bluuebunny/crossref_metadata_2025_split huggingface dataset:
Simultaneous determination of acidic, basic and alcoholic substances relating to monoamine hormones and metabolites in biological material by mass fragmentography (GC/MF)
Authors: Kobelt Reinhard , Wiesener Günther 
Published: May 2005

AbstractA method is described for the simultaneous quantitative determination of monoamines and related compounds from urine and brain tissue samples in the pg‐range, using a GC/MF instrument LKB‐2091 provided with a multiple ion detection (MID) system and capillary columns. The simultaneous detection of “fingerprints” with fourteen and more compounds during one single GC run was achieved after the intoduction of “time gates” for the detection of the different characteristic masses. Several modifications to the LKB equipment permitted exact reproducibility of retention times, which is essential for the use of “time gates”. The detection of “fingerprints” with these acidic, basic and alcoholic substances was achieved by the extraction of the dried biological samples with silylating agents.
An HPLC fluorescence detection system for amines
Authors: Frei R. W. , Lawrence J. F. , Th. Brinkman U. A. , Honigberg I. 
Published: May 2005

AbstractA detection system is described which is based on fluorescent ion‐pair formation between tertiary amine drugs and dimethoxyanthracene sulphonate. A dynamic micro‐extraction principle is then used to isolate the ion‐pairs from the excess reagent. The band broadening of this extraction detector was kept below 20% using standard auto‐analyser equipment. With the enhanced selectivity and sensitivity of this approach it was possible to analyse chloropheniramine in urine at ppb concentrations using a pre‐column clean‐up trace enrichment step.
Systematic and statistical errors in quantitative evaluation in TLC and HPTLC. 3. The determination of the primary statistical errors
Authors: Ebel S. , Glaser E. 
Published: May 2005

AbstractThe paper describes the measurement and calculation of the primary statistical errors in the evaluation of TLC or HPTLC using in situ reflectance measurements. The primary errors are the errors of the sample volume spotted onto the plate, errors caused by the chromatographic process itself, the positioning error of the plate with respect to the centre of the light beam and the error in the light measurement. By scanning the same spot, the same track or the same plate under different conditions, the various errors can be determined.
Preparation of wall‐coated open tubular columns after surface roughening by means of amorphous silica
Authors: Badings H. T. , Van der Pol J. J. G. , Wassink J. G. 
Published: May 2005

AbstractA new method for the preparation of wall‐coated glass capillary columns after surface roughening by means of amorphous silica is described. After the glass capillary has been leached, a small quantity of amorphous silica is deposited evenly on the inner surface. This is done by passing a plug of dilute water glass through the capillary, followed by a flow of gaseous hydrochloric acid. The roughened surface is stabilized, deactivated and finally coated.This paper furnishes details of the technique and information about the performance of a number of columns prepared by the method.
Are we using the full resolving power of capillary GC?
Authors: Neu H. J. , Zinburg R. 
Published: May 2005

AbstractPrecise evaluation of the chromatographic data by means of the relative retention will allow the full use of the resolution achieved by capillary columns. In practice, retention‐index determination is best suited for this purpose. The reproducibility of retention‐index determination strongly depends, among other factors, on the accuracy of retention time measurement. A reproducibility of ±0,05 i.u. can be easily achieved with modern gas chromatographic equipment, provided the retention times can be measured with an accuracy of at least ±0.01%. This can be shown by error propagation analysis of retention‐index calculation performed with the aid of a programmable pocket calculator.
Glass capillary gas chromatography of amino acid enantiomers
Authors: Nicholson Graeme J. , Frank Hartmut , Bayer Ernst 
Published: May 2005

AbstractGlass capillaries coated with Chirasil‐Val, a chirally functionalised polysiloxane, are capable in principle of resolving all protein amino‐acid enantiomers in a single run and within a short analysis time, thus allowing for example the quantitative amino acid determination by enantiomer labelling. The elution characteristics of the individual amino acids however are also dependent upon the chemical nature of the capillary wall surface, and a surface pretreatment is found to be necessary if all protein amino acids are to be analysed. Of the various methods of pretreatment tested, etching of borosilicate glass with gaseous HCl followed by deposition of colloidal silicic acid is considered to be the most suitable.
Practical limitations of capillary gas chromatography
Authors: Schomburg G. 
Published: May 2005

AbstractGlass capillary gas chromatography is a high resolution separation method which allows the qualitative and quantitative analysis of even complex mixtures, which may contain many components–also isomeric–in a wide range of volatilities, polarities and concentrations.The principal limitation of gas chromatographic application is given by an insufficient volatility of the species to be separated. Elevated temperatures have to be applied if the application range is to be extended and to achieve steep peak profiles, i.e. low detection limits at high resolution. The use of elevated temperatures is limited, of course, by the temperature stability of both the solvent (stationary liquid and support) and the solutes.The problems of trace analysis for low volatility compounds at high resolution and its limitational parameters regarding sampling, separation and detection are discussed.The applicability of glass capillary columns in this field is influenced by the following parameters: tailing behaviour; irreversible adsorption of polar and decomposition of unstable solutes; thermal stability of stationary liquid (including the support deactivation); separation efficiency and sample capacity (film thickness).Multidimensional gas chromatography using capillary columns coupled either with a packed or another capilllary column for preseparations may be applied with advantage in the analysis of complex mixtures.
Effects of the porous structure of particles on selectivity in liquid chromatographic systems
Authors: Kowalczyk J. S. , Gazda K. , Herbut G. 
Published: May 2005

AbstractThe effects produced in liquid‐solid chromatography by the heterogeneity of adsorbent particles on the behaviour of a number of substances were studied. As adsorbent silica gels were used which varied

In specific surface area and pore size,
In the diameter of particles of the same microporous structure.
A second series of experiments was conducted at various temperatures.The dependences which were based on measurements of equivalent retention volumes were found to deviate somewhat from those theoretically predicted. However, they confirm and supplement some previous observations [l–5] according to which mass transport may be effected by only a portion of the packing particles if their porous structure is adequately heterogeneous. These observations are in contrast with views expressed by some authors [6, 7] who maintain that differences in mass transport resistance may only result in peak deformation.It has also been demonstrated that the effects of the heterogeneity of particle structure in liquid chromatographic systems can be reduced by increasing the temperature.
Determination of dichloroacetic acid in plasma and urine
Authors: Heizmann P. , Von Alten R. 
Published: May 2005

AbstractA method for the measurement of dichloroacetic acid in plasma or urine has been developed. The method involves extraction of dichloroacetic acid into diethyl ether, evaporation of the etheric phase to a small volume and derivatization with diazomethane. Trichloroacetic acid was used as an internal standard. Concentrations as low as 50 ng/ml can be determined.
High performance liquid chromatographic resolution of the optical isomers of D,L‐tryptophane, D,L‐5‐hydroxytryptophan and D,L‐dopa on cellulose columns
Authors: Gübitz G. , Jellenz W. , Schönleber D. 
Published: May 2005

AbstractThe application of HPLC for the purpose of separation of some amino acid racemates with aromatic substituents is described.Using simple untreated cellulose with an average particle size of 7 μm as stationary phase, complete resolution of D,L‐tryptophane and D,L‐5‐hydroxytryptophane can be obtained. D,L‐3,4‐dihydroxyphenylalanine is resolved partially.The α‐value and resolution for D,L‐tryptophane was found to be 1.5.
Effect of test temperature on separation number
Authors: Jennings Walter , Yabumoto Kan 
Published: May 2005

AbstractThe separation number is affected by a variety of extra‐column factors (e.g. the injection process, the nature of the sample, and plumbing defects in the inlet and detector) as well as factors related to column efficiency. The magnitude of the separation number, as affected by the column, varies inversely with column temperature and directly with the partition ratios of the test compounds. The interrelationships of column temperature and partition ratios are explored.
HPLC of fatty acid esters of mono‐ and polyhydric alcohols. Part 2: Preparative separation
Authors: Henke H. , Dietrich W. 
Published: May 2005

AbstractThis paper demonstrates how simply and rapidly fatty acid esters of mono‐ and polyhydric alcohols can be separated quantitatively in preparative quantities on Lobar® RP‐8 packed columns. After the separation of unknown mixtures, the isolated esters are identified from spectroscopic data (IR/NMR) and, after saponification of the ester components (fatty acids and alcohols), from the retention times of gas and high‐pressure liquid chromatographic separations. Thus, in particular, sparingly volatile or nonvolatile partial esters of polyhydric alcohols, as well as the long‐chained full esters, can be determined qualitatively and quantitatively.The following fatty acid esters of mono‐ and polyhydric alcohols have been separated: the i‐propylesters of the laurinic and myristinic acids, the i‐butyl‐, i‐octyl‐ and i‐octadecyl‐esters of the palmitinic and stearic acids, the mono‐ and di‐fatty acid esters of the 1,3‐bis‐(2‐hydroxyethyl)‐5,5‐dimethylhydantoins, the mono‐, di‐ and tri‐esters of the trimethylalpropane and the full esters of the pentaerythrite.
Influence of chamber saturation in thin‐layer chromatography on theoretical and experimental parameters of mixture separations
Authors: Różyło J. K. , Ościk‐Mendyk B. 
Published: May 2005

AbstractThe influence of chamber saturation in thin‐layer chromatography on theoretical and experimental parameters of mixture separations were examined. Five different types of chambers for development of chromatograms were taken into consideration. The relation found experimentally differed widely from that calculated using Ościk's equation for different method of carrying out of the chromatographic process. The investigations presented here show the possibility of choosing chromatographic chambers which are optimum for theoretical studies on the process of thin‐layer chromatography.
Analysis of drugs and related compounds by capillary column GLC
Authors: Vandenheuvel W. J. A. , Zweig J. S. 
Published: May 2005

AbstractThis article describes the development of the application of capillary column GLC methods to steroids, prostaglandins and especially drugs and their metabolites in samples of biological origin. The wide variety – in terms of structures and pharmacological properties – of drugs now analyzed by capillary column GLC is made evident. Reasons for use of capillary rather than packed columns are given. The frequent use of and need for derivatization procedures prior to chromatography is emphasized. A bibliography of 83 references is included in the manuscript.
Chromatogram surgery
Authors: Janssens G. 
Published: May 2005

AbstractA computer program is developed on a Hewlett‐Packard 3354 B Laboratory Automation System to eliminate background in gas and liquid chromatograms. Moreover undesired peaks, such as solvent peaks and spikes, can be excluded by selecting appropriate method parameters or by application of the integrator‐timed events directly affecting peak integration. Injudicious application of these codes deforms the chromatograms. Peaks can be labelled with retention times, areas or amounts.
Determination of adsorption by fluorescence in gas chromatography
Authors: Driessen O. , Lugtenberg J. 
Published: May 2005

AbstractPMBF2, a pyrromethene pigment, can be used in gas chromatography. Because of its fluorescence, adsorption sites on glass columns and connections can be traced in situ. The compound can be employed to check the inertness of glass surfaces after deactivation procedures. Some applications are described.
Volatile phase profiling of mainstream smoke by glass capillary gas‐chromatographic techniques
Authors: Good B. W. , Parrish M. E. , Douglas D. R. 
Published: May 2005

AbstractA heated injection system for a microprocessor‐controlled GC has been developed for the (GC)2 analysis of the volatile phase of whole smoke of a cigarette. Effects of injection port temperature and the presence of a Cambridge filter pad are demonstrated. Chromatograms are shown for smoke samples with and without a Cambridge Filter with the sample valve oven at 25°, 165° and 205°C. The use of a flame ionization and a nitrogen‐phosphorous detector is illustrated.
Evolution and application of the fused silica column
Authors: Jennings Walter 
Published: May 2005

AbstractFused silica is an evolutionary product of continuing efforts to improve our chromatographic capabilities. It offers the normal user new horizons in inertness, chromatographic reproducibility, ease of column installation, and possibilities in on‐column trapping. Since this writing, chemically bonded phases in several film thicknesses became available on fused silica columns, and these are especially well suited to on‐column injections. The use of fused silica syringe needles to inject directly onto fused silica columns seems particularly interesting. Evolution is, of course, a continuous process and it would appear that we can expect continuing developments in this exciting area.
The theoretical basis of column chromatography in multicomponent separations. Part 2: Peak capacity. Column systems with good selectivity
Authors: Peichang Lu , Xiuzhen Li , Yukuei Zhang 
Published: May 2005

AbstractThe selectivity of a column system, S, defined by equation 28, includes a variation coefficient (β) of plate number with capacity ratio which has a large influence on the peak capacity, as shown in Fig. 18. Some typical chromatograms are given. In order to predict S for a column system from Kovat's Index, equations 40 and 41 are given to calculate the constant of the carbon number rule for squalane at different temperatures or for different stationary phases. The specific retention value of heptane on squalane at different temperatures can be calculated from equation 42. The nonpolarity index, defined by equation 43, was used to calculate the retention value of heptane on various stationary phases. In liquid chromatography, the order of elution may be reversed by changing the composition of the eluent on the same chemically bonded silica (manufactured in China). The linear relations between the log retention values of different kinds of solutes or of a single solute on the silicas of different surface areas when using the same eluent are given.
Day‐dream on process and laboratory gas chromatography
Authors: Guillemin C. L. 
Published: May 2005

AbstractThree main problems have to be solved in process gas chromatography: psychological, technical and economic.A simple concept already used with success for fifteen years by the author, called the Deferred Standard, is an answer for process GC and, to some extent, laboratory GC as well.That the injection of a pure compound in each analytical sequence is reproducible demonstrates the good working order of PGC. Accurate quantitative results may be obtained because the gas density balance is used as a calibrator detector for determining the relative response factors of the components of interest with respect to the Deferred Standard.By suppressing any calibration standards in process and laboratory chromatography, the Deferred Standard may reveal itself as a time and money saving technique.
Evaluation of syringe handling techniques for injections into vaporizing GC injectors
Authors: Grob K. , Rennhard S. 
Published: May 2005

AbstractUnequal elution of sample components of different volatility out of the syringe needle is one of the major causes for discrimination occuring during the injection, i.e. the phenomena which results in peak areas for the high boiling compounds which are too small compared with the volatiles. This problem, associated with all vaporizing injectors that are used with syringes, can be minimized by careful choice of the needle handling technique. Various methods are compared experimentally. The “solvent flush” method is discussed in detail and demonstrated to be ineffective for reducing losses in the syringe needle. The “hot needle” technique, where the empty needle is preheated in the injector before pushing the plunger, was found to be superior or equal to an improved “solvent flush” method (which included preheating the needle and omitting the air plug between sample and flushing solvent. Generally it was found that the discrimination due to the syringe needle was reduced for larger sample volumes, although no further changes were noticed when these exceeded 2.5 to 3μl.
Simultaneous analysis of all five organic priority pollutant fractions
Authors: Trussell A. R. , Moncur J. G. , Lieu Fong‐Yi , Leong L. Y. C. 
Published: May 2005

AbstractAcrolein, acrylonitrile, volatile organics, base/neutral extractables, acid extractables, and pesticide fraction organics are analyzed in a single chromatographic run. This is accomplished by injecting the extractable organics, then applying a cryogenic focus to the front of the column, and desorbing the volatile components. The column utilized for this procedure is a fused silica open tubular (FSOT) column coated with the liquid phase SE‐54. Minimum detection limits of this procedure by electron impact GC/MS are shown to be⩽ 1 μg/liter in tests conducted on actual water samples.
Glass wool in the inserts of split injectors for capillary GC?
Authors: Grob K. , Neukom H. P. , Hilling P. 
Published: May 2005

AbstractIt has been reported that glass wool packed tightly into the glass liner of a vaporizing injector used in the splitting mode considerably reduces the standard deviation of the results obtained, because of improved evaporation of the sample prior to reaching the split point at the capillary column entrance. This finding could not be reproduced on using the same sample composition as reported in the literature, i.e. methanol/2‐ethyl‐1‐hexanol (1:1).The standard deviations obtained were between 3 and 10% (depending on the conditions selected) and were not influenced significantly by the introduction of glass wool.The peak area ratio (methanol/2‐ethyl‐1‐hexanol) was found to depend on a number of parameters, such as: injector temperature; glass liner internal diameter; syringe handling technique; the relative position of the syringe needle exit and capillary column entrance; the sample volume injected; and the packing of the glass liner. Generally, the area ratio deviated further from the correct one (determined by cold on‐column sampling) when the glass liner was packed with glass wool.On the basis of the results, it is speculated that either a complete evaporation of the sample should be achieved (which appears to be impossible under the conditions we used) or, alternatively, the sample should be given the least possible opportunity to evaporate, thus allowing it to enter the column in the form of droplets. The results were worse in terms of precision and accuracy the greater the partition of sample components between the liquid (droplet) and vapor phase. It is concluded that the use of evaporation aids such as glass wool cannot be generally recommended.
Separation of digitalis cardenolides by HPLC
Authors: Linley P. A. , Mohamed A. G. M. 
Published: May 2005

AbstractThe separation of Digitalis cardenolides has been carried out by HPLC on an adsorbent column. By choice of suitable mobile phase, isocratic elution permitted resolution of mixtures of (a) aglycones, (b) secondary glycosides, and (c) primary glycosides, while gradient elution provided a means of resolving more complex mixtures of these cardiac steroids. HPLC could therefore be used in the quality control of cardiotonic drugs replacing the TLC tests for related compounds currently used, and by suitable calibration could replace the colorimetric assay procedure normally used for such drugs.
Influence of structure and polarity of polysiloxanes on retention of N‐TFA butyl esters of amino acids
Authors: Boudah Fawzia , Abdeddaim Khélifa , Guermouche Moulay‐Hassane 
Published: May 2005

AbstractIn this work, we have investigated the influence of the polarities and structures of 13 polysiloxanes on the retention of some N‐TFA N‐butyl esters of amino acids. Gehrke [1] was the first to examine the possible relationship between polarity and retention data of amino acid derivatives for 9 stationary liquid phases. He concluded that the molecular structure of the stationary liquid phase is an important factor determining retention.
Application of ion‐exchange resin coated plates for thin‐layer chromatography of sulfonamides and some other chemotherapeutic compounds
Authors: Pauncz Judit Kádár 
Published: May 2005

AbstractA thin‐layer chromatographic method is described for sulfonamides and some other chemotherapeutic compounds. Ion‐exchange resin precoated plates (Fixion 50 × 8 Na+, Chinoin, Budapest or Polygram Ionex‐25 SA‐Na, Macherey‐Nagel and Co.,Düren, FRG) are employed with Na2HPO4 or Na‐acetate (adjusted to different pH values) containing NaCl and tert‐butyl alcohol or ethanol as developing solvent system. For qualitative and/or semiquantitave determinations the chromatograms can be stained: (A) with o‐tolidine, after chlorination; (B) with p‐dimethylaminobenzaldehyde; (C) with p‐dimethylaminocinnamaldehyde.
High speed liquid chromatography with small bore columns
Authors: Xiuzhen Li , Guimin Zhou , Miansheng Bao , Yukui Zhang , Peichang Lu 
Published: May 2005

AbstractUsing a specially designed column system, we have systematically investigated the effect of mobile phase velocity on column efficiency. The performance of small bore columns operated at different linear velocities of mobile phase was examined for three different types of injection system. Using the value of H∞/u or n∞/t as a criterion of a high speed separation, we calculated values of n/t for different solutes according to the equation \documentclass{article}\pagestyle{empty}\begin{document}$ {{\rm n}\mathord{\left/ {\vphantom {{\rm n} {{\rm t}_{\rm r}^ \circ }}}\right. \kern-\nulldelimiterspace} {{\rm t}_{\rm r}^ \circ }} = {{{\rm n}^\infty } \mathord{\left/ {\vphantom {{{\rm n}^\infty } {{\rm t}_{\rm r}^ \circ }}} \right. \kern-\nulldelimiterspace} {{\rm t}_{\rm r}^ \circ }}\left({\frac{{1 + {\rm k'}}}{{{\rm k' + }\beta }}} \right)^2 $\end{document}; the results obtained are in agreement with the experimentally determined values. These systematic investigations culminated in the separation of seven compounds in less than 10 s; the respective chromatogram is shown.
High performance liquid chromatography/video fluorometry. Part II: Applications
Authors: Shelly D. C. , Fogarty M. P. , Warner I. M. 
Published: May 2005

AbstractA video fluorometer is used as a detector for HPLC to characterize highly complex samples. Data selection and evaluation techniques are discussed so as to speed the spectral identification process. Several well‐known polynuclear aromatic hydrocarbons are found in the samples.