bluuebunny/crossref_metadata_2025_split huggingface dataset:
Separation of pesticides by capillary gas chromatography. Part 1: s‐Triazines and substituted urea herbicides
Authors: Deleu R. , Copin A. 
Published: May 2005

AbstractThe authors have shown that capillary columns are perfectly adequate for the separation of s‐triazine herbicides and urea herbicides. The method presented remains adequate when the initial molecules are accompanied by some of their metabolites.
Computer supported comparison of gas chromatographic analyses
Authors: Janssens G. , Beernaert H. 
Published: May 2005

AbstractThe application of a Hewlett‐Packard 3354 B Laboratory Automation System has been studied in order to compare a series of gas chromatographic analyses. A computer program has been designed for the chromatogram reconstruction of all valid sample runs from a system subsequence on an HP‐2648 A graphics CRT terminal. The detector signals of the runs are compensated for variations in injected sample sizes when a number of conditions are met.
Continuous development HPTLC and sequential wavelength scanning for the simultaneous determination of nine clinically important β‐blocking drugs
Authors: Zhou L. , Poole C. F. , Triska J. , Zlatkis A. 
Published: May 2005

AbstractHigh performance thin‐layer chromatography was used for the separation of nine therapeutically important and structurally similar β‐adrenoceptor blocking drugs on silica gel plates. In situ scanning of the plate in the reflectance mode gave detection limits in the low nanogram range depending on the individual drug and the wavelength selected for its determination. Scanning the HPTLC plate at several wavelengths can be used to aid the identification of partially resolved components. Continuous development and continuous multiple development techniques are compared for the simultaneous separation of the drug mixture.
Detection of metal ions by glass capillary gas‐chromatographic separation of their volatile chelates
Authors: Sucre Leopoldo , Jennings Walter 
Published: May 2005

AbstractThe utility of several glass capillary columns to separate some trifluoroacetonates, diethyldithiocarbamates, di(trifluoroethyl) dilithiocarbamates and diisopropyldithiophosphates metal chelates was investigated. The increased sensitivity offered by selective detectors was also explored. Most favorable results were obtained with a short highly inert fused silica column, coated with a non‐retentive liquid phase.
Persilylation of glass capillary columns. Part 4: Discussion of parameters
Authors: Grob K. 
Published: May 2005

AbstractPersilylated glass capillary columns are the most universal GC columns available. They are relatively easy to prepare, but there is nevertheless a great need for helpful practical instructions. In the recent literature, methods and conditions for the preparation of persilylated columns have been recommended, but these might confuse the individual column maker, since they seem to originate from limited observations rather than from comprehensive investigation. They will hardly help to make column preparation safer. This paper attempts a summarized view of the present experience with persilylation and provides basic information for column makers.
Analysis of Alaskan crude oils by glass capillary gas chromatography/mass spectrometry
Authors: Hood L. V. S. , Erikson C. M. 
Published: May 2005

AbstractGlass capillary gas chromatography/mass spectrometry is used to profile Alaskan crude oil for purposes of origin verification. Alaskan oil, sampled at Valdez, Alaska, and transshipped to the U.S. East Coast, is compared with 21 samples of foreign crude oil using GC/MS techniques in which original data is reconstructed at selected parent and fragment ions to generate a series of chromatographic profiles. Comparison of selected profiles and compositional parameters derived from peak ratios allows distinction of Alaskan oil from many foreign crudes and may be applied to the examination of crude mixtures.
Surface modification of soft‐glass capillaries for gas chromatography by treatment with water vapour
Authors: Neu H. J. , Heeg F. J. 
Published: May 2005

Abstract“Leaching” or “etching” by strong mineral acids seems to be a necessary pretreatment step for the most commonly used deactivation procedures of glass capillaries by reaction with either polyethylene glycol or silylation reagents. The acidic sites which are formed on the surface during this acid treatment cannot be completely removed by the subsequent deactivation process. This drawback can be overcome by performing the leaching with water vapour, resulting in an accumulation of cations at the surface and a decrease in the number of silanol groups. Capillaries of this type show excellent properties for the chromatography of strongly basic compounds. After the wash‐out of the alkaline surface layer, the acidity of the support is suited for the chromatography of strongly basic as well as strongly acidic compounds. Due to a lack of reactive acidic sites, special deactivation procedures have to be applied to capillaries produced in this way.
Analysis of sludge extracts by high resolution GC with selective detectors
Authors: Lopez‐Avila Viorica 
Published: May 2005

AbstractCombination of various GC detectors by using a Varian effluent splitter with glass capillary columns has been found to be a rapid procedure for profiling organics extracted from sludges and river sediments. The selectivity and the increased sensitivity of the thermionic nitrogen‐phosphorus detector (TSD), the electron capture detector (ECD), and the flame photometric detector (FPD) over the flame ionization detectors (FID) or mass spectrometers allow the detection of compounds present at trace levels without need for extensive sample cleanup. Furthermore, the combination of two selective detectors may supplement the information with regard to the chemical functionalities required for structure elucidation.
The theoretical basis of column chromatography in multicomponent separations. Part 1: Analytical requirements and peak resolution. Development of a high performance column system
Authors: Peichang Lu , Xiuzhen Li , Yukuei Zhang 
Published: May 2005

AbstractThe point of our published papers since 1957 is reviewed. The relations between the required value of peak resolution, K1 (or R), and peak separation, K3 (eqn 9); K1 and relative accuracy of a peak height quantitative method, Ph (eqn. 10); K1 and relative accuracy of a peak area method, Pa, (eqn. 12) at different concentration ratios, ϕ, are derived. The final result in Table 2 shows a large influence of ϕ on the required value of K1.The approximately linear relation between peak width and retention value (eqn. 18) exists not only in GC. but also in HPLC. Plate height values H1 and H∞ for a solute with capacity ratio, k′, equal to unity or approaching infinity, respectively, are used to evaluate the column efficiency (eqn. 20). The measuring methods (eqn. 21,22,23) and parameters effecting on H1 and H∞ are given for GC packed column (eqn. 24), GC open tubular column (eqn. 25) and HPLC (eqn. 26). In the light of this, columns of high efficiency were developed. Some typical chromatograms for high speed analysis and separation of complex mixtures are given.
The varigrad and similar apparatus in gradient liquid chromatography: A systematic computational approach. Part 2: Applications
Authors: Said A. S. 
Published: May 2005

AbstractPart 2 deals with the application of the equations derived in Part 1 to the systematic calculations of the constant volume and hydrostatic Varigrads. Examples are given which illustrate the advantage of using the modified incremental method of gradient elution. The non‐homogeneous Varigrad, where mixing chambers may vary in volume, is also treated.
A quaternary solvent system for the reverse‐phase liquid‐chromatographic separation of polycyclic aromatics
Authors: Smith T. R. , Strickler V. A. 
Published: May 2005

AbstractModern liquid chromatographic (LC) conditions which effect a separation of polycyclic aromatic hydrocarbons (PAH) containing up to ten rings are described. The LC conditions include reverse‐phase chromatographic columns in combination with a quaternary solvent system. Methanol and water are combined to form solvent system A, while tetrahydrofuran and acetonitrile form solvent system B. Solvent systems A and B are then combined in a linear gradient relationship to effect the separation. The separation of benzo(a)pyrene and perylene along with benzo(ghi)perylene and indeno (1,2,3‐cd)pyrene is achieved. In the same chromatogram the PAHs, coronene, dibenzo(a,e), (a,i), (a,h)pyrene and tribenzo(a,e,i)pyrene are also separated. An increase in column temperature from 45°C to 55°C is shown to shorten the elution time and increase chromatographic resolution of many of the PAHs examined. At least 25 PAHs ranging in molecular weight from 178 to 536 are examined for their chromatographic behavior. As examples, the application of this method to samples from a coal liquefication process are included. The samples are examined with both a UV detector and fluouescence detector to demonstrate the utility of dual detectors when analyzing for PAHs in complex matrices. With minor modification of the gradient this method is applicable to PAHs containing ring systems other than those reported here.
Thin‐layer adsorption chromatography with mixed mobile phases. 4. Extension of Ościk's equation to heterogeneous adsorbents
Authors: Różyło J. K. , Ościk J. , Ościk‐Mendyk B. , Jaroniec M. 
Published: May 2005

AbstractIn this paper the equation for thin‐layer adsorption chromatography with multicomponent mobile phases, proposed by Ościk in 1965 is extended to energetically heterogeneous solid surfaces. Other forms of this equation, more convenient in practical applications, are presented. Model calculations are made for TLC with binary mobile phases according to the modified form of Ościk's equation. Finally, this equation is compared with that of Snyder.
Quantitative analysis of some preservatives in pharmaceutical formulations by different chromatographic methods
Authors: Koršič J. , Milivojevič D. , Smerkolj R. , Kučan E. , Prošek M. 
Published: May 2005

AbstractDifferent chromatographic methods for determination of methyl hydroxybenzoate and propyl hydroxybenzoate in pharmaceutical formulations are compared. Procedures for HPTLC, HPLC and GC/MS are given.
The effect of temperature on the efficiency parameters in adsorptive liquid chromatography
Authors: Herbut Genowefa , Kowalczyk Jerzy S. 
Published: May 2005

AbstractThe effect of temperature on the efficiency of column systems in adsorptive liquid chromatography is reported. The influence of temperature changes on the values of the terms Cm2 and Ck in the HETP equation, which characterizessystems involving silica gel and benzene, ethylene chloride, butyl ether or cyclo‐ hexanone + heptane, is discussed for 9 substances. The results of the study have led to the following conclusions:

Temperature increase will always improve the efficiency of typical chromatographic systems.
As expected, an essential role is played by mass transfer resistance in the mobile phase occupying the pores of the packing material (parameter Cm2).
Mass transfer resistance resulting from sorption‐desorption kinetics (Ck) does not play as essential a role in the systems investigated as does Cm2, but its value is significantly higher than that reported in the literature.
Direct LC analysis of selected priority pollutants in water at ppb levels
Authors: Allan Pinkerton K. 
Published: May 2005

AbstractThirty‐two priority pollutants can be analyzed in water with detection limits of 10 ppb by direct liquid chromatography. High sensitivity is obtained by use of an ultra‐violet detector at 202 nm and a reverse phase C18 column with a water‐acetonitrile gradient that is compatible with two milliliter water samples.
Analysis of cardenolides of Convallaria majalis by high pressure liquid chromatography
Authors: Harkiss K. J. , Linley P. A. , Mesbah M. K. M. 
Published: May 2005

AbstractCardenolides of Convallaria majalis were separated by reverse‐phase HPLC on Partisil PXS 10/25 ODS columns using 25% acetonitrile as mobile phase. Periplorhamnoside, convallatoxin and either convallatoxol or convalloside were resolved from glycoside mixtures. Convallatoxin and periplorhamnoside were identified in plant extracts, convalloside and convallatoxol were not resolved from non‐cardenolide material present in leaf extracts.
Column chromatography fractionation of complex waste water sample extracts for measurement of ppt levels of 2,3,7,8‐tetrachlorodibenzo‐p‐dioxin
Authors: Nowicki H. G. , Kieda C. A. , Current V. , Schaefers T. H. 
Published: May 2005

AbstractThe novel application of azulene as a visual monitor of column chromatography performance during fractionation of complex waste water extracts for measurement of 2,3,7,8‐tetrachlorodibenzo‐p‐dioxin (TCDD) at part‐per‐trillion concentrations is described. TCDD elutes directly behind azulene, the blue visual aid, in the 6% ethyl ether/hexane fraction during Florisil column chromatography.
Qualitative evaluation of aromatic herbs by direct head space (GC)2 analysis. Methodology and some preliminary applications
Authors: Gabri G. , Chialva F. 
Published: May 2005

AbstractA simple, quick method is described for GC head space evaluation of herbs and drugs. The proposed procedure consists of milling a weighed sample of a certain herb in a glass device like a Braun MXK coffee grinder, modified in such a way that a special gas‐tight valve allows the direct sampling of the vapors. Glass capillary columns are used to analyze the head space volatiles. Some preliminary applications of the method are given.
Thermal aqueous liquid chromatography—the TALC technique
Authors: Guillemin C. L. , Millet J. L. , Dubois J. 
Published: May 2005

AbstractThermal Aqueous Liquid Chromatography (TALC) using pure water as a mobile phase should be a very attractive technique promoting the use of liquid chromatography in routine analysis, either in the laboratory or in future on‐line process control. This simple form of chromatography, the selectivity of which depends on the fixed phase only, would allow the use of flame ionization as an almost universal, low‐cost detector in liquid chromatography. The potential of the TALC technique is illustrated by selected examples.
The effect of the temperature dependence of mobile phase viscosity on the retention time in series‐coupled gas chromatographic columns
Authors: Buys T. S. , Smuts T. W. 
Published: May 2005

AbstractA previously established model of a system of series‐coupled columns, incorporating the effects of temperature and mobile phase compressibility, is generalized to take the temperature dependence of the mobile phase viscosity coefficient into account. Expressions are reported for the linear flow velocity, the effective partition coefficient, and the retention time for both the case of constant mass flow rate and that of constant overall pressure drop. Numerical results indicate that the temperature dependence of the viscosity coefficient affects the retention time and pressure drop while the effective mass distribution coefficient remains essentially unchanged.
Glass capillary columns for separation of free organic acids
Authors: Hřivnáč Milan , Sýkora‐Čechová Lenka , Müller‐Aerne Monica 
Published: May 2005

AbstractGlass capillary columns have been prepared without acidic additive in the stationary phase, from which free organic acids elute as sharp and symmetrical peaks. The required surface in the borosilicate glass capillary was generated by a combination of leaching with aqueous HCl and deposition of colloidal silica particles; it can be coated with stationary phases have a broad range of polarity. Aqueous samples containing free organic acids can also be analyzed in such columns in an isothermal mode.
Thermostable persilylated polar glass capillary columns by the ammonia‐etching method
Authors: Traitler H. , Prévôt A. 
Published: May 2005

AbstractStatic ammonia etching has been used to effect regular surface roughening of glass capillaries. Following such treatment, polar phases could be coated after persilylation with varioussilylation agents such as hexamethyl‐, tetramethyldiphenyl‐, and tetra‐ phenyldimethyldisilazane, respectively. This method produces columns of high thermostability, which is limited only by the maximum applicable temperature for the phase itself.
Effect of some parameters on the liquid chromatographic separation of biogenic amines and their metabolites
Authors: Lammers N. , Zeeman J. , De Jong G. J. 
Published: May 2005

AbstractThe liquid chromatographic separation of some biogenic amines and their metabolites with a reversed‐phase ion‐pair system has been optimized. The effects of the nature of the stationary phase, the column temperature, the pH, and the ion‐pair reagent concentration of the mobile phase have been investigated. The most striking result is the influence of the column temperature on selectivity.
Fused silica capillary GC/MS coupling: A new, innovative approach
Authors: Friedli F. 
Published: May 2005

AbstractA novel fused silica capillary GC/MS direct coupling is described which ensures quantitative transfer of sample from the point of injection to the ion source of a mass spectrometer without contacting any surfaces other than the column wall. This device permits GC analysis of highly labile substances. Aflatoxin B1, previously considered unassayable by GC, can now be determined by GC/MS.
Comparative study of efficiency and reproducibility of two high‐performance gel permeation chromatography columns with microparticulate packings
Authors: Rand W. G. , Mukherji A. K. 
Published: May 2005

AbstractTwo kinds of commercially available, microparticulate silica columns have been studied for their efficiency and reproducibility in gel permeation chromatography measurements. Results are provided for column plate height measurements, dispersity, and specific resolution as a function of flow rate. The influence of injection volume and slice width on these measurements is also presented. Reproducibility studies on polystyrene and styrene‐n‐butyl methacrylate copolymer are reported.
Capillary columns with immobilized stationary phases. Part 4: A moderately polar phase, OV‐1701
Authors: Grob K. , Grob G. 
Published: May 2005

AbstractWhereas the immobilization of apolar silicone phases is essentially understood and mastered, the corresponding treatment of even moderately polar phases remains problematical. Upon attack by peroxide radicals, these phases respond by forming active transformation products rather than by bonding to the support surface or to neighboring molecules. OV‐1701 is at present the most polar stationary phase which can reasonably be immobilized. An essential feature of the practical procedure is the prevention of film breakage after coating the inert support surface and before immobilization. Two ways of overcoming this problem are presented.
Analysis of nitrated polycyclic aromatic hydrocarbons by glass capillary gas chromatography using different detectors
Authors: Ramdahl Th. , Kveseth K. , Becher G. 
Published: May 2005

AbstractGlass capillary gas chromatography has been investigated as a method for the analysis of nitrated polycyclic aromatic hydrocarbons (nitro‐PAH) using both splitless and on‐column injection techniques. The nitro‐PAH showed good chromatographic performance and thermal stability under the GC conditions used. Retention times and response factors of several nitro‐PAH were compared to those of conventional PAH.Simultaneous flame ionization and thermionic nitrogen selective detection was used to facilitate identification of nitro‐PAH in complex samples. The feasibility of the method is demonstrated on two samples of commercial carbon black. Besides 1‐nitropyrene several isomeric dinitropyrenes have been identified.
Application of the Hall™ electrolytic conductivity detector for the analysis of chloroanilines and chloronitroanilines in POTW sludges
Authors: Lopez‐Avila V. , Northcutt R. 
Published: May 2005

AbstractSimultaneous detection with a 700‐A Hall™ and an NPD detector is an effective technique for characterizing chloro‐and chloronitroanilines in highly complex Publicly Owned Water Treatment Works (POTW) sludges. The utilization of a modified Varian effluent splitter and a SE‐54 fused silica capillary column permitted the detection of mid‐picogram quantities of the polar chloroanilines without sacrificing peak shape. The response of the Hall™ detector in the halogen mode was roughly proportional to the number of chlorine atoms present, while the response of the Hall™ in the nitrogen mode and the NPD was less predictably influenced by the presence of one or more nitro groups. When combined with retention time data, the ratio of the NPD response to the Hall™ response has been found to substantiate the presence of chloro‐ and chloronitroanilines in sludge extracts.
Influence of solvent strength in possible optimization of adsorption thin‐layer chromatography
Authors: Różyło J. K. , Chojnacka G. , Kolodziejczyk H. 
Published: May 2005

AbstractConsiderations of TLC process optimization have been based on the thermodynamic theory of adsorption from multicomponent solvents using experimental and theoretical RM1, 2 = f (Φ1) relationships. It was found that a relationship exists between the Az parameter (log k where k is the partition coefficient of the substance chromatographed) of the above theory and pKa values of substances as well as the solubility parameter δ of the mobile phase components. Analysis of the Az values of substances shows that a slight variation therein is associated with lower selectivity of chromatographic separation.
A comparative study of microbore reverse‐phase columns
Authors: Vadukul N. K. , Loscombe C. R. 
Published: May 2005

AbstractA procedure for packing reverse‐phase microbore columns using moderate pressure is described. Columns packed from different manufacturer's tubing are compared with commercially available columns. A method for coupling the column to the injection valve is suggested. The effect of detector cell volume on overall efficiency of the system is also examined.
Optimization of binary solvents in thin layer chromatography
Authors: Nurok D. , Becker R. M. , Richard M. J. , Cunningham P. D. , Gorman W. B. , Bush C. L. 
Published: May 2005

AbstractΔRf, the separation between a pair of compounds on a thin layer chromatographic plate, can be predicted as a function of solvent composition for certain binary systems. This allows the prediction of optimum solvent composition for separating a mixture of compounds by thin layer chromatography. A new solvent polarity ranking, based on calculation of ΔRf is described.
Development and evaluation of wall coated open‐tubular columns for GC analysis of individual polychlorinated biphenyl isomers
Authors: Moseley M. A. , Pellizzari E. D. 
Published: May 2005

AbstractThe present article describes the development and testing of capillary columns for analysis of individual isomers of polychlorinated and polybrominated biphenyls, pesticides, and other halogenated hydrocarbons of environmental and biological importance.
Polysiloxane deactivated fused silica capillaries containing immobilized stationary phases
Authors: Moseley M. A. , Pellizzari E. D. 
Published: May 2005

AbstractThis article describes a method of preparing immobilized stationary phases which has arisen from the authors' work on polysiloxane deactivation of fused silica capillaries. Although acid treatment is often omitted with fused silica capillaries, there are good reasons for hydrothermal treatment of this column material. Use of Grob's peroxide method gave immobilized 0.25 μm films of SE‐54; lowering of the immobilization temperature permitted immobilization of 0.1 μm films of the same phase.