bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dual capillary gas chromatographic analysis of alcohols and methyl tert‐butyl ether in gasolines
Authors: Levy J. M. , Yancey J. A. 
Published: May 2005

AbstractA gas chromatographic method has been developed for the identification and direct determination of alcohols and methyl tert‐butyl ether (MTBE) in gasolines. The technique involves simultaneous injection of the gasoline without any sample preparation onto two fused silica capillary columns of differing polarities. The method permits simultaneous determinations of methanol, ethanol, 2‐propanol, tert‐butanol, 1‐propanol, sec‐butanol, 1‐butanol, and MTBE. By using an automatic sampler in combination with electronic pressure programming and BASIC programming, the determinations were performed automatically and reproducibly with a relatively short analysis time.
Automated determination of nifedipine in human plasma by capillary gas chromatography with electron capture detection
Authors: Lutz D. , Ilias E. , Jaeger H. 
Published: May 2005

AbstractA rapid, sensitive, and reliable method for the determination of nifedipine in human plasma is described. Using a single‐step solvent extraction and capillary gas chromatography combined with electron capture detection, an assay sensitivity of 2 ng/ml is achieved routinely using 0.5 ml of plasma. Intact nifedipine is quantitated and separated from its nitroso‐ and nitropyridine‐derivatives. The suitability of the assay for pharmacokinetic studies is illustrated.
Multidimensional GC with macrobore WCOT and PLOT Columns
Authors: Naizhong Z. , Green L. E. 
Published: May 2005

AbstractMultidimensional GC (MDGC) with macrobore WCOT and PLOT columns has shown several benefits: (1) Higher flow rates, which are used, makes possible the use of common valves as the switching device; (2) very simple system configurations are possible; (3) because the columns have relatively large capacity, the TCD can be used to measure both organic and inorganic components; (4) micropacked or open tubular columns are precolumns which provide a wide range of selectivity; (5) both precolumn and analytical columns can be operated at the same flow rate without splitting of the sample. Four rapid sample analyses: (1) Oxygenates in gasohol; (2) natural gas; (3) refinery gas; (4) hydrocarbon types in naphtha, have been developed and performed on a less complex and economical gas chromatograph.
Separation and detection of doxylamine and its rhesus monkey urinary metabolites by high resolution gas chromatography utilizing nitrogen/phosphorus detection
Authors: Rushing L. G. , Gosnell A. B. , Holder C. L. , Korfmacher W. A. , Slikker W. 
Published: May 2005

AbstractA high resolution gas chromatographic method is described for the separation of rhesus monkey urinary metabolites of doxylamine with the use of on‐column injection, a fused silica column (DB‐1701), and nitrogen/phosphorus detection. An ancillary separation of doxylamine and six other antihistamines is also presented.
High resolution chromatographic techniques for the evaluation of atmospheric pollutants
Authors: Liberti A. , Ciccioli P. 
Published: May 2005

AbstractThe use of high resolution chromatographic techniques for the determination of species of great importance in atmospheric pollution is critically reviewed. Attention has been focused on those pollutants recently recognized to be responsible for biological activity of particulate matter, acid deposition, and photochemical smog generation. The unique contribution made by capillary GC to the solution of environmental problems is demonstrated by the results obtained in the identification of several nitrofluoranthene/pyrene isomers in urban dust, industrial emissions, and automobile exhaust and by the selective determination of 2,3,7,8‐tetrachlorodibenzo‐ρ‐dioxin in fly‐ash emitted from urban incinerators. Also organic components dissolved in rain‐water can be analyzed by capillary chromatography after sample enrichment on traps filled with solid sorbents. The recent availability of sampling precedures suitable for the collection of gaseous species which play an important role in acid deposition makes possible their determination by chromatographic techniques. Inorganic acids, sampled through high efficiency annular denuders to obtain discrimination between gaseous species and aerosols, can be determined by ion chromatography. Peroxyacyl nitrates, relevant to photochemical pollution, can be determined by GC combined with electron capture detection. New fields of application for high resolution chromatography are discussed.
Gas chromatography of amino acids: Use of a fused‐silica capillary column in the determination of plasma amino acids
Authors: Labadarios D. , Moodie I. M. , Burger J. , Shephard G. S. 
Published: May 2005

AbstractA capillary chromatographic procedure using a fused silica column is described which can be used to quantitatively determine amino acids in plasma following the pre‐chromatographic “clean‐up” described in a recent paper [1]. In substituting this procedure for that involving a packed column, advantage has been taken of the greater resolving power to separate amino acids from background component peaks. In order to extend this advantage and provide a sound basis for quantitative analysis, the technique of cold on‐column injection was employed. As a result, good precision of standard analysis was obtained with relative standard deviation (RSD) values for all amino acids of less than 4%. Application of the entire procedure to plasma samples yields RSD values of better than 10% for all amino acids with recoveries ranging from 72% to 104%. Simultaneous determination of plasma amino acid levels by gas chromatography (GC) using capillary columns and by classical ion exchange (CIE) showed reasonable agreement. Statistical evaluation showed no significant difference between twelve amino acids. Values for the remaining two, namely, phenylalanine and histidine are significantly different (p < 0.005). Comparison of the values obtained from GC capillary and packed columns reveals no significant difference between fourteen amino acids. Significant differences exist between results for phenylalanine and tyrosine (p < 0.001). It is concluded that there is good agreement between data obtained by GC capillary and CIE techniques and that differences between results for phenylalanine and histidine are method related.
Selective quantification of ambroxol in human plasma by HPLC
Authors: Nieder M. , Jaeger H. 
Published: May 2005

AbstractThe bronchosecretolytic drug ambroxol can be reliably quantified in human plasma by high performance liquid chromatography. Plasma is buffered alkaline, extracted with ether, and the organic solvent back‐extracted with diluted acid. An automatically sampled aliquot is separated by reversed phase HPLC; the analyte is well separated from two metabolites that interfered strongly in earlier methods. UV detection at 230 nm enables a lower limit of quantitation of 5 ng/ml. Internal standardization with propranolol allows accurate and precise quantification. Evaluation of the optimized combination of mobile and stationary phase is described, and application of the method to experimental and clinical pharmacokinetic studies is illustrated.
Isocratic networks in supercritical fluid chromatography
Authors: Leyendecker D. , Leyendecker D. , Schmitz F. P. , Klesper E. 
Published: May 2005

AbstractFor chromatography with supercritical fluids (SFC), the dependence of the capacity ratios k′ and of the mean resolution Rm on temperature and pressure is presented as a three‐dimensional diagram. A sufficient number of test chromatograms were run for the diagram to lead to an isocratic network in form of a curved surface. The isocratic network possesses a characteristic shape and contains all information about the temperature and pressure dependence of k′ and Rm for a given volume flow rate and chromatographic system. The specific system studied comprised pentane as the mobile phase, unmodified silica as the stationary phase, and a set of four polycyclic hydrocarbons as the test mixture. The isocratic net of this system allows interpolation of k′ and Rm for any temperature and pressure. Together with similar experimental data from other systems, this allows qualitative forecasts about the isocratic nets of other systems.
Determination of UV‐transparent compounds by liquid chromatography using the UV detector
Authors: Gupta P. K. , Nikelly J. G. 
Published: May 2005

AbstractAn indirect UV photometric detection technique is described in which a low concentration of a UV‐absorbing compound (UVAC) is added to the mobile phase in reversed phase liquid chromatography, thereby making it possible for non UV‐absorbing compounds such as the lower alcohols to be detected by the UV detector. This happens because the injected analyte may extract a portion of the UV absorbing compound from the mobile and/or stationary phase and the complex is co‐eluted as a positive peak at the retention time of the analyte. Alternatively, the injected analyte may appear as a negative peak if the UV‐absorbing compound is transferred to the mobile and stationary phases. In any case, the injected compound appears either as a positive or negative peak depending on the relative polarities and concentrations of all the compounds in the system. In addition, the resulting excess or deficiency of detection agent in the stationary phase is eluted separately as a positive or negative peak, indicating that the system has returned to equilibrium. In the work described herein, the chromatographic conditions and variables of the indirect photometric technique were studied to develop a quantitative HPLC method for UV‐transparent compounds. It was found that under optimal conditions it is possible to determine some analytes quantitatively at concentrations as low as 0.05%.
A high resolution GC‐analysis method for determination of C2‐C10 hydrocarbons in air samples
Authors: Matuška P. , Koval (deceased) M. , Seiler W. 
Published: May 2005

AbstractAn analytical method for the determination of non‐methane hydrocarbons (NMHC) in air was developed using simultaneously pressure and temperature programmed gas chromatography (GC) on a capillary column. The separation of C2‐C10 hydrocarbons was performed in a single GC‐run using a fused silica capillary column (FSCC) with a chemically bonded non‐polar stationary phase (CP‐Sil‐5‐CB). A combination of on‐column cryofocusing and GC reinjection provided baseline separation of C2 hydrocarbons at subambient initial temperature (−40°C). The cryofocusing was performed on the column head immersed in liquid nitrogen. Quantitative retention of all C2‐C10 hydrocarbons was achieved only when a temperature gradient is created along the cooled column section. The focused components are eluted from the column head without supplementary heating by removing the coolant. To eliminate matrix effects, the enrichment procedure was designed to remove CO2 and H2O. The detection limit was found to be 2.0 × 10−12 g propane.
Violation of the linearity principle of additivity of sorption energy in chromatography. A universal equation describing retention behavior
Authors: Golovnya R. V. , Grigoryeva D. N. 
Published: May 2005

AbstractDeviations from the additivity of energy contributions to substance sorption energies, determined on the basis of thermodynamic studies of GC behavior of homologous series of organic compounds fall into two categories: one for n‐alkanes, the other for homologous series containing a functional group. A previously derived equation is proposed for homologous series, describing the deviation from the linear dependence of retention parameters with a propagating homolog n‐alkyl chain. The equation permits calculation of retention parameters of homologs starting from the first member in gas‐liquid, gas‐solid, and liquid‐liquid systems. The results prove its universal applicability.
Fused silica capillary tube isotachophoresis using a multichannel photodiode array detector
Authors: Goto M. , Ueda Y. , Ishii D. 
Published: May 2005

AbstractIsotachophoresis carried out in a 0.25 mm i.d. fused‐silica capillary tube yielded high resolution, compared with that in a fluorinated ethylene‐propylene polymer tube. The use of an ultraviolet‐visible multichannel spectrophotometer with photodiode array as detector together with a cross flow cell (volume 0.01 μl) was investigated. The system was successfully applied to the analysis of cationic dyes such as neutral red, bismarck brown, and basic fuchsine.
High speed capillary GC on 10 m × 100 μm i.d. FSOT Columns
Authors: Proot M. , Sandra P. 
Published: May 2005

AbstractThe chromatographic performance of 10 m × 100 μm i.d. capillary columns, coated with different stationary phases, was studied. TZ‐ū plots were measured at different temperature program rates. The polarity and selectivity are strongly influenced by the temperature program rate. The analysis time depends on the capacity ratio and the selectivity factor; stationary phase selection thus is an important aspect in high speed capillary GC. A number of applications is presented and the applicability of split injection is discussed.
Refractive index detection in slurry‐packed capillary column LC
Authors: Fujimoto C. , Morita T. , Jinno K. 
Published: May 2005

AbstractAn existing commercial refractive index detector was modified for use with slurry‐packed capillary column LC systems. The cell gasket of the original detector cell was replaced by a micro cell gasket giving a volume of 0.8 μL. The relationship between detector response and the amount of sample injected was examined. The limit of detection was 2‐3 ng for di‐n‐pentyl phthalate.
Tapered versus constant diameter post‐column restrictors in capillary SFC
Authors: Bally R. W. , Cramers C. A. 
Published: May 2005

AbstractA one‐dimensional compressible flow model is used in the description of actual flow through ducts. This model serves well in the explanation and prediction of the characteristics towards signal distortion, noise, mass flow rate and influence on dead‐time behavior of end‐restrictors as used in supercritical fluid chromatography (SFC) with post‐column detection. It was experimentally verified that tapered restrictors have a better performance than constant diameter restrictors at relatively low detection temperatures (200°C).The mass flow rate of a tapered restrictor is found to be linearly proportional to applied inlet pressure, implying the same linear dependence of the product of linear velocity and on‐column density. A more than proportional rise of density will, therefore, lead to a decrease in linear velocity and vice versa. Since thermostat temperature fluctuations are directly translated into linear velocity variations, a very temperature stable thermostat has to be used.As will be discussed, this complicated dead‐time dependence on applied pressure has a large effect on the chromatographic results.
Supercritical fluid chromatography with a slurry‐packed capillary column
Authors: Hirata Y. , Nakata F. , Kawasaki M. 
Published: May 2005

AbstractA versatile system with a slurry‐packed capillary column was developed for supercritical fluid chromatography, which is capable of programming both inlet and outlet pressure independently, as well as using a restrictor to apply back pressure. This system revealed the relationships between pressure drop, flow rate, and linear velocity in pressure‐programmed supercritical fluid chromatography. In the restrictor system, both the pressure drop and the flow rate increased almost linearly with inlet pressure, while under conditions of constant pressure drop characteristic behavior was observed which depended on the density‐viscosity relationships of supercritical fluid. Resolution in the separation of polysiloxane oligomers was found to be increased by increasing the ratio of pressure drop to pressure‐programming rate, although the sensitivity decreased due to the increase in peak volume. The system controlling both inlet and outlet pressure has distinct advantages over the restrictor system controlling both inlet and outlet pressure has distinct advantages over the restrictor system in practical in practical operations.
High resolution chemically bonded fused‐silica capillary gas chromatography of organochlorine insecticides and related compounds in arable soil samples
Authors: Suzuki M. , Morimoto M. 
Published: May 2005

AbstractElectron capture gas chromatography with three chemically bonded fused‐silica capillary columns (CB‐FSCs), OV‐17, OV‐1701, and SE‐52, was performed to evaluate peak separability of 28 organochlorine insecticides and related compounds. Relative retention times and relative peak heights to aldrin were measured and calculated. OV‐17 CB‐FSC showed the best separability among the three CB‐FSCs employed and was applied to analysis of extracts from several soil samples with minimum clean‐up procedure. The chromatograms obtained demonstrated steady baseline tracings free of interference. Residue data from soil samples were also tabulated.
Application of capillary gas chromatography to environmental analysis
Authors: Matsushita H. , Iida Y. 
Published: May 2005

AbstractRoutine analytical methods for benzo[a]pyrene and nitroarenes in airborne particulates are presented. Benzo[a]pyrene in airborne particulates was easily analyzed by a capillary GC/NCIMS. Analysis time was about 10 min and analytical values obtained by this method agreed well with those by HPLC/spectrofluorometry. Nineteen nitroarenes were analyzed by capillary GC/FTD following a simple clean‐up procedure. Fifteen out of 19 nitroarenes analyzed were mutagenic for Salmonella typhimurium TA100 and TA98, and 4 nitroarenes were carcinogenic to experimental animals.
High temperature gas chromatography: The development of new aluminum clad flexible fused silica glass capillary columns coated with thermostable nonpolar phases: Part 2
Authors: Lipsky (deceased) S. R. , Duffy M. L. 
Published: May 2005

AbstractSamples, representative of certain classes of “high molecular weight” and/or less volatile substances, were analyzed by gas chromatography utilizing a new generation of aluminum clad flexible fused silica glass capillary columns containing thin films of a methyl polysioxane stationary phase capable of being operated isothermally to 400–425°C and temperature programmed to 425–440°C. The results obtained here were compared with those described in the literature discussing the latest advances in Supercritical Fluid Chromatography (SFC) in the analysis of precisely the same types of samples. In all instances, the gas chromatographic method provided superior speed of analysis, superior column efficiency, and superior resolution of the component bands. This was due to fundamental factors, favoring the diffusivity of the solutes in both the gas and liquid phases in this process at these high temperatures. Under these circumstances, it is thought that the strength of SFC mainly lies in the analysis of thermally labile samples until the advocates of this technique make more definitive strides in the handling of still higher molecular weight substances well beyond the newly expanded range of gas chromatography.
Deactivation with silazanes in chromatography, mechanism of the reaction and practical consequences in capillary GC and RP‐HPLC: A29Si CP‐MAS NMR study
Authors: van de Ven L. J. M. , Rutten G. , Rijks J. A. , De Haan J. W. 
Published: May 2005

AbstractThe reaction of Cab‐O‐Sil, a highly dispersed vitreous quartz, with hexamethyldisilazane (HMDS) was studied in the temperature range 380–500°C, using 29Si solid state NMR and other techniques. Such studies are of importance in view of deactivation procedures of fused silica at high temperatures in capillary GC.The commonly accepted reaction equation:

predominates only below ca. 400°C. Above ca. 400°C the intermediate cleavage product Me3SiNH2 reacts with surface silanol groups to form SioSiMe2NH2 + CH4. At higher temperatures these groups may ultimately form (SiO)3SiNH2 groups (analogously to the formation of bi‐and tridentate linkages starting from SiOSiMe3 groups), but (SiO)3SiNH2 groups are also directly formed at lower temperatures, simultaneously with the SiOSiMe3 groups, probably by reaction with siloxane bridges:

.The reactions of the trimethylsilylamine part of HMDS with Cab‐O‐Sil were confirmed by an independent series of silylations using N,N‐dimethyltrimethylsilylamine instead of HDMS. The presence of amino groups as SiNH2 was confirmed by FT‐IR. This may be one of the reasons why very high temperature silylation with disilazanes does not provide a satisfactory deactivation of fused silica GC columns: the active SiOH groups are “replaced” by active SiNH2 groups. However, such a material may be of interest in LC. Silylation with silazanes at ca. 350°C in humid atmosphere and/or after extensive hydroxylation (leaching) of the surface should yield sufficiently deactivated surfaces with a rather well defined surface structure.
Preparation of inert glass capillary columns coated with UCON 50 HB‐5100. An attempt to rediscover industrially produced α, ω‐polyethylene/polypropyleneglycol ethers as stationary phases in capillary gas chromatography
Authors: Blum W. 
Published: May 2005

AbstractUsing UCON 50 HB‐5100, one of the most successful stationary phases in capillary gas chromatography during the past decade, as an example, we wish to redirect attention to the excellent properties of the polyethylene/polypropyleneglycol ether copolymer coatings. Based on experience gained in work with OH‐terminated polysiloxanes, a method is described for preparing inert and relatively temperature stable chemically bonded and crosslinked coatings in a single working step. Methyltrimethoxysilane was used as coupling agent, and trifluoroacetic acid was introduced as an acidic catalyst. The reaction mechanisms involved as well as the influence of additional crosslinking on the column behavior are discussed, particularly with respect of the inertness of the coatings.
(S)‐O‐acetyllactyl chloride – a versatile chiral auxiliary in stereodifferentiation of enantiomeric flavor components
Authors: Mosandl A. , Gessner M. , Günther C. , Deger W. , Singer G. 
Published: May 2005

AbstractThe stereodifferentiation of chiral secondary alcohols, 4(5)‐alkyl‐substituted γ (δ)‐lactones via corresponding 1, 4(1, 5)‐diols, chiral 1, 3‐diols, and 1‐thioalkan‐3‐ols was carried out by diastereomeric derivatization with (S)‐O‐acetyllactyl chloride as a chiral auxiliary. This procedure is a convenient and reliable method for screening the enantiomeric composition of these naturally occurring flavor volatiles.
Isolation and purification oil glucuronides with preparative anion exchange chromatography in methanol
Authors: Delaborde S. , Loosli H.‐R. , Ponelle M. , Griesser R. , Maurer G. 
Published: May 2005

Abstract890 ml of urine of rats treated with [14C] 205–734 was desalted over an Amberlite XAD‐2 adsorption column. The methanol extract dissolved in 10 ml methanol was injected onto an anion exchange column (Nucleosil 10 SB 250 × 16 mm i.d.) equilibrated in methanol. A gradient of decreasing methanol proportionversusa 0.2Mammonium hydrogen carbonate buffer eluted a pure glucuronide of 205–734. Its structure was established by NMR, MS, UV, and IR analyses. This procedure is simple, rapid, and very selective for the compound of interest.
A study of chromatographic properties of liquid crystalline polyacrylates using WCOT columns in gas chromatography
Authors: Jadhav A. L. , Naikwadi K. P. , Rokushika S. , Hatano H. , Ohshima M. 
Published: May 2005

AbstractLiquid crystalline polyacrylates (LCPAs) are evaluated as stationary phases for capillary gas chromatography (CGC). Aromatic hydrocarbons as well as polar isomeric compounds are used as test solutes to compare the polarity of the LCPAs with a conventional polysiloxane column and a Carbowax 20M column. The relative polarity of the columns with respect to change in the lateral and terminal substituents is also discussed. Lateral substitution, polarity of the terminal group, together with the solute size, affect the LCPA selectivity.