plant were determined using headspace solid-phase microextraction (HS-SPME) combined with gas chromatography/ion trap-mass spectrometry (GC/IT-MS).Several constituents, including alcohols, aldehydes, esters, ketones, norisoprenoids, nitrogen and sulphur compounds were characterized, totalizing 64 compounds. Isothiocyanates are the main volatiles in all matrices, being 3-butenyl isothiocyanate the major compound. Qualitative and quantitative differences were found among the analysed materials. Nitrogen and sulphur compounds decreased during the maturation process, while terpenes, aldehydes, norisoprenoids and ester compounds were present in higher amounts during germination, especially in sprouts with 9 days of development.     

固相微萃取-气相色谱联用技术在环境分析中的应用

本文综述了近5年来固相微萃取-气相色谱(SPME-GC)联用技术在环境分析中的应用进展.具体介绍了它在多环芳烃、苯系物、酚类化合物、农药、杂环化合物以及其他有机挥发物分析中的应用.引用文献158篇.     

Influence of salinity and natural organic matter on the solid phase extraction of sterols and stanols: application to the determination of the human sterol fingerprint in aqueous matrices

Faecal sterols have been proposed as direct chemical markers for the determination of faecal contamination in inland and coastal waters. In this study, we assess the impact of (a) the concentration of dissolved organic carbon (DOC), (b) the nature of DOC, (c) the salinity and (d) the concentration of sterols and stanols on their solid phase extraction. When natural organic matter (NOM) is modelled by humic acid, increasing DOC concentration from 2.7 to 15.4 mg/L has no significant impact on the recovery of sterols and stanols. The modelling of NOM by a mixture of humic acid and succinoglycan induces a significant (24%) decrease in the recovery of sterols and stanols. For all concentrations of target compounds, no significant increase in recovery is associated with increasing the salinity. Moreover, an increase in the recovery of target compounds is induced by an increase in their concentration. The nine target compounds and the recovery standard (RS) exhibit the same behaviour during the extraction step. Thus, we propose that (a) the concentration of target compounds can be corrected by the RS to calculate more realistic concentrations without modifying their profile and (b) the sterol fingerprint can be investigated in the colloidal fraction of aqueous samples without altering the information it could provide about the source. The application of this analytical method to waste water treatment plant influent and effluents yields results in agreement with previous studies concerning the use of those compounds to differentiate between sources of faecal contamination. We conclude that this analytical method is fully applicable to the determination of sterol fingerprints in the dissolved phase (<0.7 μm) of natural aqueous samples.     

Tandem GC/MS: A useful tool for studying end-capping reactions of oligo(styryl)lithium anions

Anionic living polymerization methods, using organometallic initiators such as butyllithium reagents, have proven useful for, inter alia, styrene polymerization and are amenable to subsequent functionalization of poly(styryl)lithium in the termination step. In this study, general methods for the selective preparation of small styrene oligomers and termination of the intermediate oligo(styryl)lithium anions were investigated. The crude reaction mixtures were analyzed directly by tandem gas chromatography/mass spectrometry (GC/MS). Of the carbon- and silicon-based electrophiles tested, chloro(chloroalkyl)silanes, Cl-SiR₂(CH₂)_nCl in particular, were shown by GC/MS to be regioselective end-capping reagents, thus allowing subsequent transformation to the primary amine. The combined GC/MS data allow not only an estimate of the degree of functionalization, but also the identification of by-products, thus providing insight into the end-capping process that otherwise might be difficult to access. © 1995 John Wiley & Sons, Inc.     

A preconcentrator coupled to a GC/FTMS: Advantages of self-chemical ionization,mass measurement accuracy,and high mass resolving power for GC applications

Coupling of a cryogenic preconcentrator (PC) to a gas chromatograph/Fourier transform ion cyclotron resonance mass spectrometer (GC/FT-ICR MS) is reported. To demonstrate the analytical capabilities of the PC/GC/FT-ICR MS, headspace samples containing volatile organic compounds (VOCs) emitted from detached pine tree twigs were analyzed. Sub-ppm mass measurement accuracy (MMA) for highly resolved (m/Deltam(50%) > 150 k) terpene ions was achieved. Direct PC/GC/FT-ICR MS analyses revealed that detached twigs from pine trees emit acetone, camphor, and four detectable hydrocarbon isomers with C(10)H(16) empirical formula. The unknown analytes were identified based on accurate mass measurement and their mass spectral appearances. Authentic samples were used to confirm initially unknown identifications. Self-chemical-ionization (SCI) reactions furnished an additional dimension for rapid isomer differentiation of GC eluents in real time.     

Poly(L‐glutamic acid) grafted with oligo(2‐(2‐(2‐methoxyethoxy)ethoxy)ethyl methacrylate): Thermal phase transition,secondary structure,and self‐assembly

Thermoresponsive and pH‐responsive graft copolymers, poly(L ‐glutamate)‐g‐oligo(2‐(2‐(2‐methoxyethoxy)ethoxy)ethyl methacrylate) and poly(L ‐glutamic acid‐co‐(L ‐glutamate‐g‐oligo(2‐(2‐(2‐methoxyethoxy)ethoxy)ethyl methacrylate))), were synthesized by ring‐opening polymerization (ROP) of N‐carboxyanhydride (NCA) monomers and subsequent atom transfer radical polymerization of 2‐(2‐(2‐methoxyethoxy)ethoxy)ethyl methacrylate. The thermoresponsiveness of graft copolymers could be tuned by the molecular weight of oligo(2‐(2‐(2‐methoxyethoxy)ethoxy)ethyl methacrylate) (OMEO₃MA), composition of poly(L ‐glutamic acid) (PLGA) backbone and pH of the aqueous solution. The α‐helical contents of graft copolymers could be influenced by OMEO₃MA length and pH of the aqueous solution. In addition, the graft copolymers exhibited tunable self‐assembly behavior. The hydrodynamic radius (R_h) and critical micellization concentration values of micelles were relevant to the length of OMEO₃MA and the composition of biodegradable PLGA backbone. The R_h could also be adjusted by the temperature and pH values. Lastly, in vitro methyl thiazolyl tetrazolium (MTT) assay revealed that the graft copolymers were biocompatible to HeLa cells. Therefore, with good biocompatibility, well‐defined secondary structure, and mono‐, dual‐responsiveness, these graft copolymers are promising stimuli‐responsive materials for biomedical applications. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

锗钨酸盐的电化学性能及GeW11Co/P-oPD/GC电极对过氧化氢的电催化还原

研究了杂多酸-钴取代三聚Keggin结构锗钨酸盐（[Co（H2O）3（α-GeW11CoO38）3]10-）的电化学性能.实验表明,在玻碳（GC）电极上,锗钨酸盐循环伏安曲线呈现2对可逆的氧化还原峰,峰电位差分别为31 mV和35 mV,各对应于2电子4质子和2电子3质子电极反应,其过程受表面吸附控制.经过电聚合将Ge...