bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analysis of organic solvents in printing inks by headspace gas chromatography – mass spectrometry
Authors: Rastogi Suresh Chandra 
Published: May 2005

AbstractStatic headspace analysis by gas chromatography has been found to be a suitable method for the analysis of organic solvents in printing inks. Experimental conditions for the analysis have been optimized, and the accuracy and relative standard deviation of the method has been determined. The solvent content of 29 printing inks has been measured.
Analysis of seven chlorobiphenyl congeners by multidimensional gas chromatography
Authors: de Boer Jacob , Dao Quy T. 
Published: May 2005

AbstractChlorobiphenyl congeners (CBs) are used as indicator compounds in analysis performed to determine whether or not PCB concentrations in food products, waste mineral oil, and environmental samples comply with the maximum levels permitted by legislation. Seven of these compounds have been checked for coelution with other CB congeners by means of a multidimensional gas chromatographic method utilizing a combination of two narrow bore columns, one coated with a conventional non‐polar stationary phase and the other with a liquid crystalline (smectic) stationary phase.Peaks of the relevant CBs have been transferred, by heart cutting, from the non‐polar column to the liquid crystal column, on which unambiguous separation from possible coeluting CB congeners was obtained. It has been shown that if the seven congeners are analyzed solely on a single, non‐polar capillary column the results obtained for two of them may be affected by coelution of other compounds.
Analysis of pheromones: Enrichment on thick film capillary traps and GC detection with a living detector (EAD)
Authors: Burger Barend V. , Nell Anika E. , Petersen Warren G. B. 
Published: May 2005

AbstractInsect pheromones and other insect semiochemicals have been concentrated in capillary traps for thermal desorption and gas chromatographic separation. Whereas highly volatile compounds are not quantitatively retained by traps short enough to enable thermal desorption in the injector, quantitative trapping is possible on longer fused silica traps. Short traps coated with a 145 μm film of a polysiloxane were used for the quantitative determination of the constituents of a dung beetle attractant. By means of a “living detector” with the antenna of an insect as sensing element the compounds eluting from a gas chromatographic column, were screened for possible semiochemical activity.
Gas chromatographic separation of protein amino acids in four minutes
Authors: Hušek Petr , Sweeley Charles C. 
Published: May 2005

AbstractA method is presented for analysis of protein amino acids in five minutes, including derivatization. The chemical treatment involves reaction with ethyl chloroformate: if the composition of the reaction medium is optimum this reagent esterifies carboxylic groups simultaneously with derivatization of other reactive groups and the reaction is complete in seconds. The moderately polar silicone OV‐1701 was found to be a convenient liquid phase for separation of the derivatives: a five meter capillary column of internal diameter suitable for routine use was able to separate the amino acids in four minutes. Derivatization of arginine was incomplete and it failed to elute from the column.
Analysis of chemical warfare agents in water by solid phase extraction and two‐channel capillary gas chromatography
Authors: Häkkinen Vesa M. A. 
Published: May 2005

AbstractSolid phase extraction with commercial C‐18 cartridges has been applied to the analysis of some well known chemical warfare agents in water samples. Different sample pretreatment and cartridge conditioning procedures, and different extraction solvents were tested to study the optimum conditions for efficient extraction and recovery of the compounds of interest. The eluates were analyzed with a two‐channel gas chromatograph equipped with an autosampler and a retention index monitoring system.The suitability of this technique for real samples is discussed: the rapid hydrolysis of many of the compounds studied and the poor recoveries of the polar degradation products are practical limitations of the method.
Supercritical fluid extraction of polychlorinated dibenzo‐p‐dioxins from municipal incinerator fly ash
Authors: Onuska Francis I. , Terry K. A. 
Published: May 2005

AbstractThe supercritical fluid extraction of polychlorinated dibenzo‐p‐dioxins from an incinerator fly ash sample has been investigated; supercritical nitrous oxide and its mixtures with methanol and toluene were employed as mobile phases.Recoveries of individual polychlorinated dibenzo‐p‐dioxins congeners were calculated from results of analysis of 13C‐labeled dioxins by high resolution GC‐MS employing selected ion monitoring. The extraction procedure was compared with extraction in a Soxhlet apparatus, which is currently used as a standard method for removing chlorinated dibenzo‐p‐dioxins from fly ash samples: the results indicated that the time required for the extraction and clean‐up can be reduced from 24 to 2.5 hours/sample. Quantitative recovery of the chlorinated dibenzo‐p‐dioxins was achieved at μg/kg levels, the relative standard deviation was between 1.8 and 5.8%.The use of a virtually inert fluid such as pure nitrous oxide provides significant improvement over conventional extraction procedures because no solvent residue is left in the processed extract.
Some practical experiences in the use of a solventless injection system for packed column supercritical fluid chromatography
Authors: Oudsema John W. , Poole Colin F. 
Published: May 2005

AbstractThe operating characteristics of a solventless injector for packed column supercritical fluid chromatography are described. Successful operation depends on the difference between the volatilities of the analytes and the solvent or matrix being sufficient for their separation by gas purging in a thermostatted precolumn, and also on the existence of an effective re‐focusing mechanism at the head of the analytical column for the sample dissolved in liquid or supercritical fluid carbon dioxide. The latter is easily achieved in density programmed operation by stationary phase trapping at low fluid densities or phase ratio trapping by changing the temperature at low to moderate fluid densities. The solventless injector can easily accommodate sample volumes from 1–100 μl and is easily adapted for in‐line derivatization using reagents which can, after reaction, be eliminated by gas purging. For general purposes the solventless injector can be used to overcome most of the problems encountered when rotary valve loop injectors are used with small bore packed columns, and will probably replace this type of injector as the injector of choice for supercritical fluid chromatography with mobile phases of low polarity.
Studies of grass forages and their fibrous fractions by pyrolysis gas chromatography – ion trap detection
Authors: Piccaglia Roberta 
Published: May 2005

AbstractGrass forage samples with different fiber content and composition, and their fibrous fractions, have been analyzed by pyrolysis – gas chromatography with ion trap detection. The identities of the pyrolysis fragments indicated their origin to be carbohydrates, lignin, and nitrogen compounds. Comparison of the resulting quantitative data by factorial variance revealed pyrogram peaks attributable to neutral detergent fiber, cellular contents, and lignin. Quantitative pyrolysis data from these components showed the same trends as those recorded by the method of Goering and Van Soest [1].
Direct supercritical fluid extraction of nitrogenous bases from aqueous solution
Authors: Hedrick Joseph L. , Taylor Larry T. 
Published: May 2005

AbstractThe feasibility of using supercritical carbon dioxide for both static and dynamic extraction of organic bases from an aqueous matrix has been investigated. It appears that the greater the lipophilic portion of the molecule the more readily is the base extracted: triprolidine, sulfamethazine and caffeine were extracted whereas picolinic acid, succinonitrile, and nicotine were not.
Analysis of compounds of environmental concern: II. Diphenyl ethers
Authors: Lopez‐Avila Viorica , Benedicto Janet , Baldin Emi , Beckert Werner F. 
Published: May 2005

AbstractNineteen halogenated and/or nitrated diphenyl ethers (currently listed in EPA Method 8111) have been separated on a DB‐5/ DB‐1701 column pair connected to an inlet splitter and separate electron capture detectors. Retention times are included for 10 additional compounds evaluated for their suitability as internal standards or surrogate compounds for incorporation into Method 8111. Method reproducibility and linearity are discussed, and results are presented for extracts of two real samples spiked with the 19 diphenyl ethers and analyzed using the dual‐column dual‐detector arrangement.
Simulated distillation of wax samples using supercritical fluid and high temperature gas chromatography
Authors: Thomson J. S. , Rynaski A. F. 
Published: May 2005

AbstractSimulated distillation boiling range distributions have been compared for high boiling petroleum wax samples using high temperature gas chromatography and supercritical fluid chromatography. Midpoint (50 % off) temperature differences were small, and average differences between the two types of analyses were less than 6° Details of optimization of the HTGC and SFC systems and injection techniques used are reported.
Rapid analysis of coke oven gas by capillary gas chromatography
Authors: Havenga Willem J. , Rohwer Egmont R. 
Published: May 2005

AbstractA porous layer open tubular (PLOT) column has been used for monitoring the light hydrocarbons and permanent gases produced in coking plants. The method, which offers a simple alternative to traditional multi column techniques, entails a single injection on to a Carboplot 007 capillary column and simultaneous thermal conductivity and flame ionization detection. The simplified approach proposed is restricted to coke oven gas analysis: application to other gas mixtures has not been considered.The reliability of this procedure compares favorably with that of traditional methods; the technique is also much less time‐consuming: seven individual gases can be determined on‐line every fifteen minutes. Primary and secondary gas standards were used to determine response curves for the gases.The method also facilitates reliable calculation of heat values associated with the burning of the fuel gas mixtures.
Sample evaporation in conventional split/splitless GC injectors. Part 3: Retaining the liquid in the vaporizing chamber
Authors: Grob Konrad , De Martin Mirelia 
Published: May 2005

AbstractAs most sample liquids tend to pass through an empty injector insert at a speed which is too high to enable complete evaporation, movement of the liquid must be arrested before it reaches the column entrance. Stopping the liquid means deposition on to a surface; this, however, is possible only after the temperature of the surface has been cooled to (or below) the boiling point of the liquid (solvent).The performance of different means of stopping the liquid has been tested visually (by the method described in Part 2). Baffles on the wall of the injector insert had hardly any effect on evaporation: the band of liquid leaving the syringe needle performed a perfect slalorn around them. The inverted cup proved more efficient, but the best performance was obtained from a light plug of glass wool: owing to its low thermal mass, the first fibers to be met by the liquid are immediately cooled to the solvent boiling point, allowing the liquid to wet it. The sample liquid is sucked up by the glass wool, from where the sample evaporates relatively slowly, often over a period of several seconds.
Compressibility effects in packed and open tubular gas and supercritical fluid chromatography
Authors: Janssen Hans‐Gerd , Snijders Henri , Cramers Carel , Schoenmakers Peter 
Published: May 2005

AbstractThe influence of the pressure drop on the efficiency and speed of analysis in packed and open tubular supercritical fluid chromatography (SFC) is described: methods previously developed to describe the effects of mobile phase compressibility on the performance of open tubular columns in SFC have been extended to packed columns.The Horvath and Lin equation has been used to elucidate the influence of variations in velocity, diffusivity, and capacity factor along the column on the overall efficiency of packed column SFC. In packed columns, in contrast with the situation in open tubular columns, because the increase in velocity is no longer compensated by an increase in diffusion coefficients, the increase in both linear velocity and capacity factor which result from a significant pressure drop cause the plate height to increase along the column.The effect of fluid decompression along the length of the column on the speed of analysis in SFC has been studied and numerical expressions derived which enable calculation of compressibility correction factors for the plate height. Both the f1 and f2 correction factors remain very close to unity for acceptable pressure drops, which means that the pressure drop has virtually no effect on the number of plates generated per unit time for an unretained component. For retained species, the decompression of the mobile phase across the column causes the capacity factor to increase and hence leads to increased analysis times.
Use of headspace capillary GC to study the development of volatile compounds in fresh fruit
Authors: Rizzolo Anna , Polesello Andrea , Polesello Stefano 
Published: May 2005

AbstractThe composition of volatile compounds produced by fruit during growth and post‐harvest storage and ripening has been studied and the different headspace methods compared. Static and dynamic headspace sampling have been compared and evaluated according to their capacity to collect and concentrate volatiles from the atmosphere surrounding the fruits, and FID, MSD, and organoleptic detection have been compared. The results emphasize that the headspace sampling procedure selected is crucial to the performance of subsequent analysis.
The separation of enantiomers on modified cyclodextrin columns: Measurements and molecular modeling
Authors: de Vries N. Koen , Coussens Betty , Meier Robert J. , Heemels Gerlie 
Published: May 2005

AbstractThe enantiomers of 2‐chloropropionic acid methyl ester, cis‐pinane, 2‐bromoethylbenzene, 2‐bromobutane, 2‐hydroxybutane trifluoroacetyl ester, and styrene oxide have been resolved on an octakis‐(3‐O‐butyryl‐2,6‐di‐O‐pentyl)‐γ‐cyclo‐dextrin capillary column, and the separation of the styrene oxide enantiomers has also been studied on columns coated with octakis‐(3‐O‐trifluoroacetyl‐2,6‐di‐O‐pentyl)‐cyclodextrin, octakis‐(2,3,6‐tri‐O‐pentyl)‐γ‐cyclodextrin, heptakis‐(3‐O‐trifluoroacetyl‐2,6‐di‐O‐pentyl)‐β ‐cyclodextrin, and heptakis‐(2,3,6‐tri‐O‐methyl)‐β‐cyclodextrin.Thermodynamic parameters (ΔG, ΔH, and ΔS) were determined from variable temperature measurements. The inclusion complexes containing styrene oxide were also studied by molecular modeling techniques. It has been found that a combined molecular mechanics–molecular dynamics approach may be a valuable tool for rationalizing the qualitative trends observed in the experimental separation factors. For the inclusion complexes considered here it is shown that the orientation of the guest relative to the cyclodextrin host is determined by the size and polarity of the cyclodextrin.
Determination of organometallic compounds by capillar gas chromatography – inductively coupled plasma mass spectrometry
Authors: Kim Alexander , Hill Steve , Ebdon Les , Rowland Steve 
Published: May 2005

AbstractThe separation and detection of volatile organometallic compounds containing tin, iron, and nickel has been achieved using capillary GC–inductively coupled plasma–mass spectrometry (capillary GC‐ICP‐MS). Detection limits range from 3.0 to 7.0 pg/s. The presence of volatile organotin compounds in a harbor sediment has been confirmed. The retention range of the organometallic compounds analyzed by capillary GC‐ICP‐MS has been extended considerably beyond that possible in earlier studies (retention indices up to 3400).
A monomolecular pseudostationary phase for micellar electrokinetic capillary chromatography
Authors: Palmer Christopher P. , Khaled Maha Y. , McNair Harold M. 
Published: May 2005

AbstractA highly stable pseudostationary phase has been synthesized and evaluated for use in micellar electrokinetic capillary chromatography (MECC). Sodium 10‐undecylenate has been oligomerized to form a micelle‐like structure following the procedure of Durairaj et al. [1].The stability of this structure renders it suitable for use with mobile phases containing relatively high percentages of organic modifiers, enabling the separation and detection of hydrophobic analytes such as alkyl phthalates and polynuclear aromatic hydrocarbons (PAHs) which are difficult to analyze by conventional micellar electrokinetic chromatography. In addition to demonstrating the utility of this structure for the analysis of hydrophobic analytes, the electrophoretic and chromatographic properties of the new phase have been investigated.
Identification of pentacyclic triterpenes by GC‐MS‐MS
Authors: Hazai Istvan , Galvez‐Sinibaldi Alfredo , Philp R. Paul 
Published: May 2005

AbstractThe development of tandem mass spectrometry (MS‐MS) and its combination with gas chromatography (GC‐MS‐MS) has greatly enhanced our ability to analyze exceedingly complex mixtures from a wide variety of sources, including fossil fuels. This paper describes a comparison of the conventional electron impact (El) mass spectral fragmentation patterns, obtained in the MS‐MS precursor – product mode, of three oleanane isomers and one ursene, all of which are used as indicators of higher plant input to the sedimentary environmentResults show that El and collision‐activated dissociation (CAD) spectra are most similar at collision energies between −15 and −20 eV.The presence of methyl substituents in these pentacyclic terpenes plays an important role in the process of ring fragmentation: the daughter spectra of the M – 15 fragments can be used to obtain structural information, such as the positions of the double bonds.
Improved SFE recovery of trace analytes from liver using an integral micrometering valve–SPE column holder assembly
Authors: Maxwell Robert J. , Parks Owen W. , Piotrowski Edwin G. 
Published: May 2005

AbstractA novel integral restrictor–collector has been designed for use with a conventional supercritical fluid extraction (SFE) apparatus. The assembly reduces the path length between a micrometering valve and collector (a solid phase extraction (SPE) column), obviating the need for the complicated tubing and connectors usually associated with such devices. Also described is a heating‐block assembly which encases the micrometering valve and provides uniform heating of the valve during extraction.The valve–SPE column assembly was part of a system used to perform the first reported SFE multi‐residue drug recovery from fortified liver. Extractions used carbon dioxide pressurized to 690 bar as the supercritical fluid. Flow rates of expanded gas through the SPE columns were 3–4 L/min with concomitant quantitative trapping of the analytes on the sorbent bed. After SFE the three nitrobenzamide antimicrobial drug residues from the liver were eluted from the SPE columns by off‐line analysis. The results demonstrated that losses of trace level analytes in tissue may be significantly reduced by including an integral metering valve‐collector assembly as part of the SFE apparatus.
The effects of inlet liner configuration and septum purge flow rate on discrimination in splitless injection
Authors: Hinshaw John V. 
Published: May 2005

AbstractAn unmodified split/splitless inlet system using forward‐pressure controlled pneumatics was operated in splitless injection mode with several inlet liners under a range of septum purge flow rates. The relative recovery (discrimination) of hydrocarbons ranging from n‐C8 to n‐C20 depended strongly upon the injected sample volume with open‐ended liners at high septum purge flow rates of e.g. 50 mL/min. Little or no discrimination was observed at septum purge flows of 2–3 mL/min. The same inlet was also operated in a back‐pressure regulated configuration that produced mass discrimination similar to that observed with the higher septum purge flows in the forward‐pressure configuration. An inlet liner with a restricted inlet and outlet gave mass‐discrimination levels independent of septum purge flow rate, but in the reverse sense of that observed with open‐ended liners. Preferential volatile‐component losses out of the inlet liner to the septum purge vent are principally responsible for the observed mass discrimination with openended liners, while mass‐dependent losses with doubly‐restricted liners seem due to slow sample evaporation.
An amylopectin tris(phenylcarbamate) chiral stationary phase for high performance liquid chromatography
Authors: Félix Guy , Zhang Tong 
Published: May 2005

AbstractAmylopectin tris(phenylcarbamate) has been evaluated as a chiral stationary phase for HPLC; the influence on its cptical resolving capabilities of mobile phase composition and nature of the alcohol used as modifier has been studied. Separation and resolution of twelve arylalcohol racemates were examined. In most instances, the stationary phase exhibited high optical resolving capacity.
Use of modifiers in on‐line and off‐line supercritical fluid extraction
Authors: Levy Joseph M. , Dolata Lori , Ravey Robert M. , Storozynsky Eugene , Holowczak Kathy A. 
Published: May 2005

AbstractFor many applications using supercritical fluid extraction (SFE), modifiers may be required.This paper will present some findings regarding the use of various modifiers including methanol, hexane, acetone, chloroform, dichloromethane, toluene, and tributylphosphate, in on‐line and off‐line SFE with cryogenic adsorbent trapping. The specific applications involved the extractions of petroleum hydrocarbons and pesticides from naturally incurred soils.
Inserts providing complete sample evaporation above the column entrance in vaporizing GC injectors
Authors: Grob Konrad , Wagner Christoph 
Published: May 2005

AbstractCompleteness of sample evaporation in conventional vaporizing injection is a problem for many samples and calls for measures to arrest the sample liquid in the space between the needle exit and the column entrance. A visual testing procedure reveals that a small plug of loose glass or quartz wool ensures complete evaporation in all instances. Obstacles built into the liner also stop liquid, provided they force the sample to pass through narrow channels. Other important design characteristics concern access to the narrow channel. Evaporation in a packed insert usually occurs from a surface, whereas the sample hardly touches surfaces in the instance of an insert with obstacles. Evaporation from a packing is, in fact, more reliable, but creates more problems concerning inertness.