bluuebunny/crossref_metadata_2025_split huggingface dataset:
Chiral stationary phases for capillary gas chromatography: Towards higher selectivity and stability
Authors: Frank H. 
Published: May 2005

AbstractThermal stability and enantioselectivity of chiral polysiloxane stationary phases for gas chromatography depend upon the composition and purity of the polymer matrix, its functional groups, the chiral selector, and the pretreatment of the inner surface of the capillary. Under proper conditions, narrow‐bore capillaries can be prepared which may be used up to 300 °C for short times. Crosslinking of the phases is achieved by heating.
Unified capillary chromatography
Authors: Ishii D. , Niwa T. , Ohta K. , Takeuchi T. 
Published: May 2005

AbstractThe idea of unified capillary chromatography is described. Different‐mode separations could be carried out by changing the column temperature and the pressure by using a single system. Gas chromatographic separation of aromatic hydrocarbons followed by supercritical fluid chromatographic separation of styrene oligomers was carried out in series in a single chromatographic run.
Coupling miniaturized liquid chromatography to capillary gas chromatography (micro‐LC‐CGC): Possibilities of reversed phase LC
Authors: Duquet D. , Dewaele C. , Verzele M. , McKinley S. 
Published: May 2005

AbstractRetention gaps with different polarity treatments were evaluated for reversed phase solvents. Aminopropyl‐ and cyanopropyl‐deactivated retention gaps showed the best results for methanol‐water mixtures. A reversed phase packed fused silica capillary LC column is connected on‐line with a capillary gas chromatography column. The combination was used for the analysis of diazepam in urine. Volume overloading on packed fused silica columns without loss of too much efficiency was demonstrated for propranolol.
Enantiomer separation with capillary gas chromatography columns coated with cyclodextrins. Part I: Separation of enantiomeric 2‐substituted propionic acid esters and some lower alcohols with permethylated β‐cyclodextrin
Authors: Venema A. , Tolsma P. J. A. 
Published: May 2005

AbstractThe applicability of permethylated β‐cyclodextrin as an enantioselective stationary phase for capillary gas chromatography has been investigated. Attention has been paid to its phase transitions in a temperature range of 40–200°C. The enantiomer separation of 2‐substituted propionates and some lower alcohols illustrates the pronounced selectivity of the permethylated β‐cyclodextrin relative to molecular geometry.
Analysis of propellant stabilizer components via packed and capillary supercritical fluid chromatography/Fourier transform infrared spectrometry
Authors: Ashraf‐Khorassani M. , Taylor L. T. 
Published: May 2005

AbstractThe separation of model mixtures of nitrated diphenylamine and nitrated aniline via supercritical fluid chromatography employing both capillary and packed columns is described. With highly deactivated stationary phases each mixture could be separated with 100% CO2 pressure programmed. Peak identification and peak purity were afforded by on‐line Fourier transform infrared spectrometric detection. Nitrosoaniline derivatives were observed via FTIR to have been converted to nitro derivatives on storage.
High resolution gas chromatography/mass spectrometry analysis of the environmental pollutants methylnitronaphthalenes
Authors: Arey J. , Zielinska B. 
Published: May 2005

AbstractWe report the linear retention indices of the 14 methylnitro‐naphthalenes on three high resolution capillary columns and their electron impact mass spectra. The analyses of the methylnitro‐naphthalenes in an ambient air sample by gas chromatography/mass spectrometry with multiple ion detection utilizing 5% phenylmethylsilicone, 50% phenylmethylsilicone, and smectic columns are shown.
A new high temperature gas chromatograph incorporating a temperature programmable direct injector
Authors: Berg J. R. 
Published: May 2005

AbstractA high temperature gas chromatograph has been developed which is capable of operating at column oven temperatures up to 500°C. In addition, the detector can operate at temperatures up to 500°C, and the injector up to 450°C. The injector on this instrument is a temperature programmable direct injector, designed specifically to introduce labile or high molecular weight samples into the GC without molecular weight discrimination. The design of this GC and injector will be described, and high temperature applications will be discussed.
An application of factorial design to the development of fused silica capillary columns
Authors: Hyver K. J. , De Veaux R. D. 
Published: May 2005

AbstractStationary phase crosslinking conditions for fused silica capillary columns were optimized with the use of a factorial design experiment. This experimental strategy was chosen because it provided for the determination of two‐factor interactions. A predictive model was developed for the desired chromatographic performance parameters as a function of the variables of the crosslinking reaction. Confirmatory experiments proved the usefulness of the mathematical model which resulted in the production of capillary columns of superior performance with significant improvements in reproducibility.
Sampling techniques for SFC using peak focusing by pressure and/or temperature programming
Authors: Schomburg G. , Roeder W. 
Published: May 2005

AbstractIn analogy to the focusing effective in capillary GC, performed with temperature programming but also with sectional cooling of the column inlet as in multidimensional capillary GC, peak focusing can easily be attained in SFC by adjustment of the mobile phase pressure as well as the column temperature. This may be of practical use in connection with sampling techniques giving poor, i.e. broad and unsymmetrical, peak shapes. Such disturbances may occur, for example, in time controlled valve sampling over longer switching times. Generally, all other negative influences on peak shape can be suppressed or compensated by trapping within the column inlet. Special trapping devices and “retention gaps” may also be coupled to the column inlet in order to create narrow starting plug widths. Positive pressure (density) and negative temperature programs give rise to peak compression besides the increase of peak capacity of the separation.
Capillary gas chromatographic analysis of amino acids in geological environments with electron capture detection
Authors: Liu De‐Ming 
Published: May 2005

AbstractStudies have been performed on the analysis of 21 amino acids using a fused‐silica open tubular (FSOT) capillary column, and electron‐capture detection (ECD) or flame‐ionization detection (FID). It was shown with the N(O)‐heptafluorobutyryl (HFB) amino acid isobutyl esters that the ECD response was several hundred times more sensitive than the FID response. The relative standard deviation (RSD) of retention relative to norleucine is determined with the ECD. RSD values for all N(O)‐HFB amino acid isobutyl esters are relatively small (≦ 0.5%). This method has been successfully applied to trace analysis of most of the amino acids from fossil brachiopods and black shales.
Use of computerized pattern recognition of triglyceride profiles in monitoring SCF‐CO2 extraction of fatty oils
Authors: Vasconcelos A. M. P. , Gonçalves M. , de Azevedo E. J. S. Gomes , da Ponte M. Nunes , das Neves H. J. Chaves 
Published: May 2005

AbstractHigh pressure extraction of vegetable fatty oils by supercritical fluid carbon dioxide was investigated. Pressures from 9 to 20 MPa at 40°C were used. The extracts were monitored by high temperature capillary gas chromatography for sterol and tri‐glyceride composition. The quality of the extracted oils was evaluated by numerical taxonomy methods. The extraction products compared well with the characteristics of commercial fatty oils of the same vegetable origin. No significant qualitative variation was detected in the pressure range studied.
Ultra‐sensitive UV detection in micro separation
Authors: Chervet J. P. , Ursem M. , Salzmann J. P. , Vannoort R. W. 
Published: May 2005

AbstractMost UV detectors used in micro separation techniques today suffer from an enormous loss in sensitivity due to the small cell volume necessary to avoid peak dispersion. Flow cells with volumes between 10‐100 nl are normally constructed of fused silica tubing. With typical path lengths of between 50‐320 μm, a tremendous loss in sensitivity results, consistent with Beer‐Lambert's law.We have successfully constructed an ultrasensitive UV flow cell. Its total volume does not exceed 90 nl and yet its optical path length is nearly 2 cm (20,000 μm). Due to its special design, dead volume is minimized and is comparable to that of a 3 nl capillary flow cell (on‐column). Sensitivity enhancement of 100‐500 times can easily be realized in comparison with on‐column detection. The potential of this ultra‐sensitive UV flow cell in micro separations is illustrated by applications using Capillary LC and Pakked Capillary SFC.
Determination of amino acids in urine by gas chromatography
Authors: Moodie I. M. , Hough B. J. , Labadarios D. 
Published: May 2005

AbstractThis report describes a convenient means of reducing the complex matrix which is responsible for interference during gas chromatographic determination of amino acids in urine. The pre‐chromatographic clean‐up employs the principle of solid phase extraction using bonded silica incorporating cation exchange groups. This approach avoids the detrimental effects on amino acid recoveries associated with resin‐based cation exchangers. In spite of significant reduction in the complexity of chromatograms, only the high efficiency and resolving power offered by the analytical capillary column (e. g. fused silica open tubular, FSOT) is sufficient for quantitative and analysis of amino acids in urine. Reproducibility data from the complete procedure are determined, coefficients of variation (CV) for most amino acids being better than 5% with a mean recovery of 96%.
Sequential determination of sugar units in reducing disaccharides by capillary gas chromatography/Fourrier‐transform infrared spectroscopy
Authors: das Neves H. J. Chaves , Riscado A. M. V. 
Published: May 2005

AbstractConversion of disaccharide reducing units into the corresponding methoximes followed by their reduction with NaBH4CN to the corresponding deoxy(methoxyamino)alditol glycosides (RCH2‐NHOCH3) introduces a constitutional asymmetry in the sugar molecule. After methylation of the resulting compounds, cleavage of the glycosidic bonds is carried out by BF3‐ catalyzed methanolysis, affording permethylated O‐methylglycosides and permethylated deoxy(methylmethoxyamino)alditols with a free −OH corresponding to the position of the glycosidic bond. Identification of the reducing moiety is achieved by GC‐FTIR and computerized retrieval of library FTIR spectra.
A review of quantitative ion exchange, high performance liquid and gas chromatographic analysis of amino acids in physiological fluids
Authors: Moodie I. M. , Shephard G. S. , Labadarios D. 
Published: May 2005

AbstractMethodologies for quantitative analysis of amino acids in physiological fluids based on classical ion exchange, high performance liquid chromatography, and gas chromatography are analyzed. As judged by the relative number of reports on these techniques, it appears that classical ion exchange continues to be the main method of choice for amino acid determinations and only limited advantage has been taken of the benefits (e.g. lower capital outlay and running costs and shorter analysis times) offered by other techniques. More importantly, however, there appears to be insufficient quantitative evaluation of the methodologies used. As a result, the validity of many reports based on data from amino acid analysis of physiological samples may be questioned.
Direct enantiomer separation of chiral γ‐lactones from food and beverages by multidimensional gas chromatography
Authors: Mosandl A. , Hener U. , Hagenauer‐Hener U. , Kustermann A. 
Published: May 2005

AbstractChiral γ‐lactones from the raw flavor extract of strawberries and some commercially available fruit‐containing food and beverages were stereoanalyzed directly by multidimensional gas chromatography (MDGC) employing heart‐cutting techniques from DB‐1701 as the preseparation column onto heptakis (3‐O‐acetyl‐2,6‐di‐O‐pentyl)‐β‐cyclodextrin as the chiral stationary phase.
Dual channel detection–diode array and mass spectroscopy (El or Cl)–in HPLC
Authors: Sandra P. , Courselle P. , Steenbeke G. , Schelfaut M. 
Published: May 2005

AbstractSimultaneous recording of UV and mass spectra (electron impact or chemical Ionization) in conventional HPLC is described. The LC eluent is divided into two parts; one is directed into a diode array detector and the other is introduced into the mass spectrometer via a particle beam interface. The analysis of the steroid esters of a pharmaceutical formulation illustrates the possibilities of dual channel (DAD‐MS) HPLC detection.
On‐line SFC/FT‐IR analysis of agriculturally‐related compounds
Authors: Shah S. , Taylor L. T. 
Published: May 2005

AbstractSeveral agricultural compounds which are used as herbicide precursors have been analyzed by SFC and are detected on‐line via a flow cell FT‐IR interface. A mixture of ureas is separated on a microbore packed column; while a mixture of benzamides and anilides and a mixture of sulfonamides are separated on capillary columns. The use of 100% CO2 as the mobile phase enables an infrared spectrum of each eluting analyte to be obtained on‐line with good signal to noise ratio. The urea mixture is also separated with a conventional cyanopropyl bonded phase analytical scale packed column using a methanol‐modified CO2 mobile phase and UV detection. The separations achieved with and without modifier are compared.
Determination of volatile amines in drug substances by capillary gas chromatography
Authors: de Haan P. E. , de Jong D. , van den Berg J. H. M. , Kruse C. G. 
Published: May 2005

AbstractThe determination of small, water soluble amines such as aziridine and 2‐chloroethylamine, in drug substances at trace levels is described. After removal of the bulk of the drug substance by extraction or precipitation, derivatization with acid chlorides is performed. In a two‐phase (water‐organic solvent) system, this derivatization reaction is accomplished almost simultaneously with the extraction of the product to the organic layer. The organic layer is analyzed by gas chromatography using on‐column injection and selective detection. Detection limits are approx. 0.2 mg/kg for aziridine and approx. 0.5 mg/kg for 2‐chloroethylamine.
Some applications of capillary gas chromatography in clinical chemistry
Authors: Liebich H. M. , Wahl G. 
Published: May 2005

AbstractProfile analysis using capillary gas chromatography is applied in clinical chemistry to detect metabolic abnormalities. Examples are the increase of the urinary excretion of aromatic acids carrying a 4‐hydroxyl group and the decrease of hippuric acid in liver cirrhosis, and the elevated concentrations and excretions of dicarboxylic, oxocarboxylic, and hydroxycarboxylic acids in diabetes mellitus. Gas chromatographic quantitations, in some instances using mass selective detection, are performed on clinically relevant constituents. An example is the investigation of plasma and urinary hippuric acid and 3‐carboxy‐4‐methyl‐5‐pro‐pyl‐2‐furanpropionic acid in different stages of renal diseases.
Dynamic headspace analysis of trace volatile components in polymeric materials by wide bore capillary gas chromatography
Authors: Tsuge S. , Kuriyama K. , Ohtani H. 
Published: May 2005

AbstractA novel dynamic headspace gas chromatographic system equipped with a wide bore capillary column was constructed for direct analysis of less volatile components in polymeric materials such as coating paints. With this system, the determination of typical paint additives such as hindered amine light stabilizers and ultraviolet absorbers could be carried out within a short time.
The potential of on‐line flame photometric detection in microcolumn liquid chromatography
Authors: Kientz Ch. , Verweij A. , de Jong G. J. , Brinkman U. A. Th. 
Published: May 2005

AbstractThe potential of an interface for the on‐line coupling of microcolumn liquid chromatography (LC)and a flame photometric detector (FPD) has been further investigated. With the micro‐LC/FPD system, relatively high‐molecular‐weight polar compounds such as cyclic adenosine monophosphate, guanosine monophos‐ phate, glucose monophosphate, fructose monophosphate, and phytic acid were separated and selectively detected. In order to increase the sensitivity, on‐line preconcentration with a microprecolumn inserted in the rotorof a Valcovalve has been applied. Preliminary results have shown that an injection volume of at least 500 1‐11 water containing organophosphorus acids at a 5–50 ng/rnl concentration level is possible.
Polar solvents for the desorption of a liquid chromatographic precolumn coupled on‐line with a capillary gas chromatograph
Authors: Vreuls J. J. , Cuppen W. J. G. M. , Dolecka E. , Maris F. A. , de Jong G. J. , Brinkman U. A. Th. 
Published: May 2005

AbstractCoupling column liquid chromatography and gas chromatography on‐line is becoming more important in analytical chemistry. Especially when large amounts of polar solvents can be introduced into the gas chromatograph without any problem, the technique will offer new possibilities. With a DPTMDS retention gap, evaporation rates and flooded zones of some solvents have been determined. Two modes of operation using partially concurrent solvent evaporation conditions are discussed: (1) injecting a sample via a loop of an LC valve followed by introduction into the gas chromatograph with an LC pump; (2) trace enrichment on a precolumn followed by on‐line desorption with n‐propanol into the gas chromatograph. Preliminary results for a splitter system, inserted between the retention gap and the analytical column which allows a considerable increase of the evaporation rate are also presented.
Applications of gas chromatography with an atomic emission detector
Authors: Wylie P. L. , Quimby B. D. 
Published: May 2005

AbstractAn atomic emission detector for gas chromatography has been developed which is, in principle, capable of detecting selectively any element (except helium) which can elute from a gas chromatographic column. Software methods have been developed so far for 23 elements and on isotope, including all of the organic elements along with mercury, lead, tin, silicon, and deuterium. Element‐specific analyses are shown for several petroleum, environmental, and aroma samples. A table for the detector's element‐specific detection limits, selectivities, and linear dynamic ranges is given for 12 elements and deuterium.
Analysis of C1‐ and C2‐halocarbons in ambient air from remote areas using stainless steel canister sampling, cold trap injection HRGC, and a static calibration technique
Authors: Müller S. , Oehme M. 
Published: May 2005

Abstract5 ml air samples from 1.6 l stainless steel canisters were cryogenically preconcentrated before gas chromatographic separation on a thick‐film capillary using a home‐made cryotrap. Quantification in the 10–500 ppt range was carried out with an electron capture detector. Problems during the cryotrap step were caused by carrier gas contamination, water and CO2 content of the sample, and a non‐optimal heat desorption rate. Their elimination is described in detail. Compound losses by wall adsorption on stainless steel surfaces were observed when dry gases were used for standard generation. A static multipoint calibration technique using humidified He was developed allowing a precise standard generation down to 100 ppt. The concentration changes in the stainless steel canisters could be neglected over a storage period of at least 1 month as long as a sufficient degree of humidity was present. The overall reproducibility of the quantification and calibration technique is in the order of 1–2% for concentrations between 100–400 ppt when daily recalibrations are carried out.
Packing material activity in packed capillary column SFC
Authors: De Weerdt M. , Dewaele C. , Verzele M. , Sandra P. 
Published: May 2005

AbstractSeveral commercially available and home‐made reversed phase packing materials packed in capillary columns are evaluated for SFC with pure CO2 as mobile phase. Anilines and polycyclic aromatic hydrocarbons are used as test mixture. Some “on column endcapping” experiments are evaluated.
Characteristics of an amperometric detector for capillary HPLC
Authors: Ruban V. F. 
Published: May 2005

AbstractThe main characteristics of a dual‐electrode amperometric detector with a cell of the “cylinder‐in‐flow” type with a working wire electrode have been investigated. The effective cell volume is 10–40 nl in a system with 0.2–0.4 mm i.d. packed fused‐silica columns. Extra‐column spreading at the optimum elution rate does not exceed 0.005 μl2. The linear range is 103 at a relative standard deviation of 0.009. The low noise level (2–3 pA) facilitates determination of electro‐active substances. The detection limit for catecholamines is of the order of tenths of a femtomole.
Quantitative analysis of phospholipids by HPLC with a light scattering evaporating detector – application to raw materials for cosmetic use
Authors: Becart I. , Chevalier C. , Biesse J. P. 
Published: May 2005

AbstractA method is described for separation and quantitative analysis of various phospholipids and sphingolipids by high performance liquid chromatography on a silica gel column with a mobile phase consisting of chloroform, methanol, and ammonium hydroxide. Gradient elution is necessary. A study of the light scattering evaporative detector response is presented. The method has been applied to the analysis of phospholipids of a commercial soja lecithin and a pig brain extract.
SFC in analysis of aromatic plants
Authors: Manninen P. , Riekkola M.‐L. , Holm Y. , Hiltunen R. 
Published: May 2005

AbstractCapillary SFC was applied to the analysis of Some plant volatile oils. The results were compared with those obtained by capillary GC. For thyme oil, SFC without derivatization gave about the same percentage composition of the main compounds as CGC with silylation, thus eliminating one working step. For a complex mixture of peppermint oil or basil oil, SFC seems to give more reliable quantification than CGC, especially for oxygenated compounds. However, the separation efficiency of CGC for monoterpene hydrocarbons was, as expected, much better than that of SFC.
Separation of metal complexes by on‐line coupled LC‐GC
Authors: Lukkari P. , Hannuksela J. , Mattinen M.‐L. , Virolainen M. , Häkkinen Vera M. A. , Riekkola M.‐L. 
Published: May 2005

AbstractThe on‐line coupled LC‐GC technique was applied to the analysis of several metal chelates of N,N‐diethyldithiocarbamic acid. A 10‐port valve interface was used to couple the LC and GC instruments. Conditions during sample transfer into the GC gave fully concurrent solvent evaporation. The chelates investigated were separated with a short apolar fused silica column. LC preseparation was made with cyano or amino phases using a hexane/dichloromethane mixture as eluent. On‐line LC‐GC combination seems to be very suitable for the separation of the metal chelates studied.
Direct resolution of racemic compounds on chiral microbore columns by sub‐ and supercritical fluid chromatography
Authors: Gasparrini Francesco , Misiti Domenico , Villani Claudio 
Published: May 2005

AbstractFast resolutions of racemic compounds (sulfoxides, amino alcohols, and α‐methylarylacetic acids derivatives) were achieved on a chiral microbore column using carbon dioxide and a polar methanol/dioxane modifier. The stationary phase used in this study contains the 3,5‐dinitrobenzoyl derivative of R,R(−)‐1,2‐diaminocyclohexane (DACH‐DNB) as the chiral moiety, anchored to a silica gel surface by covalent bonds. Both thermodynamic and kinetic separation performances were improved by using a super‐ or subcritical carbon dioxide mobile phase (SFC, SubFC).