bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis of classes of compounds of environmental concern: III. Organochlorine pesticides
Authors: Lopez‐Avila Viorica , Benedicto Janet , Baldin Emi , Beckert Werner F.
Published: May 2005

Forty five organochlorine pesticides (currently listed in EPA Method 8081A) have been chromatographed on DB‐5/DB‐1701 and SPB‐5/SPB‐1701 column pairs which were in each case connected to an inlet splitter and separate electron capture detectors. Thirteen additional compounds were evaluated for their suitability as internal standards or surrogate compounds for incorporation into Method 8081A. Method reproducibility and linearity are discussed, and results are presented for extracts of six real samples spiked with fifteen organochlorine pesticides and analyzed using the dual‐column, dual‐detector arrangement.
Hydrocarbon contaminants of boiled shrimp and crab meat
Authors: Misharina T. A. , Golovnya Rimma V.
Published: May 2005

Capillary GC and GC‐MS have been used for the identification and quantitation of n‐alkanes, naphthalenes, and alkylben‐zenes among the volatile components of crab and shrimp meat.
A detection method for unified chromatography: Ion mobility monitoring
Authors: Hill Herbert H. , St Louis Robert H. , Morrissey Mark A. , Shumate Christopher B. , Siems William F. , McMinn Dennis G.
Published: May 2005

Ion mobility monitoring has been used for detection in gas, supercritical fluid, and liquid chromatography, illustrating its potential as a method of detection for unified chromatography. Applications presented include GC‐IMD of dioxins in fly ash, SFC‐IMD of vitamin E, and HPLC‐IMD of alkylamines.

Ion mobility spectra of several mixed supercritical fluid mobile phases are also presented. Use of methanol, acetonitrile, and dichloromethane as modifiers of supercritical carbon dioxide, and use of supercritical dichlorodifluoromethane and chlorodifluoromethane as mobile phases had little effect on the reactant ion pattern at the flow rates and concentrations used in this study. Only when acetone was used as a modifier of carbon dioxide did the positive reactant ions change significantly. No effect of modifiers or mobile phase was observed for the negative reactant ions.
Detection of rare earth elements by post‐column reaction with xylenol orange and cetylpyridinium bromide
Authors: Hrdlička Aleš , Havel Josef , Valiente Manuel
Published: May 2005

Rare earth elements have been separated by HPLC on octadecyl‐bonded silica gel, dynamically modified with ammonium dodecylsulfate, using aqueous solutions of α‐hydroxyisobutyric acid as mobile phase.

The requirements and characteristics of post‐column reaction with xylenol orange and cetylpyridinium bromide were investigated and optimized, and the reaction found to be highly sensitive and sufficiently rapid. The absorbance of the complex at 598 nm was not affected by the presence of α‐hydroxyisobutyric acid at concentrations of the latter up to 150 mmol/l; at higher concentrations of the acid, the absorbance decreased slightly.

For most of the rare earth elements the response was linear up to 0.2 mmol/l; the relative standard deviation of peak area was, typically, ∼1 %. The sensitivity of the method was usually better than 1 μg/ml.

The results obtained from the determination of lanthanum, cerium, praseodymium, and neodymium in samples of apatite and bastnesite were in a good agreement with those obtained by ICP‐AES.
A versatile approach to the reproducible synthesis of functionalized polysiloxane stationary phases
Authors: Frank Hartmut , Abe Iwao , Fabian Gerd
Published: May 2005

Exploitation of the full potential of selector‐modified polysiloxanes as chromatographic stationary phases is limited because conventional methods of silicone synthesis involve strong acids or strong nucleophiles such as water or bases; under these conditions many potentially useful selectors decompose. The general approach to polysiloxane synthesis presented herein gives access to functionalized polysiloxanes under mild conditions. The functional groups incorporated can serve as chromatographic selectors or as electrophilic sites for secondary modification or cross‐linking.
Analysis of nitriles at low parts per million levels by capillary gas chromatography
Authors: Ehrmann Ursula , Carbognani Lante , Ceccarelli Claudio
Published: May 2005

Two methods have been developed for the determination of trace levels of acetonitrile and propionitrile in light naphthas. One involves clean‐up and preconcentration by medium pressure liquid chromatography (MPLC) in which nitriles are concentrated ten‐fold while the complex hydrocarbon matris is removed. The concentrated solution is then analyzed by high resolution GC with flame ionization detection. The second method involves direct injection of samples into a capillary GC equipped with chemiluminescence nitrogen detection.

The results and repeatability obtained from both methods are comparable. Preconcentration enables identification by GC‐MS and simultaneous analysis of other polar species, with no need for selective detectors. Direct analysis is, on the other hand, much less time‐consuming and requires less sample.
Combined Cl and El mass spectra in the analysis of essential oils
Authors: Zupanc Mira , Prošek Mirko , Dušan Milivojevič
Published: May 2005

As part of a study directed at introducing GMP recommendations to the production of non‐alcoholic beverages, combined Cl and El mass spectra have been used for the identification of compounds present in extracts of “Cockta” beverage following GC‐MS analysis. The amount of useful information present both in the separate Cl and El spectra, and in two of the possible combinations of the spectra, is described.
Cyclodextrin derivatives in the GC separation of racemic mixtures of volatile compounds, part V: Heptakis 2,6‐dimethyl‐3‐pentyl‐β‐cyclodextrins
Authors: Bicchi Carlo , Artuffo Giuseppe , D'Amato Angela , Manzin Valeria , Galli Anna , Galli Mario
Published: May 2005

This paper describes an evaluation of the chromatographic performance of columns coated with amorphous cyclodextrin (CD) derivatives, in particular 2,3,6‐tripentyl‐β‐CD (2,3,6‐TriPe‐β‐CD), 2,6‐dipentyl‐3‐methyl‐β‐CD (2,6‐DiPe‐3‐Me‐β‐CD), and 2,6‐dimethyl‐3‐pentyl‐β‐CD (2,6‐DiMe‐3‐Pe‐β‐CD), all diluted in polysiloxane (OV‐1701 or OV‐1701‐OH), for the separation of the enantiomers of volatile compounds. 2,6‐DiMe‐3‐Pe‐β‐CD in OV‐1701 offers performance comparable with (or better than) that of the other two CDs, and without their drawbacks (inconsistency of results, as described previously).

This article compares the separating ability of 2,6‐DiMe‐3‐Pe‐β‐CD and 2,3,6‐TriMe‐β‐CD, and describes the influence of the CD derivative to polysiloxane ratio, the minimum operating temperatures of the columns, and the reproducibility and consistency of performance of columns coated with the former CD derivative diluted in polysiloxane.
Investigation into the GC separation of enantiomers on a trifluoroacetylated cyclodextrin. I. Effect of analyte structure on stereoselectivity for alcohols
Authors: Smith Lan D. , Simpson Colin F.
Published: May 2005

More than 30 enantiomeric alcohols have been analyzed, without prior derivatization, by gas chromatography using a fused silica capillary column coated with octakis(3‐O‐trifluoro‐acetyl‐2,6‐di‐O‐n‐pentyl)‐γ‐cyclodextrin. Most were analyzed over a range of isothermal temperatures from 35 to 70°C. Enantiomeric separations were observed for most of the analytes, even at temperatures as low as 35°C.

The stereoselectivity of the stationary phase was found to depend on the length of the longest carbon chain attached to the stereogenic centre in 2‐ and 3‐hydroxy alkanes, the relative positions of the methyl and hydroxyl substituents in methylsubstituted alcohols, and the effects of multiple bonds in the analyte molecule. Thermodynamic data calculated from the results suggest that the enantiomers of all the analytes are resolved by a similar process. Retention and thermodynamic data are presented and possible mechanisms discussed.
The effect of dietary fish oil supplementation on the concentration of 3‐carboxy‐4‐methyl‐5‐propyl‐2‐furanpropionic acid in human blood and urine
Authors: Wahl Hans Günther , Tetschner Birgid , Liebich Hartmut M.
Published: May 2005

3‐Carboxy‐4‐methyl‐5‐propyl‐2‐furanpropionic acid (furanpropionic acid), a metabolite commonly found in human blood and urine, is one of the major acidic components which accumulates in the blood of patients with renal failure. Polyunsaturated fatty acids such as eicosapentaenoic acid (C20:5 ω−3) and long chain furan fatty acids, both present in commonly available fish oil capsules, are regarded as possible precursors of furanpropionic acid. Because of its strong binding to albumin and its various interactions with other endogenous and exogenous components, it is of great importance to determine the concentration of furanpropionic acid in blood and urine regularly.

Solid phase extraction has been used to concentrate furanpropionic acid from both blood and urine samples. After esterification with ethereal diazomethane, gas chromatographic separation was performed on a HP‐1 column (dimethylpolysiloxane). Quantitation with an internal standard was performed by mass selective detection in SIM‐mode, qualifier ions being used for identification and accuracy.

Fish oil supplementation of the diet of 24 patients for four weeks led to 3‐fold and 5 to 6‐fold increases in the levels of furanpropionic acid in serum and urine, respectively.
High performance liquid chromatographic–mass spectrometric detection of giant fullerenes
Authors: Anacleto Joseph F. , Boyd Robert K. , Quilliam Michael A.
Published: May 2005

Fullerene‐rich soot generated by resistive heating of graphite has been gently extracted with toluene, in order to remove some C60 and C70 compounds, followed by extraction with boiling 1,2,4‐trichlorobenzene at 214°C. After filtration and removal of the solvent, the residue was re‐dissolved in dichloromethane and characterized by non‐aqueous reversed phase liquid chromatography coupled on‐line with atmospheric pressure chemical ionization mass spectrometry. Several novel fullerenes were detected, including C72, C80, C86, and C88 as well as other fullerenes up to C108 and higher. The results indicate that chromatographic separation of large fullerene molecules can be achieved with low boiling point solvents and conventional liquid chromatographic techniques.
Carbon layer open tubular capillary columns
Authors: Sidisky Leonard M. , Robillard Mark V.
Published: May 2005

Capillary columns coated with Carbopack materials, which provide separation by a mixed partition/adsorption mechanism or by adsorption alone, have recently been developed. The reproducibility of the columns is demonstrated and applications shown in which they provide separations which are either unique or are faster than can be achieved with the wall coated open tubular capillary columns currently available.
On‐line single column capillary gas chromatographic analysis of all reactants and products in the synthesis of fuel methanol from hydrogen and oxides of carbon
Authors: Marsman Jan Henk , Breman Berthold B. , Beenackers Antonie A. C. M.
Published: May 2005

The main problems with complete analysis of the components of fuel methanol, or in Fischer‐Tropsch studies, are the several classes of compound present in the sample (permanent gases, water, alcohols, hydrocarbons), its wide range of components, its boiling point range, and the wide range of component concentrations.

A flexible on‐line GC method has been developed for kinetic study of catalyzed chemical reactions of hydrogen and oxides of carbon. The single capillary column, temperature programmed method was designed for complete analysis of reactants and products (hydrogen, carbon monoxide, carbon dioxide, water, C1‐C10 hydrocarbons, and C1‐C6 alcohols): a sample selection valve is used to switch between either the heated line used for input of the synthesis gases or the heated line used to transport reaction products from the reactor.

Sample is introduced to the capillary column by means of a 10‐port heated gas sampling valve with two external injection loops (0.07 and 1.95 cm3); this results in the determination of components over a wide range of concentrations in the sample (ppm to percentage levels). Helium from a pressure‐controlled supply is used as carrier gas and detection of the components is performed by serial connection of thermal conductivity and flame ionization detectors. Peak identification is performed by mass spectrometry and by comparison of component retention times.

The automated analytical equipment is integrated with a process control computer and delivers repeatable analytical results for the individual components (RSDs varying between 0.3 and 10% depending strongly on the concentration of the component and the accuracy of the determination of its peak area).
On‐line SFE‐GC for determination of PCBs in human milk and blood serum
Authors: Johansen Hege Rebecka , Thorstensen Christian , Greibrokk Tyge , Becher Georg
Published: May 2005

On‐line coupled supercritical fluid extraction and gas chromatography (SFE‐GC) has been utilized for the determination of PCBs and other organochlorine compounds in human milk and blood serum. The procedure involved preconcentration of the sample on C18‐silica sorbent in an extraction cell: after precipitation of the proteins up to 20 ml of human milk was concentrated on 0.5 g of sorbent. Serum (up to 5 ml) was applied to the C18 material without pretreatment. Basic alumina was utilized as a selective adsorbent for lipids in the on‐line SFE‐GC system. The method was used to analyze milk and serum spiked with 0.5 and 10 ng of Aroclor 1260 and the results compared with those obtained by liquid–liquid extraction of serum.
Fast identification of mycobacterium species by GC analysis with trimethylsulfonium hydroxide (TMSH) for transesterification
Authors: Müller Karl‐Dieter , Nalik H. Peter , Schmid Ernst N. , Husmann Heribert , Schomburg Gerhard
Published: May 2005

Trimethylsulfonium hydroxide (TMSH) reproducibly converts fatty acids bound in, e.g., biomolecules such as phospholipids and/or glycerides, into the corresponding fatty acid methyl esters (FAMEs). The transesterification can be performed at room temperature in a fast single step reaction. Surprisingly, secondary alcohols and mycolic acid cleavage products (MACPs) are also released from mycobacteria under these conditions.

The complex reaction mixtures containing FAMEs, MACPs, and secondary alcohols can easily be separated by high resolution temperature‐programmed capillary GC. Different species of mycobacteria give rise to characteristic chromatographic patterns and the amount of lipids from a single colony of mycobacteria is sufficient for reliable identification of the bacteria. The profiles of the chromatograms match well those obtained from other sample preparation techniques.

The TMSH method of identification of mycobacteria from the patterns of the gas chromatograms is faster and more sensitive than conventional methods, which also involve transesterification. The identification of mycobacterial species by microbiological culture techniques is difficult to perform and requires several weeks.
Selectivity and efficiency enhancement of supercritical fluid extraction by application of reactive additives. I. The analysis of calcium montanate using citric acid as a complexing agent
Authors: Venema Arnold , Jelink Theo J.
Published: May 2005

It has been demonstrated that calcium montanate (a mixture of aliphatic hydrocarbons, fatty acid esters of C28–C32 acids, the calcium salts of these fatty acids, and the acids themselves) can be selectively extracted with supercritical fluids. By use of carbon dioxide, carbon dioxide containing 10% methanol, and carbon dioxide containing 10% methanol and citric acid (as a further additive), the various compound classes could be isolated with high selectivity. The addition of citric acid results in the complexation of Ca2+ and the simultaneous formation of the free fatty acids, which are soluble in the extractant.
Potential and limitations of differently designed programmed‐temperature injector liners for large volume sample introduction in capillary GC
Authors: Staniewski Jacek , Rijks Jacques A.
Published: May 2005

Programmed temperature sample introduction is an attractive technique both for the introduction of large volumes of dilute samples in capillary gas chromatography and for LC‐GC interfacing.

In this study a new type of liner containing a porous bed of sintered glass is introduced and evaluated. Solute recoveries achieved with this liner are compared with those obtained from liners packed with Tenax TA and Thermotrap TA. An open liner containing baffles and a small plug of silanized glass wool in its upper section was used as a reference.

The maximum speed of sample introduction allowable using the new liner is ca one order of magnitude higher than for the standard liner. For similar liner operating conditions the trapping efficiency is substantially improved: at a liner temperature of −30°C components with a volatility lower than or equal to that of n‐tridecane are trapped quantitatively.

Liners packed with trapping materials such as Tenax TA or Thermotrap TA also provide significantly improved trapping efficiencies, even when used at relatively high temperatures.
Extending the scope of enantiomer separation by capillary supercritical fluid chromatography on immobilized polysiloxane‐anchored permethyl‐β‐cyclodextrin (Chirasil‐Dex)
Authors: Jung Martin , Schurig Volker
Published: May 2005

Immobilized polysiloxane‐anchored permethyl‐β‐cyclodextrin (Chirasil‐Dex) with a cyclodextrin content of approximately 30 % by weight, previously employed as a versatile chiral stationary phase for the separation of enantiomers by GC, has been used for the separation of enantiomers by capillary supercritical fluid chromatography (SFC). A considerable number of racemates could be resolved, e.g. aromatic alcohols, amino alcohols (TFA derivatives), and underivatized acids. Many pharmaceutical compounds were among those analyzed, including several NSAIDs (e.g. ibuprofen and ketoprofen), a steroidal drug (nor‐gestrel), a barbiturate (hexobarbital), and others.

Among the racemates resolved were many which cannot be analyzed by GC owing to low volatility or decomposition at elevated temperatures. For two racemates, analysis temperature and mobile phase density were systematically varied to give constant analysis times or capacity factors k. Low temperatures (ca 60 °C) yielded the best separation in term of separation factor, α, or resolution, Rs, even though higher densities had to be used. In comparison with GC, capillary SFC was able to furnish higher separation factors and similar resolution. The applicability of capillary SFC for the analysis of mixtures of cyclodextrin derivatives, e.g. those used in the synthesis of Chirasil‐Dex, was, furthermore, demonstrated.
Evaluation of flow restrictors for open‐tubular supercritical fluid chromatography at pressures up to 560 atm
Authors: Pinkston J. David , Hentschel Rosemary T.
Published: May 2005

Proper performance of the flow restrictor is of crucial importance in supercritical fluid chromatography. This is especially the case when the restrictor is the interface between the chromatographic column and a detector operating at lower pressure than the column. The performance of three types of fixed flow restrictor, the “tapered”, the “integral”, and the “frit”, was examined. The test mixtures chosen covered a range of polarities and molecular weights. Polydimethylsiloxane with an average molecular weight of 10,000 was used as a low polarity probe. Two polyethylene glycol mixtures were chosen as higher polarity probes. One consisted of a mixture of polyethylene glycol standards with average molecular weights ranging from 200 to 1450. The other polyethylene glycol mixture had an average molecular weight of 2000. The polydimethylsiloxane standard did not elute when the frit restrictor was used. Satisfactory results were obtained when the tapered and integral restrictors were employed. All three restrictors provided satisfactory results for polyethylene glycol oligomers eluting up to approximately 40.5 MPa (400 atm). However, for oligomers eluting above this pressure, the peaks merged into a broad hump with the frit restrictor, while the tapered and integral restrictors provided satisfactory separations. The integral restrictor produced more evenly spaced, more well resolved peaks at the high‐pressure end of the chromatograms than did the tapered restrictor. This is shown to be due to differences in the rates of increase in mobile‐phase velocity with increasing pressure for the two restrictors.
Indirect conductimetric detection of cyclodextrins in liquid chromatography
Authors: Takeuchi Toyohide , Miwa Tomoo , Hemmi Akihide , Maeda Tsuneaki
Published: May 2005

Indirect conductimetric detection of cyclodextrins (CDs) was investigated in liquid chromatography (LC). The mobile phase contained an electrolytic substance which maintained high background, and CDs were indirectly detected owing to a depression of the background signal due to dilution of the mobile phase by the analyte molecules. The dynamic reserve, defined as the ratio of the background to its noise level, was (1–2) × 105, and the detection limits at S/N = 3 were 23–40 ng for CDs when a microcolumn LC system was employed.
HRGC and GC–MS analysis of essential oil from colombian ylang‐ylang (Cananga odorata Hook fil. et Thomson, forma genuina)
Authors: Stashenko Elena , Martinez Jairo René , MacKu Carlos , Shibamoto Takayuki
Published: May 2005

Samples of essential oil from Colombian ylang‐ylang trees were analyzed by means of HRGC, HRGC–MS, IR and 1H‐ and 13C‐NMR. 57 components were detected, 51 of which were positively identified. Camphene and anethol were identified in ylang‐ylang essential oil for the first time. Among the composition‐determining variables studied (extraction time, part of the flower, and flower freshness), the extraction time and the flower condition (fresh versus dry) were found to have the largest incidence in the quality of the essential oil.
On‐line liquid backflush—a new technique for GC analysis of samples containing nonvolatile material
Authors: Hagman Gunnar , Roeraade Johan
Published: May 2005

Deteriorated performance in capillary GC is often caused by the deposition of nonvolatile components in capillary GC inlets. In many cases this is a limiting factor in trace analysis of complex samples. Volatile solutes of the sample interact with the high boiling material, which leads to broadened and unsymmetrical peaks. This paper describes a novel technique which utilizes independent temperature programs of a retention gap and the column as well as a liquid backflush of the retention gap. Samples that normally contaminate the retention gap after a few injections can be repeatedly injected over extended periods of time, while the chromatographic resolution is retained.
Procedure for testing inertness of inserts and insert packing materials for GC injectors
Authors: Grob Konrad , Wagner Christoph
Published: May 2005

The inertness of injector inserts and insert packing materials, such as glass or fused silica wool, is tested by a procedure based on split injection and rapid isothermal chromatography. Resulting sharp peaks sensitively reveal peak deformation resulting from adsorptivity, acid/base interaction, and excessive retention power. Degradation of labile components is detected by loss of material and degradation products. Adsorptivity was no problem on injecting 300 ng amounts. Degradation only occurred for raw wools; however, the retention power of some wools seemed unnecessarily high. On injection of smaller quantities, degradation remained similar, but adsorptivity increased significantly.
Construction of an all‐glass/fused silica, zero dead volume multidimensional gas chromatographic system using press‐fit connectors: Preliminary results
Authors: Ibáñez Carlos
Published: May 2005

A multidimensional gas chromatographic system has been constructed using commercially available press‐fit connectors, glass splitters, and fused silica lines. In this new design all the lines are continuously purged with carrier gas, ensuring no dead volumes in the chromatographic path. Some preliminary results and practical considerations are presented.
Analysis of volatiles associated with industrial scale processing of expanded polystyrene. Part I: Methods development
Authors: Hathcock Stanley L. , Bertsch Wolfgang
Published: May 2005

This paper reports on the methodology to collect volatiles from the hot‐wire cutting of expanded polystyrene. Analytical scale pyrolysis was used to model the conditions in the field. It appears that gas chromatographic profiles are little affected by the presence or absence of flame retardants. Pyrolysis in air or in an inert gas generates very similar pyrograms but the temperature at which pyrolysis takes place is the major factor affecting amount and distribution of volatiles. An experimental design is discussed that permits to model in the laboratory the production of volatiles generated in the field.
Capillary gas chromatography of the terpene components of Picea abies K.
Authors: Boscherini Giovanna , Michelozzi Marco
Published: May 2005

The terpene composition of cortical tissue in five Italian populations of Picea abies K. has been analyzed by headspace gas chromatography. The results of analysis of variance showed significant differences in content of most terpenes between the populations. Because intensive sampling is required for description of the natural variability of forest trees, the application of headspace gas chromatography may provide many opportunities in genetic research.
Electrochemical detection for trace analysis by capillary HPLC
Authors: Ruban Vladimir F.
Published: May 2005

An amperometric‐type electrochemical detector is proposed for use in capillary HPLC. Its cell (volume 60 nl) contains a cylindrical working electrode for detecting the presence of electroactive compounds. The noise level is 3–5 pA depending on the potential. The minimum detectable concentrations of the o‐, m‐, and p‐ isomers of nitrophenol (after separation of a 20 μl sample on a fused silica column) lies between 4 and 18 ng/l. The relative standard deviation of the height of the chromatographic peaks of phenols present at concentrations of 10 ppb does not exceed 0. 08 (n = 5).
Micellar electrokinetic capillary chromatography of nucleic acid constituents and dinucleoside monophosphate photoproducts
Authors: Ramsey Roswitha S. , Kerchner Geoff A. , Cadet Jean
Published: May 2005

Micellar electrokinetic capillary chromatography has been explored as an efficient and rapid method of separating the photoproducts of 2′‐deoxyuridylyl‐(3′‐5′)‐thymidine (i.e., cis‐syn and trans‐syn cyclobutane dimers, (6–4) photoproduct, and the related Dewar valence isomer) from normal nucleosides and nucleotides. Three cationic surfactants, dodecyl‐, tetradecyl‐, and hexadecyltrimethy‐lammonium bromide were evaluated and the separations compared with those obtainable with the anionic surfactant, sodium dodecylsulfate. Optimum resolution of the dinucleoside monophosphate photoproducts was obtained using tetradecyltrimethylammonium bromide. By use of this detergent the photoproducts could also be separated from other normal constituents in less than 6 min at −25 kV. Dodecyl‐ and hexadecyltrimethylammonium bromide provided some separation between the various species but sodium dodecylsulfate did not separate the UV radiation‐induced products from either the parent compound or other dinucleoside monophosphates. Increased interaction between negatively charged solutes and positively charged micelles accounts for the differences.
Chemical characterization of gorse pyrolytic oils by capillary gas chromatography
Authors: Bódalo Antonio , León Gerardo , Asanza María Luisa , Gómez Elisa , Guzmán María Amelia
Published: May 2005

Thermochemical conversion of biomass produces solid charcoal, gaseous fuels, and condensable oils. Because these oils vary widely in composition depending on the cellulosic feedstock and the operating conditions used, analysis of the oils is necessary in order to determine the best ways of utilizing or disposing of them. The major components of the organic oil from pyrolysis of gorse have been characterized by capillary gas chromatography – mass spectrometry. A qualitative study of the aqueous oil from the same source has also been attempted.
The performance of various capillary columns for the analysis of volatile flavor compounds in dairy products by dynamic headspace gas chromatography
Authors: Imhof René , Bosset Jacques O.
Published: May 2005

The aim of this study was to test the suitability and performance of various stationary phases and column dimensions for dynamic headspace gas chromatography of food aromas. The trials were performed using an aqueous test mixture containing thirty seven volatile flavor components of intense aroma, and a sample of ripe Swiss Emmental cheese.

The best performance with both samples was obtained with a capillary column coated with a thick film of polydimethylsiloxane. This column resolved the greatest number of compounds in the cheese sample and resulted in the overlapping of one pair of peaks only from the test mixture. Because of its other advantages, i. e. high capacity owing to its film thickness, and insensitivity to the high moisture content of some samples or traces of oxygen in the carrier gas, the polydimethylsiloxane column appears suitable for the analysis of the volatile and highly polar compounds present in complex mixtures such as food aroma.
Separation of fuels, heavy fractions, and crude oils into compound classes: A review
Authors: Lundanes Elsa , Greibrokk Tyge
Published: May 2005

Practically all the conventional chromatographic techniques are used in the characterization of the highly complex mixtures of organic compounds occurring in fuels, heavy fractions, and crude oils. This paper surveys the techniques employed for class determination, preparative fractionation of the main classes, and determination of subgroups after class fractionation.
Adsorptive interaction between nitrogen compounds and organic and/or mineral phases in subsurface rocks. Models for compositional fractionation of pyrrolic nitrogen compounds in petroleum during petroleum migration
Authors: Li Maowen , Larter Steve R. , Frolov Yeuge B. , Bjoroy Malvin
Published: May 2005

The results are reported of a range of laboratory chromatographic fractionation experiments with synthetic model compounds and a petroleum pyrrolic nitrogen fraction. Reversed phase separation of pyrrolic nitrogen compounds was governed mainly by the number of carbon atoms in the molecule, with little selectivity toward different positional isomers, whereas normal phase separation of the compounds could be explained in terms of steric effects related to alkylation position. Comparison of experimental results from model compounds with observations made previously using sets of natural samples taken from sedimentary basins clearly suggests adsorptive interactions between organic and mineral phases are involved in the compositional fractionation of pyrrolic nitrogen compounds in petroleum during migration. Detailed studies of the effects of petroleum migration on the molecular distribution of petroleum pyrrolic nitrogen compounds may provide useful, quantifiable, migration‐related geochemical parameters.
Chromatographic characterization of thermally upgraded products from alternative fuels
Authors: Lanças Fernando M. , Vilegas Janete H. Y. , Martins Sérgio , Gobato Elaine A. F.
Published: May 2005

An overview is presented of the analytical approaches developed by our research group over the last ten years for analysis of alternative fuel, both biomass and fossil. The alternative fuels are analyzed successively by PLC‐8 (preparative liquid chromatography–group‐type) fractionation and high resolution gas chromatography. Some of the possibilities for fractionation and characterization of alternative fuels are herein exemplified with sugar cane bagasse pyrolysis products.
Analysis of Fischer‐Tropsch by‐product waters by gas chromatography
Authors: Anderson Richard R. , White Curt M.
Published: May 2005

This paper describes a quantitative technique for the determination of organic constituents in Fischer‐Tropsch by‐product waters. Temperature‐programmed gas chromatography on derivatized bonded polar capillary columns provides the required separation that permits reliable quantitation of individual compounds. A preliminary combined gas chromatographic–mass spectrometric survey to identify the components present in Fischer‐Tropsch by‐product waters is presented. The elution order of 58 identified components is tabulated. Components identified in a typical Fischer‐Tropsch by‐product water include C1–C9 linear and branched alcohols, C3C8 ketones, C2C6 carboxylic acids, and C2C4 linear aldehydes.
Supercritical fluid chromatography of petroleum products using flameless sulfur chemiluminescence detection
Authors: Shearer Randy L. , Skelton Ron J.
Published: May 2005

Supercritical fluid chromatography using flameless sulfur chemiluminescence detection has been investigated for the analysis of sulfur compounds in petroleum products. The chromatography and detection system was easy to implement and exhibited good precision, linearity, selectivity, and sensitivity. A minimum detectable limit of 0.3 pg sulfur/s was obtained, and response to sulfur in different sulfur species was nearly equimolar.
Nitrogen speciation of polar petroleum compounds by compound class separation and on‐line liquid chromatography – mass spectrometry (LC‐MS)
Authors: Hsu Chang Samuel , Qian Kuangnan , Robbins Winston K.
Published: May 2005

Chromatography on Attapulgus clay and on silicic acid has been used to isolate ‘neutral’ and ‘basic’ nitrogen fractions from the 650–1050 °F distillate of an off‐shore Californian crude oil. These polar compounds were subjected to on‐line liquid chromatography – mass spectrometric (LC‐MS) analysis using low voltage electron‐impact ionization high resolution mass spectrometry (LVEI HRMS) and deuterated ammonia chemical ionization (ND3 Cl) to determine the molecules' elemental composition and number of exchangeable hydrogen atoms. On‐line separation of heavy oils into saturated, 1–4 ring aromatic, and polar compounds was performed by normal phase high performance liquid chromatography (HPLC) on a dinitroanilinopropyl (DNAP) silica column.
Enantiomeric composition of the chiral constituents of essential oils. Part 2: Sesquiterpene hydrocarbons
Authors: König Wilfried A. , Rieck Angela , Hardt Ingo , Gehrcke Bärbel , Kubeczka Karl‐Heinz , Muhle Hermann
Published: May 2005

A number of sesquiterpene hydrocarbons commonly occurring in essential oils has been prepared as racemic mixtures by chemical synthesis. Preparative gas chromatography with selectively per‐O‐alkylated cyclodextrins has been employed for the isolation of enantiomeric mixtures or pure enantiomers from the essential oils of higher plants and liverworts (Hepaticae). The enantiomers of α‐curcumene, α‐ and β‐bisabolene, β‐elemene, δ‐elemene, α‐copaene, δ‐cadinene, cis‐ and trans‐calamenene, and bicyclogermacrene could be resolved by enantioselective gas chromatography on capillary columns coated with cyclodextrin derivatives. The enantiomeric composition of these sesquiterpene hydrocarbons in various essential oils was determined.
High temperature gas chromatography for the analysis of fossil fuels: A review
Authors: Philp R. Paul
Published: May 2005

For the past two or three decades geochemists have been concerned with the analyses and characterization of compounds, generally hydrocarbons, ranging from C1C40. Significant amounts of information have resulted from these studies which have been extremely useful in many geochemical and environmental studies. However, in the past two or three years the commercial development and availability of high temperature gas chromatography columns has lead to the investigation of the occurrence and distribution of high molecular weight hydrocarbons (HMWHC), and other compounds, in the carbon number range C40C100, present in oils, waxes, bitumens and rock extracts. The ability to study these compounds represents a major advance in organic geochemistry. In some samples these compounds may represent the bulk of the organic components but prior to development of the high temperature columns it was impossible to study their distributions.

This paper will review advances that have occurred in terms of the application of high temperature gas chromatography (HTGC) to the analyses of fossil fuel samples and discuss the possible origin and significance of these compounds that have been identified. In addition, some of the potential problems involved in the analyses of these compounds will also be discussed.
Determination of the boiling point distribution of sulfur compounds in light cycle oil using GC with a flame photometric detector and pyrolyzer
Authors: Sung N. J. , Johnson S. J. , Parrott S. L.
Published: May 2005

A method has been developed to determine the boiling point distribution of sulfur compounds in light cycle oils (LCO'S). The method chosen for this analysis was GC with a flame photometric detector (FPD) and pyrolyzer. Tests were carried out to evaluate the recovery efficiency, repeatability, and accuracy of the method. Repeatabilities within 2% were obtained. The recovery of benzothiophenes and dibenzothiophenes was close to 100%; this was important because these are the major sulfur components in LCO's. No hydrocarbon or solvent interferences were observed with the use of the pyrolyzer, even for a 95% solvent level. Comparison with results from other techniques showed that the method accurately determined the levels of sulfur compounds in the LCO boiling point range.
Liquid–solid disk extraction followed by supercritical fluid elution and gas chromatography of phenols from water
Authors: Tang Peter Hua‐Tang , Ho James S.
Published: May 2005

A method combining the techniques of liquid – solid disk extraction (LSDE) and supercritical fluid elution (SFE) has been developed for the phenols regulated by the Clean Water Act. LSDE uses a disk or membrane made of polytetrafluoroethylene (PTFE) fibrils impregnated with small particles, e.g. styrene divinylbenzene (SDB) resin, to extract phenols from water. After disk extraction the retained analytes are eluted from the disk using SFE. SFE is used as an alternative to liquid solvent elution with an organic solvent. Analytes are separated, identified, and quantified using gas chromatography – ion trap detector mass spectrometry (GC‐ITDMS). The method is capable of sub parts per billion detection limits, and precision of 5–28% RSD. Evaluation of various disks or membranes, such as C18‐silica disks, SDB disks, and ion exchange membranes, has also been performed for the extraction of phenols from water. The results obtained from the in‐situ aqueous acetylation of phenols and extraction of their acetates are quantitative. The utilization of LSDE and SFE techniques has proven to be a more effective approach than liquid – liquid extraction in minimizing air pollution and solvent waste.
Simultaneous enantioselective separation of chlordanes, a nonachlor compound, and o,p′–DDT in environmental samples using tandem capillary columns
Authors: Oehme Michael , Kallenborn Roland , Wiberg Karin , Rappe Christoffer
Published: May 2005

Two capillary columns, one coated with 90 % biscyanopropyl 10 % phenylcyanopropylpolysiloxane (RTx 2330) the other with dimethyl‐t‐butyl‐silylated β‐cyclodextrin dissolved in 85 % methyl 15 % phenyl polysiloxane (PS‐086), have, when employed in tandem, enabled the enantioselective separation of all the chiral chlordanes present in the fish oil reference material SRM 1588, without any overlap between enantiomers of different isomers. This capillary column combination is, furthermore, able to separate the enantiomers of other chiral polychlorinated pesticides such as o,p′–DDT, oxy‐chlordane, a chiral nonachlor, and heptachlor exo‐epoxide. It can be used to determine the enantiomer ratio of these compounds present in the low pg/g range in extracts of marine biota and ambient air.
High temperature gas chromatography of trimethylsilyl derivatives of alcohol ethoxylates and ethoxysulfates
Authors: Rasmussen Henrik T. , Pinto Angela M. , DeMouth Mark W. , Touretzky Pamela , McPherson Bruce P.
Published: May 2005

Conversion of ethoxylated alcohols to trimethylsilyl derivatives and subsequent high temperature gas chromatography allowed for the determination of alkyl chain distribution, mole average degree of ethoxylation and weight percent distribution of several commercial mixtures. Repetitive derivatizations and analyses of a mixture with a vendor specified mole average degree of ethoxylation of 3.0 (Neodol 23‐3), yielded an experimental result of 2.93 ± 0.05 (n = 6). Mixtures with different alkyl chain distributions and higher degrees of ethoxylation provided similar accuracy. Extension of the method to the analysis of ethoxylated alcohol sulfate raw materials and ethoxylated alcohol sulfates in dishwashing liquids is discussed.
Applications of a GC autosampler modified for headspace sampling
Authors: Penton Zelda
Published: May 2005

A GC autosampler designed for liquid injection was modified for static headspace sampling. The modification was very simple and involved replacement of the standard 10‐μL syringe with a 100‐μL gas‐tight syringe. Liquid samples (0.2‐1.0 mL) were placed in 2‐mL vials, normally used for liquid sampling and an aliquot of the head‐space above the liquid was withdrawn and injected into the GC. All parts of the sampling system were at ambient temperature. The system was found to be useful for several applications. Among those discussed in this paper are determination of ethanol in the blood or urine of individuals suspected of driving while intoxicated, residual organic solvents in pharmaceuticals, and screening of effluent waters from industrial plants for acrylonitrile.
Rapid analysis of free medium‐chain fatty acids and related ethyl esters in beer using SPE and HRGC
Authors: Battistutta F. , Buiatti S. , Zenarola C. , Zironi R.
Published: May 2005

A modification of a procedure by Hage [1] is proposed for the gas chromatographic evaluation of the content of free medium‐chain fatty acids and related ethyl esters in beer. The method involves extraction of free fatty acids and ethyl esters by SPE using C18 bonded phase columns, derivatization of free fatty acids and related ethyl esters with diazomethane, and GC analysis using an SP‐2340 capillary column. The results obtained have shown the method to be rapid and highly reproducible. The technique has been compared with other methods used for determination of free fatty acids.
Determination of neutral chlorinated extractable organic compounds in water samples using large volume on‐column injection capillary gas chomatography–mass spectrometry
Authors: Tamilarasan Ramasamy , Morabito Paul L. , Lamparski Les , Hazelwood Paul , Butt Alison
Published: May 2005

An automated large volume on‐column injection technique (LOCI) for capillary gas chromatography – mass spectrometry, GC‐MS, with solvent divert and heated retention gap technology has been used to simplify the method for determining sixteen neutral chlorinated extractable compounds (NCEC) in industrial plant process water samples at a level of 10 ng/L. According to the simplified procedure, 30 mL of water sample is extracted with 5 mL hexane, and 100 μL of the extract analyzed by combining large volume on‐column injection with mass‐selective detection operated in the selected ion monitoring mode. This combination has enabled simplification of the sample preparation and analysis procedures and provided a fast, labor‐saving technique for analyzing water samples. Simplifications include significant reduction of sample and eluent volumes during extraction, and elimination of the Kuderna‐Danish evaporative concentration step. The latter simplification has not only resulted in significant time savings, both during the analysis and for subsequent glassware cleaning; analyte losses and the introduction of contaminants and artifacts which may occur during this step have also been eliminated.

System behavior, e.g. linearity of detector response, method detection limit, and reproducibility, were evaluated for all sixteen analytes using spiked water samples in the lower ng/L range. The response of the mass detector is linear in the range 5–20000 ppt for all sixteen NCEC investigated. Injection of 100 μL of sample using LOCI makes it possible to achieve an instrument detection limit in the ppt range. The calculated method detection limits are similar to those of the instrument precision and are lower than the required method detection limit of 10 ppt.

Extraction efficiency has been maximized by optimizing sample‐to‐solvent ratio and extraction time. The extraction efficiency seems to be independent of sample‐to‐solvent ratio in the range of 2. 5 to 6 and increasing the extraction time from 25 to 120 minutes resulted in no significant increase in efficiency. Extraction efficiency also seems to be independent of the concentration of analyte in the water samples. The simplified procedure presented here was automated by means of a laboratory robot and used to generate all the extraction data reported in this manuscript.
Effect of ammonia carrier gas on the response of the flame ionization detector
Authors: Abdel‐Rehim Mohamed , Zhang Lin , Hassan Moustapha
Published: May 2005

The effect of using ammonia as a carrier gas on the response of the flame ionization detector (FID) has been investigated. It was found that the FID response, calculated as the effective carbon number (ECN), increased for all the compounds studied when ammonia, rather than helium, was used. The change was 0–0. 9 carbon atom for hydrocarbons, one carbon atom for alcohols and diphenyl ether, and 0.4–1 carbon atom for phenols and ketones. The increase in ECN was larger for amines (0. 8–5 carbon atoms), but these numbers also reflected an improvement in chromatographic performance as a result of reduced adsorption on the column. The largest change in signal‐to‐noise ratio, a six‐fold increase, was obtained for octyl‐amine; ratios for hexyl methyl ketone, diisobutyl ketone, dihexyl‐amine, dibutylamine, and N‐methyloctylamine increased by a factor of 2–3 when ammonia was used as carrier gas. To determine the extent to which the effect on detector response was solely attributable to ammonia, a mixture of 5 % ammonia in nitrogen was used as detector make‐up gas with helium as carrier gas. Under these conditions the noise in the FID increased but for most of the compounds studied the signal‐to‐noise ratio also increased.
Analysis of organomercury compounds in sediments by capillary GC with atomic fluorescence detection
Authors: Alli Azaam , Jaffé Rudolf , Jones Ronald
Published: May 2005

Analysis of methyl‐ and ethylmercury (MM and EM) halides in biological and environmental samples is generally performed by gas chromatography with electron capture detection. Tedious sample work‐up protocols and poor chromatographic response (using packed columns) have, however, shown the need for the development of new methods in this field.

This paper reports a sensitive method, free from these deficiencies, for the determination of methyl‐ and ethylmercury. The organomercury compounds (MM and EM) are first released from the sample matrix, by the combined action of acidic potassium bromide and cupric ions, and then extracted into dichloromethane. The initial extracts are subjected to thiosulfate clean‐up and the organomercury species are isolated as their chloride derivatives by addition of cupric chloride, and subsequent extraction into a small volume of organic solvent. Capillary GC coupled with atomic fluorescence detection provided excellent separation efficiencies for methyl‐ and ethylmercury and proved to be a very selective and sensitive technique. The absolute detection limit for both MM and EM was found to be 0.2 pg.