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  • Gas chromatography  (54)
  • Springer  (54)
  • Cell Press
  • 2005-2009
  • 1985-1989  (39)
  • 1980-1984  (15)
  • 1988  (39)
  • 1980  (15)
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  • 2005-2009
  • 1985-1989  (39)
  • 1980-1984  (15)
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  • 1
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Simultaneous distillation-extraction ; Cheese volatiles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A simultaneous distillation-extraction apparatus proposed by Godefroot has been used for the GC study of volatile components of cheese. 5–10 g of cheese provide a fraction that can be directly injected into a GC or a GC/MS. Two capillary columns (SE-30 and SP-1000) were evaluated, the second one being adequate for quantitative determinations. Camphor was used as internal standard. The coefficients of variation ranged from 1.4 to 11.8. The technique can be used as a fast method for the characterization of cheeses from their volatile component concentrations.
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  • 2
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    Chromatographia 25 (1988), S. 1087-1088 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Log plot ; Homologous series
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The slope of the log plot of the adjusted retention time of a homologous series usually varies from that of the n-alkane series by no more than 2%, though with unusual interactions between the functional group and the stationary phase the difference may be as high as 7%.
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  • 3
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Preparative scale separations ; Plate model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Two close-boiling materials, diethyl ether (DEE) and dichloromethane (DCM), were separated to investigate the effects of the pure components and the mixture on elution in preparative gas-liquid chromatography. Nitrogen was used as the carrier gas, and the chromatographic column (1 cm I.D. and 0.75m length) was packed with Chromosorb A with different quantities of dinonyl phthalate stationary phase and particle sizes. Below ca. 7% (by wt.) of feed concentration, the experimental elution curves of pure DEE and DCM were almost the same as those of the mixture, and the theoretical plate model can be used successfully to predict the elution curves.
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  • 4
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    Chromatographia 25 (1988), S. 404-408 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Silica surface modification ; Hexamethylcyclotrisilazane ; Hexamethyldisilazane ; Support materials
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The paper is concerned with the structure of an organic layer bonded to the silica surface modified with silazanes. The changes of the retention volumes of hydrocarbons is studied for the silicas modified with hexamethylcyclotrisilazane, hexamethyldisilazane and their mixtures. It is shown that most of the carbon in the layer after hexamethylcyclotrisilazane modification is bonded to the surface by Si−O−Si bonds. This fact supports the assumption of a fragmentation of the cyclosilane used for modification.
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  • 5
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Statistical criteria ; Non-linear models ; Constants for n-alkane retention curve ; Multiparametric least-squares adjustment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Multiparametric, least-squares, regression treatment of G.C. data is extended to describe deviations from the usual linear model. Through statistical evaluation of results, four parameters models are generally found adequate and the use of higher degree empirical models is discouraged.
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  • 6
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    Chromatographia 25 (1988), S. 539-542 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Temperature programming ; Retention index
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A method is presented for the calculation of retention indices at an assigned temperature from temperature-programmed data. If the retention times at two different program rates for the solutes and the n-alkanes are known, the retention indices at an assigned temperature can be calculated directly.
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  • 7
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    Chromatographia 26 (1988), S. 125-132 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Non-equilibrium frontal chromatography ; Nonlinear isotherms ; Variable velocity ; Multicomponent mixtures
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The paper presents a classification of various theoretical models for multicomponent gas chromatography at u=var for high concentrations of the mixture components with consideration of the major distinctive features of the interphase mass exchange inside the porous grains of the adsorbent and outside them within the porous medium of the chromatographic column. It has been shown that the conditions determining a given front behaviour of multicomponent gas mixture at u=var depend on: theoretical models for the kinetics and dynamics of adsorption; the values of mass exchange parameters inside the porous grains and in the porous medium. Formulae have been derived for calculating the values of the quantities characterising the frontal behaviour in the stage of adsorption and desorption of multicomponent mixture at u=var.
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  • 8
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    Chromatographia 25 (1988), S. 21-24 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Sample concentration ; Chromatographic evaporation ; Solvent effect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Several micro-techniques for the removal of solvent from dilute solutions of volatile compounds have been compared. Large solute losses were experienced when the conventional blow-down technique was applied. Better yields could be obtained with static evaporation procedures, as long as an effective reflux was maintained. However, careful optimization of the vessel design and operating conditions is necessary. The most efficient volume reduction technique was shown to be chromatographic evaporation. Quantitative recoveries were obtained for the compounds tested and the process was significantly faster than static concentration. Moreover, operating conditions (gas flow, temperature) are less critical. With modifications, the principle can be used for the concentration of large sample volumes down to a few microliters.
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  • 9
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Stationary phase polarity ; Polarity parameters ; Structure-retention relationships
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The new stationary phase polarity parameters BN and BS evaluated from the concept of the electric intermolecular interactions are used to describe the polarity of polyoxyethylene glycol dialkyl ethers and their sulphur analogs. Relations between the discussed parameters and accepted measures of surfactants' polarity are presented and discussed. The considered parameters are correlated with the compound structures. Structural increments for characteristic fragments of the molecule are calculated and use to predict BN and BS values.
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  • 10
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    Chromatographia 25 (1988), S. 134-138 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Sulfur ; n-Octane adsorption
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary From the adsorption isotherms of n-octane on the surface of sulfur at 29.8°C and 40.6°C some thermodynamic functions were determined. On the basis of these data the structure of the adsorbed layer of n-octane is postulated. The molecular interactions and adsorption mechanism are also discussed. It is stated that both quasi-liquid and quasi-sold layers may be formed on the surface of sulfur depending on the surface coverage with n-octane.
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  • 11
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    Chromatographia 25 (1988), S. 313-318 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Retention index ; Slope of log plot ; Homologous series ; Partition coefficient
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The slope of the n-alkane log plot dt′R/dnc (t′R=adjusted retention time; nc=carbon number) for a stationary phase can be used to obtain the retention index of an unidentified substance in a chromatogram containing only one peak with a known retention index, or to predict the retention time of a substance from that of a different homolog in the same series. It can also be used to translate retention indices into relative retention time, partition coefficient or specific retention volume. Published values of the slope are collected and critically evaluated. Equations are deduced that predict its approximate value at a specified temperature given the value at only one other temperature.
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  • 12
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    Chromatographia 25 (1988), S. 393-396 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Separation of optical isomers ; Chirasil-Val capillary columns ; Amino acid esters
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary D,L-amino acids were derivatized with (+), (±)-2-butanol or N-trifluoroacetyl-L-prolyl chloride (L-TPC) and then chromatographed. Four optical isomers were separated on a Chirasil-Val capillary column. By this method, the concentration of optical impurities arising from the commercial optically active reagents can be determined. The observed abnormal elution orders of enantiomeric amino acid esters may be caused by a selective intermolecular force.
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  • 13
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Essential oils ; Evaporation rate ; Perfume composition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A simple method was developed for the determination of the evaporation rate of essential oils and perfumery composition using gas chromatography with temperature programming. The volatility of 19 essential oils and 17 perfumery composition was evaluated. The method is useful for different comparative measurements.
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  • 14
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    Chromatographia 25 (1988), S. 598-602 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Capillary columns ; Steroid profiles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Steroid conjugates are hydrolysed enzymatically using β-glucuronidase after extraction from urine using a solid phase extraction cartridge. After hydrolysis the free steroids are removed from the matrix, again utilising solid phase extraction. Derivatisation of the free hydroxyl groups using Hydrox-Sil AQ produces the respective TMS ethers which are extracted into hexane, in which solvent they are stable for many days. Capillary GC analysis with flame ionisation detection produces a profile of the steroids present in the sample. This technique is suitable for following changes in the urinary excretion profiles of patients undergoing investigation for a variety of steroid production-related diseases.
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  • 15
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    Chromatographia 25 (1988), S. 609-612 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Gas chromatography ; Triglyceride composition of grapes ; Identification system
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The triglyceride composition of the Tempranillo grape (Vitis vinifera) has been examined by a combination of HPLC and GLC. To identify the triglycerides, equations were applied relating log k′ with the molecular variables: equivalent carbon number, chain length and number of double bonds in each of the fatty acids in the glycerides. Ten triglycerides were found, the principal ones being trilinolein (35.75%), dilinoleyl-olein (21.03%) and dilinoleyl-palmitin (17.02%).
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  • 16
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    Chromatographia 25 (1988), S. 655-658 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Structure-retention relationships ; Connectivity indices, topological indices ; Alkenes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Retention indices of different alkenes are correlated with connectivity and topological parameters. The appropriate statistically valid relations hips are derived and discussed.
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  • 17
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    Chromatographia 25 (1988), S. 735-736 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; α,ω-diiodoperfluoroalkanes ; Separation ; identification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The separation of α,ω-diiodoperfluoralkanes on a glass capillary column coated with OV-101 methylsilicone was investigated. Retention indices were determined at three temperatures (140, 150 and 160°C). The correlation between the retention indices and the boiling points of the investigated compounds was studied.
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  • 18
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    Chromatographia 25 (1988), S. 731-734 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Retention Index (l) ; Temperature dependence of Retention Index
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A linear dependence of (T−T1)/[1(T)−1(T1)] on temperature (considering the retention index 1(T1) at temperature T1 as a standard value) is derived. Both ther retention index at an assigned temperature and the temperature dependence of the retention index can be calculated from retention data measured at two temperature-programing rates.
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  • 19
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    Chromatographia 26 (1988), S. 171-177 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; GC/MS analysis ; Polycyclic aromatic hydrocarbons ; Bituminous coal ; Brown coal ; Plant waxes ; Thermodesorption
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Polycyclic aromatic hydrocarbons (PAH) today are ubiquitous detectable constituents of recent sediments. The compounds are adsorbed on particulate emissions and are thus transferred to the environment. To date the analysis of PAH in sediments, dust samples and plant material is based mainly on the application of solvent-extraction methods followed by liquid chromatography and/or gas chromatographic separation of the extracts. An alternative approach for the analysis of PAH in solid samples such as coal, sediments, dust samples and plant waxes is shown in this contribution. A commercially available device for the analysis of volatile compounds present in solid matter is connected on-line to a GC/MS system. The device enables the thermal desorption of hydrocarbons at a temperature of 320°C. Subsequently, the hydrocarbons trapped on the initial part of the capillary column are analyzed by GC/MS. The application of mass chromatography provides the possibility of detection and quantitation of PAH in complex mixtures even when they coelute with other compounds. The sample amount required varies between 1 and 10 mg depending on the hydrocarbon content.
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  • 20
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    Chromatographia 26 (1988), S. 229-233 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Glass capillaries ; Chirasil-Val ; Immobilisation ; Enantiomeric separation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Immobilisation methods of the chiral silicone stationary phase Chirasil-L-Val have been studied. In addition to the standard techniques of radical-induced immobilisation with dicumyl peroxide and azo tert-butane, immobilisation was solely achieved by thermal treatment: conditioning at low flow-rates or under stop-flow conditions led to unexpectedly high immobilisation despite mild temperatures. The presence of water vapor in the carrier gas accelerated the immobilisation process. While up to 75% immobilisation was attainable with both ATB and thermal methods, immobilisation with DCUP did not exceed 50%, despite relatively high DCUP concentrations. Whilst all immobilisation methods were accompanied by varying degrees of racemisation at the chiral centre, it was possible to establish conditions that yielded a high immobilisation (in excess of 70%) with a negligible loss in enantiomeric selctivity. The immobilisation reactions also slightly affected the polarity of the stationary phase, reflected in a shift of the Kovats-Indices of amino acid derivatives and in the accompanying “Squalane-Effect”. With respect to immobilisation, racemisation and polarity shift, thermal immobilisation with water-saturated carrier gas proved to be the optimum method.
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  • 21
    ISSN: 1612-1112
    Keywords: Gas chromatography ; (S)-(+)-Naproxen ; Amino acid methyl esters ; Resolution of diasteroisomers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A GC method has been elaborated for the separation of enantiomers of some amino acid methyl esters after derivatization with activated (S)-(+)-naproxen. Nine amino acid ester paris were completely resolvede in a single run on a fused silica capillary column.
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  • 22
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    Chromatographia 25 (1988), S. 993-998 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; HPLC system ; Micropacked column ; Organic mobile phase ; UV detection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Retention behaviours of aromatic hydrocarbons were examined by using the vapour of an organic substance as the mobile phase and silica gel as the stationary phase. Gas chromatographic separation of aromatic hydrocarbons was demonstrated by using a system comprising a liquid chromatographic (LC) pump, a micropacked column for LC, a column oven and a UV detector.
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  • 23
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Retention index ; Hydrocarbons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The retention of hydrocarbons present in the C5 pyrolysis fraction of gasolines on the stationary phases squalane and methylsilicone oil JXR at 30, 40 and 50°C was investigated by capillary gas chromatography. The unified retention indices of the hydrocarbons were also calculated on squalane. The retention indices obtained on these two phases were interrelated and the quantitative relationship with the structure of the solutes was studied. Equations based on the unified retention indices calculated on squalane and some selected structural elements of the solutes permit the calculation of their retention on methylsilicone with sufficient accuracy.
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  • 24
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    Chromatographia 25 (1988), S. 589-592 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Hold-up time determination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary New versions are suggested for the gas hold-up time calculation in gas chromatography. The results are compared with those obtained by using other methods. The advantages of the suggested ways of calculation are pointed out.
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  • 25
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    Chromatographia 25 (1988), S. 621-626 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Pre-column photolysis ; Halogenated hydrocarbons ; Identification of photolysis products ; Reaction mechanisms
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Photodecomposition of chloro- and bromoderivatives of saturated, unsaturated and aromatic hydrocarbons has been studied under flow conditions using reaction gas chromatography. The photodegradation products were separated on a column coated with squalane and identified by comparing the measured retention data with those of standards and published retention indices, The results can be used to clarify the decomposition of such compounds.
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  • 26
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    Chromatographia 25 (1988), S. 725-730 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Structure-retention correlation ; Kováts retention index ; Alkylaromatics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Relative retention data and Kováts retention indices were measured for several hydrocarbons (mainly for alkylbenzenes) on dinonylphtalate and polyethylenelycol 4000 stationary phase. Correlations were searched between these retention data and the following physical (boiling point, molrefraction, molvolume) and topological (connectiviity index and general index of molecular complexity) properties of solutes. The best fitting equations was choosen among more than 150 equations involving linear, quadratic, exponential, two variables linear and quadratic dependence of retention data and the properties mentioned as well as their inverses.
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  • 27
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    Chromatographia 25 (1988), S. 817-821 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Water analysis ; Macroreticular polymeric adsorbent resins ; Herbicides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A method is described for the determination of 3-phenyl-4-hydroxy-6-chloropyridazine in potable water. The method is based on isolation and enrichment by passing the water sample through a column of macroreticular polymeric adsorbent resin, concentration, derivatisation with pentafluorobenzoyl chloride and GC measurement with a N-specific detector. The individual experiments for establishing the working conditions, especially the adsorption characteristics of different types of resin, are described. The highest enrichment efficiency is obtained with the methacrylate-type resin XAD7. In field-sampling experiments a 10cm column yields 57% recovery at 100mLmin−1 flow rate, 0.3 ppb concentration level and 1 L sample volume. The method is completely documented; performance data are a detection limit of 0.07 μg L−1 and a mean recovery of 75% at the 0.3 ppb level.
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  • 28
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Liquid crystals ; Thermodynamic properties
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Thermodynamic properties of 22 solutes at infinite dilution have been determined in the smectic, nematic and isotropic mesophases of 4,4′-bis(heptyloxy)azoxybenzone. The thermodynamic properties are discussed in relation to the solute-solvent (liquid crystal) interactions as conditioned by the degree of order in the liquid crystal.
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  • 29
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Perhalogenated compounds ; Relative retentions ; Identification by interpolation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Separation of perhalogenated compounds resulting from thermolysis, photolysis or radiolysis of mixtures of halogens in carbon tetrachloride was carried out by programmed temperature gas chromatography. Plots of relative retentions (to CBr4) vs the number of bromine atoms present for known compounds of the general formula CxBryClz (x=1 and 2; y+z=4 or 6) gave three linear correlations (all with r〉0.99). These correlations permitted projections of the identities of reaction products for which no standards were available. These projections were later confirmed by CG-MS. *** DIRECT SUPPORT *** A0732166 00010
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  • 30
    ISSN: 1612-1112
    Keywords: Gas chromatography ; On-line process analysis ; Injection of volatile compounds
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A modified on-line liquid injection technique with rotary valves for gas chromatography has been developed. Applications for the on-line analysis of 2-methylpropene, cyclohexene and 1-butene are described. All samples were loaded under pressure. The results obtained show excellent reproducibility with less than 0.1% relative standard deviation (r.s.d.; n=6) for the peak areas measured. The method is particularly advantageous for samples containing both gas and liquid ccomponents at one bar.
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  • 31
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    Chromatographia 25 (1988), S. 87-90 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Free acids in cheese ; Tetramethylammonium hydroxide soaps ; Packed and capillary columns
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A rapid gas chromatographic method for the analysis of individual free fatty acids (FFA) in cheese has been developed. Lipds were extract from a cheese paste acidified with diethyl ether and tetramethylammonium hydroxide (TMAM) was used for converting the FFA to TMA-soaps, which are transformed to methyl esters in the chromatographic injector. The effect of lactic acid was determined. The reproducibility of the method was studied and the coefficient of variation for the total FFA was found to be 2.2%. Recovery of individual FFA was in the range 87 to 106%.
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  • 32
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    Chromatographia 25 (1988), S. 453-454 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Reversed-flow technique ; Polymer activities ; Polymer interaction parameters
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The reversed-flow, gas-chromatographic method for measuring activities and activity coefficients in binary liquid mixtures is now extended to the determination of activity coefficients of the solvent in polymer-solvent systems over the whole range of polymer concentration, as well as for the calculation of Flory-Huggins interaction parameters. The parameters found by the present method are compared with those determined by other techniques or calculated theoretically.
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  • 33
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Glass capillary columns ; Bile acids ; Hexafluoroisopropyl esters
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A modified gas chromatographic glass capillary technique for determination of five major bile acids (Cholic acid: CA, Chenodeoxycholic acid: CDCA, Deoxycholic acid: DCA, Lithocholic acid: LCA and Ursodeoxycholic acid: UDCA) has been developed after preliminary extraction with XAD-2 resin. Enzymatic hydrolysis prevents the formation of interferring degradation products. Ether extraction with centrifugation eliminates water soluble interferring substances. Derivatization to hexafluorpropyl- instead of methyl esters results in better separation, shortens analysis time and prolongs the life span of the column.
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  • 34
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    Chromatographia 25 (1988), S. 547-559 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Liquid column chromatography ; Process scale separations ; Review
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The relative merits of large scale gas chromatography (GC) and high performance liquid chromatography (HPLC) have not been reviewed for some considerable time. Although methodologies capable of manufacturing high efficiency (and hence cost effective) plant have existed for over a decade, commercial introduction has been remarkably slow. This has primarily been caused by confidentiality restrictions placed on equipment manufacturers, in turn severely limiting wide ranging applications data. These are necessary to raise potential end users confidence that both techniques offer viable large scale routes to separation and purification of mixtures as analysed by laboratory chromatographic methods. Considerable recent progress has been made with large scale HPLC plant, which has led to sufficient published data to make both technical and economic comparisons against GC possible.
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  • 35
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    Chromatographia 25 (1988), S. 618-620 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Toluenesulfonic acid isomer distribution ; Ethyl toluenesulfonate isomers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A gas chromatographic method for the determination of isomeric distribution in toluenesulfonic acid samples is described. The acids are transformed into the corresponding ethyl esters by reaction with triethyl orthoformate in toluene. The reaction mixture can be injected, without further purification, into the gas chromatograph. The separation is best performed on columns containing OV-210 or polyphenyl ether (6 rings) as the stationary phase.
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  • 36
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    Chromatographia 25 (1988), S. 691-693 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Al, Cr, Co and Fe acetylacetonates ; Capillary column separation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The retention and resolution of simple mixture of Al(III), Cr(III), Co(III), and Fe(III) acetylacetonates were investigated on capillary columns coated with methyl and methyl phenyl silicones (OV-1 or OV-17) used as the stationary phase, at different column temperatures and carrier gas flow rates. Successful elution and good resolution were obtained only for the Al(III) and Cr(III) complexes, both under isothermal and programmed-temperature conditions; better resolution was observed on the column coated with OV 17.
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  • 37
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    Chromatographia 26 (1988), S. 300-304 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Column liquid chromatography ; Polycyclic aromatic hydrocarbons ; Phenolic compounds ; Air pollution
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    Topics: Chemistry and Pharmacology
    Notes: Summary An improved procedure for the determination of the less volatile air pollutants of recycled closed atmospheres by activated carbon-Soxhlet extraction is proposed. After total treatment of desorbate, PAH determination is then accomplished by RP-HPLC using both adsorptiometric and fluorimetric UV detection; phenolic compounds are determined by GC-MS. This technique is suitable for very low levels of PAH and phenolic compounds.
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  • 38
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    Chromatographia 26 (1988), S. 34-36 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Gas analysis in halogen lamps ; Sampling device
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    Topics: Chemistry and Pharmacology
    Notes: Summary A new type of gas sampling device was constructed to improve the analysis of the gas in halogen lamps. Low levels of gases such as O2, CH4, C2H4 and CH3Br could be determined by the techniques worked out.
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  • 39
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    Chromatographia 26 (1988), S. 413-416 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Gas analysis in incandescent lamps ; Gas chromatographic determination of O2 impurity in argon
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A sensitive GC method was developed to analyse O2 (∼10–400ppm) in argon, by using Ar as carrier gas. A sampling method was developed for lamp analysis, and the O2 impurity content in the gas filling of incandescent lamps was measured. The results of the GC and MS measurements were in good agreement.
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  • 40
    ISSN: 1432-0878
    Keywords: Preputial glands ; Nude mice ; Ultrastructure ; Gas chromatography
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    Topics: Biology , Medicine
    Notes: Summary The preputial glands of male nude (nu/nu) mice were analyzed by a combination of electron microscopy and gas chromatography to determine whether or not they are affected, like developing hairs and nails, by the nu/nu genotype. Results of the analyses revealed no differences between the glands of nude and normal male mice in either their ultrastructural characteristics or lipid secretory products.
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  • 41
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    Chromatographia 13 (1980), S. 203-206 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Carrier gas purity ; Sample stability
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    Topics: Chemistry and Pharmacology
    Notes: Summary The amount of oxygen which may be present in the gas volume corresponding to a peak is investigated and compared to the sample amounts. It is shown that even with high purity carrier gases one may have a significant excess of oxygen present at low sample amounts. Attention is drawn to the possibility of impurity build-up by diffusion e.g. through the septum.
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  • 42
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    Chromatographia 13 (1980), S. 263-270 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Metal complexes ; Enantiomers ; Isotopic composition
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    Topics: Chemistry and Pharmacology
    Notes: Summary The high selectivity of complexation gas chromatography has been employed for enantiomer resolution and isotope separation. Thus, a chiral olefin, 3-methylcyclopentene, has been resolved analytically on optically active dicarbonyl-rhodium(I)-3-trifluoroacetyl-1R-camphorate in squalane. The deuterated ethylenes C2H4−nDn have been separated on the same rhodium(I)-containing stationary phase. The chiral aliphatic oxiranes epoxypropane andtrans-2,3-epoxybutane have been resolved on optically active nickel(II)-bis-3-trifluoroacetyl-1R-camphorate in squalane.
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  • 43
    ISSN: 1612-1112
    Keywords: Gas chromatography ; On-column abstraction ; Aliphatic aldehydes ; Amine antioxidants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The selective on-column abstraction of aliphatic aldehydes by gas chromatographic stationary phases containing N-iso-propyl N′-phenyl-p-phenylenediamine is described.
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  • 44
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    Chromatographia 13 (1980), S. 35-39 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Nitromethane ; Nitroalkanes
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    Topics: Chemistry and Pharmacology
    Notes: Summary Impurities in commercially available nitromethane have been determined by gas-liquid chromatography using six different column packings. Besides nitromethane, 1-nitropropane, 2-nitropropane, acetonitrile, methanol, small amounts of ethanol and acetaldehyde have been detected. The presence of formaldehyde, ethyl acetate and acetone is probable. Mixtures containing comparable amounts of the four nitroalkanes could be separated on all columns, but plots of logarithms of the retention times vs. carbon number or boiling points of the nitroalkanes or column temperatures were linear only in case of columns packed with Porapak R and Q.
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  • 45
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    Chromatographia 13 (1980), S. 686-692 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Micropacked columns in GC ; Microparticles
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    Topics: Chemistry and Pharmacology
    Notes: Summary Porous silica microparticles designed for modern liquid chromatography have proven effective in gas chromatography. Columns of 35–50 cm gave plate heights as low as 3.3 particle diameters and speeds of 2400 theoretical plates per second or 500 effective theoretical plates per second. Inlet pressures up to 70 atmospheres were required using hydrogen as carrier gas. The particles as received were too retentive for fast chromatography and gave asymmetric peaks. A coating of fluorosilicone oil overcame both problems. Other coatings were less effective. Bonded phases proved less satisfactory on both counts and also gave substantially less efficient columns and greater flow resistance. Column efficiency and flow resistance were sharply dependent on physical properties of the particles. The most efficient packing was clearly spherical particles of 5–10 μm diameter with narrow size distribution, pore diamters about 50 nm, BET surface areas of 25–50 m2/g and surfaces modified with trifluoropropyl silicone. A six-component hydrocarbon sample was separated in 33 s with a resolution of 4 for the most difficult pair and in 2.6 s with a minimal resolution. Performance was limited by end effects and by available pressure so that much better performance can be expected from longer columns and higher pressures.
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  • 46
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    Chromatographia 13 (1980), S. 752-754 
    ISSN: 1612-1112
    Keywords: Xylenol isomers ; Gas chromatography ; Polyols and polyethers as stationary phase ; Hydrogen bonding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Xylenol isomers can be resolved on most polyols (sugars or sugar alcohols) and polyethers (polyethylene glycol or polypropylene glycol) with hydrogen-bonding interaction. They are separated on vinical polyols which have more hydroxy hydrogen than tetrol, and even on vicinal triol when its hydroxy hydrogen is acidic (stronger proton donor). The stronger is the hydrogen bonding interaction between xylenols and the liquid phase, the better is the separation of 2,4- and 2,5-xylenol, and the poorer the separation of 2,4-and 2,3-xylenol.
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  • 47
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    Chromatographia 13 (1980), S. 651-660 
    ISSN: 1612-1112
    Keywords: Capillary columns, glass ; Gas chromatography ; Column preparation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Glass capillary column chromatography is the most rapidly growing part of gas chromatography. There are many complex new analytical tasks and they require special capillary columns. Fortunately there is a wide range of column preparation methods available, and they make the preparation of glass capillary columns a more varied job than that of packed columns. In this paper these methods are reviewed and suggestions are given for making task-oriented columns.
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  • 48
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    Chromatographia 13 (1980), S. 73-84 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Gas hold-up time ; Dead time
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    Topics: Chemistry and Pharmacology
    Notes: Summary The two approaches used for the calculation of the gas hold-up time and thus, the adjusted retention time are outlined, first for the restricted case when the carbon numbers of the three homologues used for the calculation are evenly spaced (c3−c2=c2−c1) and then, for the general case when (c3−c2) differs from (c2−c1). The basic difference in the philosophy of the two approaches is shown.
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  • 49
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Column characterization ; Oxidation ; Stationary phases
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The on-column oxidation of hydrocarbons commonly used as stationary phases in column characterization is investigated. In each case significant shifts of retention are observed, which may be negative or positive depending upon the polarity of the test solutes and the adsorptivity of the support material. In order to reduce the consequent uncertainties in the Rohrschneider [1] and McReynolds [2] polarity values, a new method of column characterization is proposed. The applicability of the new method is illustrated by a consideration of a range of silicone liquid phases.
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  • 50
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    Chromatographia 13 (1980), S. 207-208 
    ISSN: 1612-1112
    Keywords: Trace determination ; Hydrogen chloride ; Ethylene oxide ; Gas chromatography ; Chlorinated solvents
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A method is described for the determination of small quantities of hydrochloric acid in two chlorinated organic solvents (CHCl3 and CCl4). An excess of gaseous ethylene oxide is added to a liquid sample; the 2-chloroethanol formed is then analyzed by gas chromatography. The procedure is simpler and more sensitive in comparison with other conventional methods. It can be modified for other organic solvents.
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  • 51
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    Chromatographia 13 (1980), S. 567-571 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Helium detector
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    Topics: Chemistry and Pharmacology
    Notes: Summary Four main factors which determine the shape and the polarity of the helium detector signal are discussed. All possible responses of this detector, both in elution and in vacancy chromatography, are presented and special attention is drawn to the intermediate region. The idea of ionization vacancy is introduced for the specific case of two components which are unresolved by the column and to which the detector responds with different sensitivity.
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  • 52
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    Chromatographia 13 (1980), S. 574-575 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Xylenol isomers ; Sugar derivatives as liquid phases
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Adenosine, guanosine and inosine used as liquid phases in gas chromatography permits the separation of all six xylenol isomers.
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  • 53
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    Chromatographia 13 (1980), S. 61-67 
    ISSN: 1612-1112
    Keywords: Optimization ; Carrier gas velocity ; Gas chromatography ; Influence of temperature on optimum velocity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Zusammenfassung Die Wahl der mittleren, linearen Trägergasgeschwindigkeit bei der Analyse von Mehrkomponentengemischen unter isothermen und temperaturprogrammierten Bedingungen wird diskutiert. Es wird gezeigt, daß stets eine Trägergasgeschwindigkeit gewählt werden sollte, die mindestens gleich, besser jedoch höher ist, als die optimale Gasgeschwindigkeit für den ersten Peak, gemessen bei der Starttemperatur (Temperaturprogramm) oder bei der eingestellten Ofentemperatur (isotherme Fahrweise).
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  • 54
    ISSN: 1612-1112
    Keywords: Configuration ; Chiral phases ; Gas chromatography ; Isovaline
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The D-(resp. R) configuration of isovaline (=2-ethylalanine) was proved for the peptide antibiotics antiamoebin, Tü 165 (CBS 382.62), stilbellin, samarosporin (=emerimicin IV), suzukacillin B (A), trichotoxin A-40 and A-50. This contradicts the previously reported L-configuration for isovaline in antiamoebin and emerimicin IV. The configuration was determined by GC of the N-trifluoroacetyl-isovaline n-propyl ester on glass capillary columns coated with the chiral stationary phase N-propionyl-L-valine tert.-butylamide polysiloxane (Chirasil Val). The D-configuration of the isovaline from trichotoxin A-40 was also established independently using GC of N-pentafluoro-propionyl-isovaline (+)-3-methyl-2-butyl esters on glass capillary columns coated with OV 17.
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