bluuebunny/crossref_metadata_2025_split huggingface dataset:
Determination of the cephalosporin Ro 13‐99041 in plasma, urine, and bile by means of ion‐pair reversed phase chromatography
Authors: Trautmann K. H. , Haefelfinger P. 
Published: May 2005

AbstractAn HPLC method has been developed for the determination of the cephalosporin antibiotic Ro 13‐9904 in plasma, urine, and bile of dogs and of human volunteers using the technique of ion‐pair chromatography with a LiChrosorb RP‐18 column. The three mobile phases employed contained tetrapentyl‐, tetraoctyl‐ and hexadecyltrimethyl‐ammonium bromide, respectively, as lipophilic counterions. The chromatographic conditions chosen allowed simple and rapid sample preparation. Plasma was deproteinized with ethanol and the supernatant was directly injected onto the column; urine and bile were diluted with mobile phase and injected without any purification. The detection limit for the cephalosporin was about 0.5 μg/ml for plasma samples and approximately 5 μg/ml for bile and urine.
Improved automated simultaneous determination of isosorbide dinitrate and its metabolites in plasma by capillary column gas chromatography
Authors: Lutz D. , Rasper J. , Gielsdorf W. , Settlage J. A. , Jaeger H. 
Published: May 2005

AbstractAn automated specific and sensitive method for the simultaneous determination of isosorbide dinitrate and its metabolites isosorbide‐2‐mononitrate, isosorbide‐5‐mononitrate, isomannide mononitrate, and isoidide mononitrate at concentrations down to 0.5, 1, 3, 2, and 2 ng/ml, respectively, in human plasma is described. The procedure involves the extraction of the drug and its metabolites together with their internal standards isomannide dinitrate and o‐nitrobenzyl alcohol from plasma with dicholromethane.The analysis is carried out by fused silica capillary gas chromatography using a 63Ni‐electron capture detector. The method is applied to the pharmacokinetics of isosorbide dinitrate in humans.
An approach to high‐speed micro‐HPLC
Authors: Jinno Kiyokatsu 
Published: May 2005

AbstractThe possibility of high‐speed micro‐HPLC has been investigated using a short micro‐column (35 mm × 0.5 mm i.d.) packed with 3 μm ODS particle. The results indicate that this approach has considerable potential for good separations with short analysis time. A typical example shows only three minutes is required with a plate count of 3,800 to separate seven PAHs.
Determination by MS‐MS of 1,1‐dichlorodimethyl sulfone from pulp mill bleach plant effluents in aquatic organisms
Authors: Lindström Krister , Schubert Ralf 
Published: May 2005

AbstractGas chromatography (GC) with electron capture detection (ECD), GC combined with mass spectrometry (MS), GC with multi‐stage mass spectometry (MS‐MS), and direct inlet MS‐MS have been used to determine 1,1‐dichlorodimethyl sulfone (DDS) in aquatic organisms in the receiving waters outside a pulp mill bleach plant. Both GC‐MS‐MC and direct inlet MS‐MS of tissue extracts of fish and mussel appear to be sensitive, selective, and rapid analytical techniques for the determination of DDS.
Determination of serum metabolic profiles of bile acids by microcolumn liquid chromatography/laser‐induced fluorescence
Authors: Andreolini F. , Beale S. C. , Novotny M. 
Published: May 2005

AbstractA method for the determination of individual free and conjugated bile acids in serum using microcolumn liquid chromatography coupled with a laser‐induced fluorescence detector is described. Bile acids are separated into free/glycine‐conjugate and taurine‐conjugate fractions using a Sep‐Pak SIL cartridge. The taurine‐conjugated bile acid fraction is subjected to enzymatic hydrolysis. Subsequently, free and conjugated bile acids are labeled using 4‐(bromomethyl)‐7‐methoxycoumarin as a fluorogenic reagent, producing stable derivatives that can be excited by the 325 nm line of a He/Cd laser. Prior to their fluorimetric detection, the individual components of a bile acid serum profile are separated by reversed‐phase microcolumn liquid chromatography.
Retention prediction of large and condensed polycyclic aromatic hydrocarbons in reversed‐phase microcolumn liquid chromatography with diphenylsilica stationary phase
Authors: Jinno K. , Katoh T. , Okamoto M. , Fetzer J. C. , Biggs W. R. 
Published: May 2005

AbstractThe retention behavior of condensed large polycyclic aromatic hydrocarbons has been investigated with diphenylsilica stationary phases in reversed‐phase microcolumn liquid chromatography. The results were correlated with two parameters which indicate size and shape of the molecules. Since the resulting equation can be used for retention prediction of large polycyclic aromatic hydrocarbons, computer‐assisted “standardless” identification is accomplished for “unknown” compounds contained in the standard.
Analytical characteristics of combined gas chromatographic systems: Packed precolumn‐open tubular column
Authors: Berezkin V. G. , Popova T. P. , Korolev A. A. , Shiryaeva V. E. , Vasin L. S. , Lipavskii V. N. 
Published: May 2005

AbstractThe peculiarities of the flow splitting technique for sample injection into a capillary column have been discussed. A comparative investigation of reproducibility of the analytical results obtained for two gas chromatographic systems using flow splitting [1) sample injector‐packed predolumn‐splitter‐open tubular capillary column and (2) sample injector‐splitter‐open tubular capillary column] has been carried out. It was experimentally shown that the first system ensures considerably better reproducibility for the results concerning the composition of the analyzed mixtures. Other advantages of the first system are also discussed.
On column injection‐dual channel analysis of essential oils
Authors: Bicchi C. , Frattini C. , Nano G. M. , D'Amato A. 
Published: May 2005

AbstractA system to analyze a complex mixture simultaneously on two different columns after one single on‐column injection is described. The splitting device, the possibilities of component identification by searching in a data base for Kovats indices on two different polarity stationary phases, and a practical example of an essential oil analysis are presented.
Multi‐element selective radio frequency plasma detector for capillary gas chromatography
Authors: Skelton R. J. , Markides K. E. , Farnsworth P. B. , Lee M. L. , Yang F. J. 
Published: May 2005

AbstractA radio frequency plasma detector for element specific detection in gas chromatography is described. The detector is comprised of a radio frequency (300 kHz) discharge between electrodes in helium, and utilizes a low‐resolution emission spectrometer to monitor selected spectral emission lines produced when the helium discharge decomposes and excites the atomic constituents in the chromatographic column effluent. The spectrometer is tuned to an atomic emission line in the near‐infrared portion of the spectrum, and the emission intensity from the discharge region of a selected line is used to monitor the concentration of the element producing that line. Acceptable detector sensitivity was achieved by the use of a high‐throughput optical system. Selectivity was achieved by a combination of correct line selection, plasma and carrier gas purification, and plasma gas doping.
Quality test of a mechanical switching valve for two‐dimensional open tubular gas chromatography
Authors: Adam S. T. 
Published: May 2005

AbstractA commercially available mechanical micro switching valve has been tested for inertness. The test mixtures used were a modified Grob test and a solution consisting of eight typical aroma compounds, both at the 2‐ng level. Cryogenic focusing of the sample after chromatography including one passage through the valve revealed that irreversible interaction of some test substances with valve components was rather small. A composite main peak of a chromatogram from a fruit juice aroma exhibiting a “mixed odor” was selectively transferred (heart‐cutting) to a second column and resolved into three peaks. GC‐GC/sniffing assigned a minor peak to a substance formerly hidden under the composite peak. Separate heating of the valve during temperature programming of the column was found to be unnecessary.
Analysis of pharmaceuticals and other solutes of biochemical importance by supercritical fluid chromatography
Authors: White C. M. , Gere D. R. , Boyer D. , Pacholec F. , Wong L. K. 
Published: May 2005

AbstractThe feasibility of using supercritical fluid chromatography (SFC) for analysis of polar and/or ionic analytes of interest to the pharmaceutical industry is described. Specifically, the analyses of cyclopsporin (a cyclic undecapeptide), several ionophores, and a group of fat‐soluble vitamins are illustrated. The separation of group of fat‐soluble vitamins is evaluated on two bonded stationary phases, DB‐5 (95% dimethyl‐5%‐diphenylpolysiloxane) and DB‐WAX (Carbowax 20M type, “bonded”). Lastly, a new restrictor technology known as a converging‐diverging restrictor is described.
Analysis of volatile fatty acids in biological specimens by capillary gas chromatography
Authors: Traitler H. , Fleming S. E. , Koellreuter B. 
Published: May 2005

AbstractA method was developed to analyze and quantitate volatile fatty acids such as acetic, propionic, butyric, iso‐butyric, valeric, and iso‐valeric acid from samples of biological origin. A capillary column system including an automatic on‐column injection device as well as a precolumn of larger internal diameter than the analytical column was elaborated for this purpose.In order to obtain well resolved and correctly quantifiable chromatographic peaks it turned out to be essential to work under acidic/aqueous conditions. To achieve a better sample transfer into the chromatographic system an organic solvent had to be used together with the aqueous milieu, thus improving wetting properties of the liquid sample plug introduced into the column. Cold on‐column injection was applied in order to avoid discrimination of the various acids due to sample splitting and the automatic technique was chosen in view of the large number of samples from biological extractions which had to be analyzed.
Polysaccharide derivatives as chiral stationary phases in HPLC
Authors: Okamoto Yoshio , Kaida Yuriko 
Published: May 2005

AbstractTwenty different tris(phenylcarbamate)s of cellulose were synthesized and evaluated as chiral stationary phases for HPLC. Optical resolving power of the tris(phenylcarbamate)s depends on the substituents introduced on the phenyl groups. Optical resolving abilities of amylose tris(phenylcarbamate)s were also evaluated. In most cases, either cellulose tris(3,5‐dimethylphenylcarbamate) or amylose tris(3,5‐dimethylphenylcarbamate) exhibited the highest optical resolving ability. Aralkylcarba‐mates such as benzyl‐ and 1‐phenylethylcarbamates of cellulose and amylose were also tested as chiral stationary phases. (S)‐1‐Phenylethylcarbamate of amylose showed a high optical resolving power.
Capillary zone electrophoresis of biological substances with surface‐modified fused silica capillaries with switchable electroosmotic flow
Authors: Smith Joel Tim , Rassi Ziad El 
Published: May 2005

AbstractA surface modification has been developed which yields fused silica capillaries with switchable electroosmotic flow (anodal/cathodal). The capillary surface is a composite material consisting of unreacted silanol groups, a layer of positively charged quaternary ammonium functions, and a hydrophilic layer of long polyether chains. Because of the presence of positively and negatively charged groups, the net charge of the capillary surface can be varied from positive to negative by changing the pH of the running electrolyte, thus enabling manipulation of the magnitude and direction of the electroosmotic flow. The long polyether chains were effective in shielding biomacromolecules from the charged inner surface of the capillary, thus minimizing electrostatic interaction of the solutes with both unreacted silanols and the quaternary ammonium groups which had been introduced. As a consequence, high separation efficiencies were achieved with proteins, nucleotides, and a series of acidic oligosaccharides.
GC‐MS separation and quantitation of 3‐carboxy‐4‐methyl‐5‐propyl‐2‐furanpropionic acid and hippuric acid from plasma of patients with renal failure: Application to blood purification methods
Authors: Liebich Hartmut M. , Reichenmiller Anna‐Maria , Wahl Hans‐Günther , Tetschner Birgid , Risler Teut , Eggstein Manfred , Quellhorst Eduard 
Published: May 2005

AbstractSolid‐phase extraction, capillary GC, and mass selective detection have been used to determine 3‐carboxy‐4‐methyl‐5‐propyl‐2‐furanpropionic acid (furanpropionic acid) and hippuric acid in the plasma of patients with chronic renal failure. The concentrations of furanpropionic acid and hippuric acid were found to be highly elevated and reached levels of 4.56 ± 2.37 mg/dl (10 to 20‐fold higher than normal) and 12.90 ± 14.06 mg/dl (40 to 60‐fold), respectively. Treatment by hemodialysis and hemofiltration effectively eliminated hippuric acid (on average by 66 and 56%, respectively) but had little effect on furanpropionic acid. Intermittent peritoneal dialysis gave the best long‐term results. Both components were maintained at a lower level than by hemodialysis and hemofiltration.
Optimization of GC detector parameters using electronic pressure control
Authors: Klein Kenneth J. , Larson Paul A. , Breckenridge Jill A. 
Published: May 2005

AbstractHP 5890 Series II Gas Chromatographs are equipped with prototype hardware enabling electronic pressure programming of all detector and carrier gases. A method of using electronic pressure control (EPC) to optimize detector performance (sensitivity, selectivity, and baseline stability) is demonstrated. With EPC, sample introduction, column separation, and detector performance can be optimized simultaneously without the classical trade‐offs in performance. An example is also presented of the use of a new automated system which enables cool on‐column injection into 250 or 320 μm columns without the need for a retention gap.
High‐speed narrow‐bore capillary gas chromatography in combination with a fast double‐focusing mass spectrometer
Authors: Van Ysacker Peter G. , Brown Jeff , Janssen Hans‐Gerd , Leclercq Piet A. , Phillips Andy 
Published: May 2005

AbstractIn this work the application of high‐speed narrow‐bore capillary GC in combination with a fast scanning double focusing magnetic sector mass spectrometer is evaluated. Special emphasis is placed upon detection limits and scan speed in the full scan mode and in the selected ion monitoring mode (SIM). In the full scan mode, up to 20 scans per second could be obtained. The detection limits are in the low picogram range in the full scan mode and improve even to 5 to 50 fg in the SIM mode, depending on the sample complexity and mass resolving power. It will be illustrated that by increasing the resolution in the SIM mode, interferences from ions of the same nominal mass‐to‐charge ratio as the ions of interest are significantly reduced. Chemical background noise can therefore be largely eliminated, thus enhancing the signal‐to‐noise ratio.
High temperature vaporizing chambers for large volume GC injections and on‐line LC‐GC
Authors: Boderius Ulf , Grob Konrad , Biedermann Maurus 
Published: May 2005

AbstractThe suitability of some chambers for sample evaporation at high input flow rates (>100 μl/min) was studied by visual experiments. The chambers were at temperatures far above the solvent boiling point in order to achieve the heat transfer required. Shooting liquid owing to violent evaporation, flooding of the chamber as a result of cooling, and excessively high vapor pressure causing backflow into the gas supply system were found to be the limiting factors. Fused silica capillaries into which a piece of wire or polyimide‐free fused silica capillary had been inserted were found to be suitable for the vaporization of “easy” solvents, such as alkanes (up to some 1.7 ml/min), but packed beds were required to achieve favorable evaporation of dichloromethane or methanol/water (up to some 800 and 300 μl/min, respectively).
Capillary electrophoresis in allergen preparation research and in production control
Authors: Pacáková V. , Pechancová J. , Štulík K. 
Published: May 2005

AbstractA CE method has been developed for the analysis of wasp venoms and pollen extracts of Phleum pratense and Betula verrucosa. Various electrolyte systems can be used but the best separation and reproducibility are attained in 0.15 mol/l phosphoric acid, pH 1.8. UV photometric detection at 190 nm is sufficiently sensitive for determination of the polypeptides and glycoproteins contained in these materials (the detection limit for phospholipase A2 is 0.4 ng). The allergens from wasp venoms and pollen extracts yield characteristic electropherograms which can be used for control of the allergen production. Modification of capillary wall with poly(ethylhydroxy methacrylate) causes a decrease in the migration times and the separation efficiency is retained.
Strand orientation of [α]‐oligodeoxynucleotides in triple helix structures: Dependence on nucleotide sequence
Authors: Sun Jian‐sheng , Lavery Richard 
Published: May 2005

AbstractThe aims of the present theoretical study of the conformations of [α]‐oligodeoxynucleotides forming triple helices with DNA duplexes are to understand the structural and energetic factors involved in [α]‐triple helix formation by means of energy minimization, and to explain the experimentally observed dependence of strand orientation on the nucleotide sequence. It is found that the energetically preferred orientation of the [α]‐oligonucleotide with respect to the homopurine strand depends on the sequence of the homopurine. homopyrimidine tracts. This is a consequence of the structural heteromorphism of base triplets in the intrinsically more stable reverse Hoogsteen hydrogen bonding configuration. Practical rules are proposed for determining the orientation of the nuclease‐resistant [α]‐oligodeoxynucleotide strand which will form the most stable triple helix.
Raman band contours. II: Symmetric top molecules
Authors: Masri Frederick N. , Fletcher William H. 
Published: May 2005

AbstractThe general theory of Raman band contours of symmetric tops is discussed briefly, and a program for the calculation of the band contours for the degenerate bands of prolate and oblate symmetric tops is described. The band contours as a function of the Coriolis coupling constant, zeta, have been computed for the range ζ = −1.0 to + 1.0 and for values of beta (A/B–1) ranging from −0.5 (planar oblate top) to + 3.0. The results, which are presented in tabular and graphical form, can be used to determine approximate values of zeta from the contours of unresolved bands for molecules in which the selection rules are restricted to ΔK = ± 1 or ΔK = ± 2. Limitations and sources of error are discussed.
Lattice Raman spectrum of pyridine‐N‐oxide
Authors: Pujari P. R. , Bist H. D. 
Published: May 2005

AbstractStokes and anti‐Stokes components in the lattice vibrational laser excited Raman spectrum of a polycrystalline sample of pyridine‐N‐oxide are reported. The six prominent peaks at 108, 80, 71, 49, 36 and 20 cm−1 have been tentatively assigned to librational and translational lattice oscillations of the molecule.
The effect of the internal field on Raman scattering cross sections
Authors: Nestor James R. , Lippincott Ellis R. 
Published: May 2005

AbstractThe increase in amplitude of incident and Raman scattered radiation brought about by the dielectric nature of liquids is known as the internal field effect and is responsible for increasing scattering cross section with increasing refractive index. This effect has been investigated quantitatively by independent measurements of corresponding liquid and gas phase cross sections of 53 Raman bands, or groups of bands, from 14 different organic compounds. Agreement with proposed theory is obtained in most cases, notable exceptions occurring with hydrogen bonded liquids.
Method for the measurement of absolute Raman scattering cross sections of crystalline powders
Authors: D'orazio M. , Schrader B. 
Published: May 2005

AbstractThe theory of the Raman intensity of crystal powders given by Schrader and Bergmann [8] describes the radiation balance of a turbid medium by a scattering module r, an absorption module a and a Raman scattering module s. On the base of this theory the necessary experimental conditions and the evaluation procedure for the determination of absolute Raman scattering cross sections are given.
Raman spectroscopy at electrode‐electrolyte interfaces
Authors: Fleischmann M. , Hendra P. J. , McQuillan A. J. , Paul R. L. , Reid E. S. 
Published: May 2005

AbstractThe nature of various electrode‐electrolyte interfaces have been investigated using vibrational Raman spectroscopy. This novel application of Raman spectroscopy has provided previously inaccessible structural evidence on the environment close to the electrode surface.
High resolution Raman spectroscopy of gases with laser sources. IX. The rotational spectra of cycloheptane and cyclooctane
Authors: Kainnady Jacob V. , Weber Alfons 
Published: May 2005

AbstractThe pure rotational Raman spectra of cycloheptane (C7H14) and cyclooctane (C8H16) vapor were photographed using a high resolution plane grating spectrograph. Both spectra resemble those of symmetric top rotors. The spectrum of cycloheptane has well developed R‐ and S‐branches while for cyclooctane the R‐branch lines are only just observable. The molecular constants obtained for these two molecules are for cycloheptane: B =0.099 3801±0.000 0047 cm−1 and DJ =(4.08± ±0.17) × 10−8 cm−1 while for cyclooctane: B0.073 221±0.000 039 cm−1 and DJ =(0.784±0.039) × 10−8 cm−1 where the quoted errors are one standard deviation. Since both molecules exist at room temperature in several conformations these constants are average values over the various conformers.
Determination of A0 for CH3D from the ν4 Raman band
Authors: Kattenberg H. W. , Brodersen Svend 
Published: May 2005

AbstractThe ν1 Raman band of CH3D has been analysed by means of ground state combination differences. The results are in good agreement with those obtained by Olson from perturbationallowed infrared transitions. The present work removes a previous discrepancy between infrared and Raman results, and shows that the Raman method may yield A0 values with low systematic errors.
Liaison hydrogène en phase liquide et spectrométrie Raman. III—structure et intensité de la bande ν(OH) d'alcools primaires en solvants inertes
Authors: Perchard C. , Perchard J. P. 
Published: May 2005

AbstractThe Raman spectra of methanol in CCl4 solutions and of isopropanol in freon mixtures were recorded in the OH(OD) stretching region for different concentrations and temperatures. As for pure liquids one observes in the high polymer region a two‐component structure which is shown to originate from intermolecular coupling. Measurements of the scattering activity of the ν(OH) and ν(CH) bands for increasing concentrations shows the invariance of the Raman intensity for the ν(CH) bands but an increase for the ν(OH) band.
Raman spectrum of the ν3 band of ethylene‐H4
Authors: Ohashi N. , Kyogoku T. , Matsuoka S. 
Published: May 2005

AbstractThe Raman‐active ν3 band of ethylene‐H4 measured with a resolution of about 0.5 cm−1 was analysed by using the computing program prepared for the analysis of Raman spectrum under low or medium resolution. Results close to those of Foster et al. were obtained from this analysis.
Analyse Vibrationnelle de la thiazolidine
Authors: Guiliano M. , Mille G. , Avignon T. , Chouteau J. 
Published: May 2005

AbstractUn champ de forces de valence a été défini pour la thiazolidine et cinq dérivés deutériés. Les résultats expérimentaux (IR, Raman) et théoriques (calcul des modes normaux) ont permis de proposer pour l'ensemble des composés une attribution complète des divers modes de vibration en précisant la nature de chacun d'eux.