bluuebunny/crossref_metadata_2025 huggingface dataset:
Minimum column temperature required for concurrent solvent evaporation in coupled HPLC‐GC
Authors: Grob K. , Läubli Th.
Published: May 2005

Concurrent solvent evaporation using the loop‐type HPLC‐GC interface requires that the GC oven temperature be above the eluent boiling point at the given carrier gas inlet pressure in order to prevent eluent flowing into the GC capillary column. Corresponding oven temperatures representing minimum oven temperatures for eluent transfer were experimentally determined for solvents and solvent mixtures of interest for use as HPLC eluents. Evaluation of eluents for concurrent evaporation is discussed. Recommended lengths of uncoated column inlets (pre‐columns) are derived from the mechanisms involved in solvent evaporation. Temperatures listed as minimum column temperatures for concurrently evaporating HPLC eluents are also useful for estimating maximum applicable column temperatures when working with the conventional retention gap or partially concurrent solvent evaporation techniques in coupled HPLC‐GC.
Porous ceramic bed supports for fused silica packed capillary columns used in liquid chromatography
Authors: Cortes H. J. , Pfeiffer C. D. , Richter B. E. , Stevens T. S.
Published: May 2005

Porous ceramic bed supports for fused silica packed capillary columns utilized in liquid chromatography were prepared by polymerizing solutions containing potassium silicate in‐situ within a column to create a mechanically stable, rugged, and easily constructed termination. The effect of the bed support length on efficiency, and comparisons to glass wool bed supports, were considered in terms of column efficiencies and hydrodynamic variables. Results obtained indicate better performance for the ceramic bed support.
Solvent removal/thermal desorption (SRTD) for extract concentration and capillary column injection
Authors: Hart K. M. , Pankow J. F.
Published: May 2005

Many solvent extracts must be concentrated prior to analysis. Both Kuderna‐Danish (K‐D) concentration and inert gas blowdown are commonly used. Significant losses often occur with the latter. Solvent removal/thermal desorption (SRTD) on a precolumn was investigated here as an alternative or supplement to these methods. The compounds studied included polychlorinated biphenyls (PCBs) and polybrominated biphenyls (PBBs). SRTD was carried out by injecting 100 μL of extract into a cartridge‐type precolumn, selectively volatilizing the solvent with a stream of carrier gas, then thermally desorbing the analytes to a fused silica capillary gas chromatography (GC) column. The mean total recoveries and mean standard errors obtained were 109 and ±12%, respectively. SRTD was found to give sharper peaks than were obtainable with on‐column injection. Method detection limits accessible for PCBs by capillary GC with electron impact mass spectrometry with the assistance of SRTD were estimated. Overall, SRTD was found to be an effective, rapid, high recovery concentration method for solvent extracts.
Supercritical fluid chromatographic solvatochromic modifier polarity studies
Authors: Levy J. M. , Ritchey W. M.
Published: May 2005

To understand the chromatographic process as a whole, whether it be for gas chromatography (GC), liquid chromatography (LC), or supercritical fluid chromatography (SFC), one needs to know the chemical and physical nature of the mobile and stationary phases and also the interactions that take place between analytes (solutes) and the two phases. An approach towards Investigating the ways that stationary and mobile phases contribute to chromatographic retention Involves exploring the effects of solvent polarity on the strength of the mobile phase. In SFC this could involve determining the polarity of several different modifier/carbon dioxide mobile phases. In this paper, the use of a solvatochromic indicator to learn more about the effects of SFC modifier/mobile phase polarity will be investigated and discussed using several different modifiers and a diolmodified silica column.
High resolution recycle gas chromatography with off‐line flame ionization detection
Authors: Miller R. J.
Published: May 2005

Preliminary results of a recycle system employing fused silica capillary columns are discussed. The unit, which can be operated with a pre‐column for multidimensional GC, utilizes continuous stream splitting for off‐line flame ionization detection. Commercially available rotary valves were used for recirculation of the chromatographic zone between column loops. Adsorptive activity, which is shown to be additive, is a serious limitation in the analysis of polar compounds. The successful application of recycle chromatography to increase resolution on non‐polar mixtures is demonstrated.
Rapid determination of organochlorine pesticide residues in feeds by capillary gas chromatography
Authors: Torreti L. , Simonella A. , Falgiani A. , Filipponi C. , Gramenzi F.
Published: May 2005

A simple micro‐method is described for determination of 15 organochlorine pesticide residues in mixed feeds. Clean‐up of the petroleum ether extract is by basic alumina minicolumn chromatography and quantitative identification is by capillary gas chromatography with electron capture detection. Cyanopropyl‐polysiloxane chemically bonded fused silica capillary columns have been used to perform high resolution analyses in short time as well as to overcome possible interferences by PCBs. Recovery, repeatability, and detection limits of the proposed procedure are checked and results are also reported for non random samples of 180 feeds collected in Italy.
Antihormonal agents. Part 2: HPLC of ZK 98734 and its metabolites and ZK 98299
Authors: Matlin S. A. , Wu Z. Y.
Published: May 2005

Procedures are described for the reverse phase HPLC analysis of the antihormonal steroid ZK 98734 and two of its metabolites. Conditions are developed for the HPLC of the pure drug substance and for following its pharmacokinetics and metabolism. Analysis conditions are also reported for the antiprogestin ZK 98299.
HPTLC fingerprint identification of commercial ginseng drugs ‐ reinvestigation of HPTLC of ginsenosides
Authors: Peishan Xie , Yuzhen Yan
Published: May 2005

The optimized HPTLC of ginsenosides reported in this paper shows that the recommended solvent system has a higher resolution, greater spot capacity, and better reproducibility by comparison with the established ones in the previous literature. Detection and scanning in the fluorescence mode after visualization with 5% sulfuric acid/EtOH by the dipping technique improved and enhanced the sensitivity by a factor of nine compared to the commonly used absorbance made.

Sample pretreatment by an adsorption clean‐up step on a small alumina column followed by 1‐butanol extraction instead of only a butanol‐extraction step made the chromatogram clearer, caused less background contamination, and reduced the tailing of some ginsenosides spots.

The ‘peak grouping’ method was effectively used in HPTLC fingerprint identification of various commercial ginseng medicines and the chromatograms of roots of ginseng (white and red; Panax ginseng), American ginseng (P. quinquifolium), and sanchi (P. notoginseng) obtained under recommended condition are perfectly recognizable.
An optimized gas chromatographic determination of priority pollutant phenols
Authors: Masi O. H. , Gulick W. M.
Published: May 2005

Priority pollutant phenols are determined by gas chromatography on an SE‐30 WCOT column using hydrogen carrier and flame ionization detection with dual internal standards. Linear responses over ranges ca. 12–125 ng per component are achieved and detection limits at or below 1 ng are obtained. Carrier flow and temperature program are optimized to maintain baseline resolution while affording an analysis time of less than 15 minutes.
Comparison of eluents in supercritical fluid chromatography as based on density and free volume
Authors: Schmitz F. P.
Published: May 2005

A comparative study of chromatographic properties of different supercritical eluents has been performed by considering the retention at equal density or at equal free volume for different mobile phases. At equal density, the temperature dependence of the capacity ratios of aromatic hydrocarbons is the same for different alkane mobile phases, whereas significant deviations are observed when carbon dioxide is employed as the mobile phase. At equal free volume, a comparison of the capacity ratios measured in carbon dioxide and in alkane eluents showed a pronounced similarity for the different mobile phases when the free volume was low, i.e., at high densities. With increasing free volume, the chemical differences of the alkanes on the one hand and carbon dioxide on the other become more apparent in their elution behavior. Furthermore, it is demonstrated that the free volume can also be used as a reference basis for the data of solvatochromic shift experiments.
Analysis of calcium blocker drugs in plasma, HRGC and HPLC analytical conditions for pharmacokinetic studies
Authors: Giachetti C. , Poletti P. , Zanolo G.
Published: May 2005

Calcium blocker drugs are of increasing therapeutic relevance. Verapamil, nifedipine, diltiazem, and flunarizine are the most widely applied drugs of this type. New dihydropyridines (felodipine, nitrendipine) and related agents are presently undergoing intense investigation. HRGC and HPLC were used to determine eight of these drugs in spiked plasma samples. Both methods allow separation of most of the compounds in a single run and are specific, sensitive, and reproducible both for therapeutic monitoring and for pharmacokinetic studies in man and animals.
Glass capillary gas chromatography‐mass spectrometry at high temperatures. direct analysis of free base porphyrins and metal porphyrin complexes extracted from the serpiano oil shale
Authors: Blaum W. , Richter W. J. , Eglinton G.
Published: May 2005

This contribution describes GC/MS analysis of natural petroporphyrin extracts containing alkylporphyrins either as vanadyl complexes or as demetalated free bases. The combination of high temperature glass capillary gas chromatography with mass spectrometry allows, for the first time, direct determination of electron impact mass spectra of separated alkylporphyrins, making additional purification and derivatization unnecessary. The separation is carried out on glass capillary columns coated with the high temperature‐stable medium polar, OH‐terminated, polysiloxane phases PS 086 and OV‐225‐OH. The paper gives detailed working directions for the preparation of the high temperature GC/MS‐interface, and of the high temperature stable OV‐225‐OH columns (max. working temperature 390°C).
The preparation of immobilized stationary phase fused silica capillary columns with OV‐1701‐vinyl deactivation
Authors: Arrendale R. F. , Martin R. M.
Published: May 2005

A new simplified method was developed for the preparation of immobilized stationary phase fused silica capillary columns coated with OV‐1‐vinyl, SE‐54, and OV‐1701‐vinyl. This methodology includes the application of the moderately polar stationary phase OV‐1701‐vinyl as a surface deactivation agent that may also participate in the dicumyl peroxide initiated free radical immobilization process. Practical details of the procedure are presented and applications of the laboratory‐produced columns are illustrated with capillary gas chromatographic separations of standard mixtures. Possible contributions of the OV‐1701‐vinyl deactivation layer to both crosslinking and surface bonding in the immobilization process are discussed.
Short capillary column for the separation and identification of mononitrofluoranthene and mononitropyrene isomers present in air and emission samples
Authors: Ciccioli P. , Cecinato A. , Brancaleoni E. , Liberti A.
Published: May 2005

A 15 m DB‐17 fused‐silica capillary column has been used to achieve the separation of all mononitrofluorarthene and mononitropyrene isomers. Linear Retention Indices and Relative Retention times for each component have been measured and the values were compared with those observed on DB‐5 columns, commonly used for this separation. Increased polarity of the liquid phase results in better separation of some key isomeric pairs (such as 2‐, 3‐nitrofluoranthene and 1‐nitropyrene, 8‐nitrofluoranthene), difficult to resolve on DB‐5 columns. Practical applications are reported. They include the analysis of extracts from emission samples (diesel exhaust and particles emitted by a factory manufacturing carbon electrodes) as well as atmospheric dust sampled in a urban area under different conditions.
Metal selective flame ionization detection after supercritical fluid chromatography
Authors: Morrissey M. A. , Hill H. H.
Published: May 2005

This work describes the construction and operation of a flame ionization detector for the selective detection of metal‐containing compounds after capillary supercritical fluid chromatography. Using optimal conditions for achieving metal sensitive flame ionization responses which have been established for the detector after capillary gas chromatography, initial evaluation of the detector after SFC proved promising. Like the carbon sensitive FID, it appears that the metal sensitive FID is compatible with SFC when pure carbon dioxide is used as the mobile phase. Response characteristics were found to be similar to those observed when the detector is used in gas chromatography.
Device for filling of small diameter capillaries with stationary phase solutions in liquefied gases
Authors: Janák K. , Kahle V. , Horká M. , Tesařík K.
Published: May 2005

This paper describes a high pressure device for filling small diameter capillaries with stationary phase solutions is described. A liquid is forced into the capillary column with the help of high pressure syringe whose needle (provided with a side opening) is tightened in a PTFE seal. The device allows use of liquefied gas as solvent. A detailed procedure is given for filling the capillary with stationary phase solution. The performance of the device was evaluated by filling 12 m × 15 μm i. d. glass capillary with 6.5 % (w/v) SE‐54.
Co‐solvent effects for preventing broadening or loss of early eluted peaks when using concurrent solvent evaporation in capillary GC. Part 1: Concept of the technique
Authors: Grob K. , Müller E.
Published: May 2005

The concept and some first results of a method are described for evaporating large volumes of solvent in a relatively short pre‐column (retention gap) in such a way that solvent trapping retains volatile components in the inlet up to completion of solvent evaporation. The method was developed for transferring large volumes (easily exceeding 1 ml) of HPLC eluent to GC when using on‐line coupled HPLC‐GC, but is equally suited for injecting large sample volumes (at least some 50 μl) and could be particularly useful for introducing aqueous solutions.

Concurrent solvent evaporation allows introduction of very large volumes of liquid into GC. However, peaks eluted up to some 40–80° above the column temperature during introduction of the liquid are strongly broadened due to the absence of solvent trapping. On the other hand, previous retention gap techniques involving solvent trapping were not suited for transferring very large volumes of liquid into GC. Using a relatively high boiling co‐solvent added to the sample or the HPLC eluent, advantages of concurrent solvent evaporation can be combined with solute reconcentration by solvent effects, allowing elution of sharp peaks starting at the column temperature during introduction of the sample.
Novel fused silica capillary columns: Surface modification through controlled doping of the preform‐tube
Authors: Anthony L. J. , Soto L. , Heffner S. A. , Holland R. A. , Simpson J. R. , Kosinski S. G.
Published: May 2005

A method has been developed for fabricating fused silica capillary columns which have specific surface properties but still retain the excellent strength, flexibility, and resilience of pure fused silica. By using the Modified Chemical Vapor Deposition process (MCVD), typically used for the production of optical fiber lightguides, inorganic dopants such as Al, Nd, Ge, and P can be introduced into the preform‐tube by MCVD. Doped columns have a wide range of specific surface properties, and columns with undoped fused silica prepared by MCVD are more chemically inert and less acidic than columns prepared by conventional methods. This paper describes the method for fabricating capillaries and the initial studies to characterize them.
High‐temperature silylation in the production of inert glass capillary columns. From the first experiments to the chemical mechanism
Authors: Welsch T.
Published: May 2005

This retrospective article describes the beginnings and the development of silylation methods with diverse silazanes and siloxanes at high temperatures, and stresses their role in producing modern capillary columns characterized by a high degree of thermostability and adsorptive and catalytic inertness. Particular emphasis is placed on the outstanding contributions to this field ofKurt Grob, whose persilylation techniques provided the basis for the expansion of high resolution capillary gas chromatography.
HRGC assay of antihistaminic drugs in plasma samples using a nitrogen‐phosphorus detector
Authors: Giachetti C. , Poletti P. , Zanolo G.
Published: May 2005

Thirteen antihistaminic drugs are separated on a CP‐Sil 5 capillary column and are evaluated by a NP detector after extraction of spiked plasma samples, alkalinized, in a solvent mixture of chloroform, dichloromethane, and methanol. Intra‐ and inter‐assay analyses showed high reliability, therefore this method can be usefully applied in experimental or clinical pharmacokinetic investigations.
Supercritical fluid extraction / capillary supercritical fluid chromatography / Fourier transform infrared microspectrometry of polycyclic aromatic compounds in a coal tar pitch
Authors: Raynor M. W. , Davies I. L. , Bartle K. D. , Clifford A. A. , Williams A. , Chalmers J. M. , Cook B. W.
Published: May 2005

The combination of supercritical fluid extraction, high resolution capillary supercritical fluid chromatography, and Fourier transform infrared microspectrometry is described for the separation and identification of polycyclic aromatic hydrocarbons in a coal tar pitch. The variable solvating power of the supercritical fluid was utilized to selectively fractionate the sample. The fluid extract was decompressed through a frit restrictor into the sample cavity of a cooled microvalve injector, where the analytes were deposited and concentrated for subsequent chromatographic analysis. Several of the analytes separated in the chromatograph were collected on a potassium bromide disc at a solvent elimination inter‐face for subsequent infrared analysis involving the use of an infra‐red microscope accessory. The spectra obtained show the power of this detection technique for distinguishing between isomers.
Chiral stationary phases for capillary gas chromatography: Towards higher selectivity and stability
Authors: Frank H.
Published: May 2005

Thermal stability and enantioselectivity of chiral polysiloxane stationary phases for gas chromatography depend upon the composition and purity of the polymer matrix, its functional groups, the chiral selector, and the pretreatment of the inner surface of the capillary. Under proper conditions, narrow‐bore capillaries can be prepared which may be used up to 300 °C for short times. Crosslinking of the phases is achieved by heating.
Unified capillary chromatography
Authors: Ishii D. , Niwa T. , Ohta K. , Takeuchi T.
Published: May 2005

The idea of unified capillary chromatography is described. Different‐mode separations could be carried out by changing the column temperature and the pressure by using a single system. Gas chromatographic separation of aromatic hydrocarbons followed by supercritical fluid chromatographic separation of styrene oligomers was carried out in series in a single chromatographic run.
Coupling miniaturized liquid chromatography to capillary gas chromatography (micro‐LC‐CGC): Possibilities of reversed phase LC
Authors: Duquet D. , Dewaele C. , Verzele M. , McKinley S.
Published: May 2005

Retention gaps with different polarity treatments were evaluated for reversed phase solvents. Aminopropyl‐ and cyanopropyl‐deactivated retention gaps showed the best results for methanol‐water mixtures. A reversed phase packed fused silica capillary LC column is connected on‐line with a capillary gas chromatography column. The combination was used for the analysis of diazepam in urine. Volume overloading on packed fused silica columns without loss of too much efficiency was demonstrated for propranolol.
Enantiomer separation with capillary gas chromatography columns coated with cyclodextrins. Part I: Separation of enantiomeric 2‐substituted propionic acid esters and some lower alcohols with permethylated β‐cyclodextrin
Authors: Venema A. , Tolsma P. J. A.
Published: May 2005

The applicability of permethylated β‐cyclodextrin as an enantioselective stationary phase for capillary gas chromatography has been investigated. Attention has been paid to its phase transitions in a temperature range of 40–200°C. The enantiomer separation of 2‐substituted propionates and some lower alcohols illustrates the pronounced selectivity of the permethylated β‐cyclodextrin relative to molecular geometry.
Analysis of propellant stabilizer components via packed and capillary supercritical fluid chromatography/Fourier transform infrared spectrometry
Authors: Ashraf‐Khorassani M. , Taylor L. T.
Published: May 2005

The separation of model mixtures of nitrated diphenylamine and nitrated aniline via supercritical fluid chromatography employing both capillary and packed columns is described. With highly deactivated stationary phases each mixture could be separated with 100% CO2 pressure programmed. Peak identification and peak purity were afforded by on‐line Fourier transform infrared spectrometric detection. Nitrosoaniline derivatives were observed via FTIR to have been converted to nitro derivatives on storage.
High resolution gas chromatography/mass spectrometry analysis of the environmental pollutants methylnitronaphthalenes
Authors: Arey J. , Zielinska B.
Published: May 2005

We report the linear retention indices of the 14 methylnitro‐naphthalenes on three high resolution capillary columns and their electron impact mass spectra. The analyses of the methylnitro‐naphthalenes in an ambient air sample by gas chromatography/mass spectrometry with multiple ion detection utilizing 5% phenylmethylsilicone, 50% phenylmethylsilicone, and smectic columns are shown.
A new high temperature gas chromatograph incorporating a temperature programmable direct injector
Authors: Berg J. R.
Published: May 2005

A high temperature gas chromatograph has been developed which is capable of operating at column oven temperatures up to 500°C. In addition, the detector can operate at temperatures up to 500°C, and the injector up to 450°C. The injector on this instrument is a temperature programmable direct injector, designed specifically to introduce labile or high molecular weight samples into the GC without molecular weight discrimination. The design of this GC and injector will be described, and high temperature applications will be discussed.
An application of factorial design to the development of fused silica capillary columns
Authors: Hyver K. J. , De Veaux R. D.
Published: May 2005

Stationary phase crosslinking conditions for fused silica capillary columns were optimized with the use of a factorial design experiment. This experimental strategy was chosen because it provided for the determination of two‐factor interactions. A predictive model was developed for the desired chromatographic performance parameters as a function of the variables of the crosslinking reaction. Confirmatory experiments proved the usefulness of the mathematical model which resulted in the production of capillary columns of superior performance with significant improvements in reproducibility.
Sampling techniques for SFC using peak focusing by pressure and/or temperature programming
Authors: Schomburg G. , Roeder W.
Published: May 2005

In analogy to the focusing effective in capillary GC, performed with temperature programming but also with sectional cooling of the column inlet as in multidimensional capillary GC, peak focusing can easily be attained in SFC by adjustment of the mobile phase pressure as well as the column temperature. This may be of practical use in connection with sampling techniques giving poor, i.e. broad and unsymmetrical, peak shapes. Such disturbances may occur, for example, in time controlled valve sampling over longer switching times. Generally, all other negative influences on peak shape can be suppressed or compensated by trapping within the column inlet. Special trapping devices and “retention gaps” may also be coupled to the column inlet in order to create narrow starting plug widths. Positive pressure (density) and negative temperature programs give rise to peak compression besides the increase of peak capacity of the separation.
Capillary gas chromatographic analysis of amino acids in geological environments with electron capture detection
Authors: Liu De‐Ming
Published: May 2005

Studies have been performed on the analysis of 21 amino acids using a fused‐silica open tubular (FSOT) capillary column, and electron‐capture detection (ECD) or flame‐ionization detection (FID). It was shown with the N(O)‐heptafluorobutyryl (HFB) amino acid isobutyl esters that the ECD response was several hundred times more sensitive than the FID response. The relative standard deviation (RSD) of retention relative to norleucine is determined with the ECD. RSD values for all N(O)‐HFB amino acid isobutyl esters are relatively small (≦ 0.5%). This method has been successfully applied to trace analysis of most of the amino acids from fossil brachiopods and black shales.
Use of computerized pattern recognition of triglyceride profiles in monitoring SCF‐CO2 extraction of fatty oils
Authors: Vasconcelos A. M. P. , Gonçalves M. , de Azevedo E. J. S. Gomes , da Ponte M. Nunes , das Neves H. J. Chaves
Published: May 2005

High pressure extraction of vegetable fatty oils by supercritical fluid carbon dioxide was investigated. Pressures from 9 to 20 MPa at 40°C were used. The extracts were monitored by high temperature capillary gas chromatography for sterol and tri‐glyceride composition. The quality of the extracted oils was evaluated by numerical taxonomy methods. The extraction products compared well with the characteristics of commercial fatty oils of the same vegetable origin. No significant qualitative variation was detected in the pressure range studied.
Resolution–column efficiency
Authors: Sandra P.
Published: May 2005

Column efficiency in capillary gas chromatography is discussed in terms of:

internal diameter,

stationary phase film thickness, and

selection of the carrier gas
Ultra‐sensitive UV detection in micro separation
Authors: Chervet J. P. , Ursem M. , Salzmann J. P. , Vannoort R. W.
Published: May 2005

Most UV detectors used in micro separation techniques today suffer from an enormous loss in sensitivity due to the small cell volume necessary to avoid peak dispersion. Flow cells with volumes between 10‐100 nl are normally constructed of fused silica tubing. With typical path lengths of between 50‐320 μm, a tremendous loss in sensitivity results, consistent with Beer‐Lambert's law.

We have successfully constructed an ultrasensitive UV flow cell. Its total volume does not exceed 90 nl and yet its optical path length is nearly 2 cm (20,000 μm). Due to its special design, dead volume is minimized and is comparable to that of a 3 nl capillary flow cell (on‐column). Sensitivity enhancement of 100‐500 times can easily be realized in comparison with on‐column detection. The potential of this ultra‐sensitive UV flow cell in micro separations is illustrated by applications using Capillary LC and Pakked Capillary SFC.
Determination of amino acids in urine by gas chromatography
Authors: Moodie I. M. , Hough B. J. , Labadarios D.
Published: May 2005

This report describes a convenient means of reducing the complex matrix which is responsible for interference during gas chromatographic determination of amino acids in urine. The pre‐chromatographic clean‐up employs the principle of solid phase extraction using bonded silica incorporating cation exchange groups. This approach avoids the detrimental effects on amino acid recoveries associated with resin‐based cation exchangers. In spite of significant reduction in the complexity of chromatograms, only the high efficiency and resolving power offered by the analytical capillary column (e. g. fused silica open tubular, FSOT) is sufficient for quantitative and analysis of amino acids in urine. Reproducibility data from the complete procedure are determined, coefficients of variation (CV) for most amino acids being better than 5% with a mean recovery of 96%.
Sequential determination of sugar units in reducing disaccharides by capillary gas chromatography/Fourrier‐transform infrared spectroscopy
Authors: das Neves H. J. Chaves , Riscado A. M. V.
Published: May 2005

Conversion of disaccharide reducing units into the corresponding methoximes followed by their reduction with NaBH4CN to the corresponding deoxy(methoxyamino)alditol glycosides (RCH2‐NHOCH3) introduces a constitutional asymmetry in the sugar molecule. After methylation of the resulting compounds, cleavage of the glycosidic bonds is carried out by BF3‐ catalyzed methanolysis, affording permethylated O‐methylglycosides and permethylated deoxy(methylmethoxyamino)alditols with a free −OH corresponding to the position of the glycosidic bond. Identification of the reducing moiety is achieved by GC‐FTIR and computerized retrieval of library FTIR spectra.
A review of quantitative ion exchange, high performance liquid and gas chromatographic analysis of amino acids in physiological fluids
Authors: Moodie I. M. , Shephard G. S. , Labadarios D.
Published: May 2005

Methodologies for quantitative analysis of amino acids in physiological fluids based on classical ion exchange, high performance liquid chromatography, and gas chromatography are analyzed. As judged by the relative number of reports on these techniques, it appears that classical ion exchange continues to be the main method of choice for amino acid determinations and only limited advantage has been taken of the benefits (e.g. lower capital outlay and running costs and shorter analysis times) offered by other techniques. More importantly, however, there appears to be insufficient quantitative evaluation of the methodologies used. As a result, the validity of many reports based on data from amino acid analysis of physiological samples may be questioned.
Direct enantiomer separation of chiral γ‐lactones from food and beverages by multidimensional gas chromatography
Authors: Mosandl A. , Hener U. , Hagenauer‐Hener U. , Kustermann A.
Published: May 2005

Chiral γ‐lactones from the raw flavor extract of strawberries and some commercially available fruit‐containing food and beverages were stereoanalyzed directly by multidimensional gas chromatography (MDGC) employing heart‐cutting techniques from DB‐1701 as the preseparation column onto heptakis (3‐O‐acetyl‐2,6‐di‐O‐pentyl)‐β‐cyclodextrin as the chiral stationary phase.
Dual channel detection–diode array and mass spectroscopy (El or Cl)–in HPLC
Authors: Sandra P. , Courselle P. , Steenbeke G. , Schelfaut M.
Published: May 2005

Simultaneous recording of UV and mass spectra (electron impact or chemical Ionization) in conventional HPLC is described. The LC eluent is divided into two parts; one is directed into a diode array detector and the other is introduced into the mass spectrometer via a particle beam interface. The analysis of the steroid esters of a pharmaceutical formulation illustrates the possibilities of dual channel (DAD‐MS) HPLC detection.
On‐line SFC/FT‐IR analysis of agriculturally‐related compounds
Authors: Shah S. , Taylor L. T.
Published: May 2005

Several agricultural compounds which are used as herbicide precursors have been analyzed by SFC and are detected on‐line via a flow cell FT‐IR interface. A mixture of ureas is separated on a microbore packed column; while a mixture of benzamides and anilides and a mixture of sulfonamides are separated on capillary columns. The use of 100% CO2 as the mobile phase enables an infrared spectrum of each eluting analyte to be obtained on‐line with good signal to noise ratio. The urea mixture is also separated with a conventional cyanopropyl bonded phase analytical scale packed column using a methanol‐modified CO2 mobile phase and UV detection. The separations achieved with and without modifier are compared.
Determination of volatile amines in drug substances by capillary gas chromatography
Authors: de Haan P. E. , de Jong D. , van den Berg J. H. M. , Kruse C. G.
Published: May 2005

The determination of small, water soluble amines such as aziridine and 2‐chloroethylamine, in drug substances at trace levels is described. After removal of the bulk of the drug substance by extraction or precipitation, derivatization with acid chlorides is performed. In a two‐phase (water‐organic solvent) system, this derivatization reaction is accomplished almost simultaneously with the extraction of the product to the organic layer. The organic layer is analyzed by gas chromatography using on‐column injection and selective detection. Detection limits are approx. 0.2 mg/kg for aziridine and approx. 0.5 mg/kg for 2‐chloroethylamine.
Some applications of capillary gas chromatography in clinical chemistry
Authors: Liebich H. M. , Wahl G.
Published: May 2005

Profile analysis using capillary gas chromatography is applied in clinical chemistry to detect metabolic abnormalities. Examples are the increase of the urinary excretion of aromatic acids carrying a 4‐hydroxyl group and the decrease of hippuric acid in liver cirrhosis, and the elevated concentrations and excretions of dicarboxylic, oxocarboxylic, and hydroxycarboxylic acids in diabetes mellitus. Gas chromatographic quantitations, in some instances using mass selective detection, are performed on clinically relevant constituents. An example is the investigation of plasma and urinary hippuric acid and 3‐carboxy‐4‐methyl‐5‐pro‐pyl‐2‐furanpropionic acid in different stages of renal diseases.
Dynamic headspace analysis of trace volatile components in polymeric materials by wide bore capillary gas chromatography
Authors: Tsuge S. , Kuriyama K. , Ohtani H.
Published: May 2005

A novel dynamic headspace gas chromatographic system equipped with a wide bore capillary column was constructed for direct analysis of less volatile components in polymeric materials such as coating paints. With this system, the determination of typical paint additives such as hindered amine light stabilizers and ultraviolet absorbers could be carried out within a short time.
The potential of on‐line flame photometric detection in microcolumn liquid chromatography
Authors: Kientz Ch. , Verweij A. , de Jong G. J. , Brinkman U. A. Th.
Published: May 2005

The potential of an interface for the on‐line coupling of microcolumn liquid chromatography (LC)and a flame photometric detector (FPD) has been further investigated. With the micro‐LC/FPD system, relatively high‐molecular‐weight polar compounds such as cyclic adenosine monophosphate, guanosine monophos‐ phate, glucose monophosphate, fructose monophosphate, and phytic acid were separated and selectively detected. In order to increase the sensitivity, on‐line preconcentration with a microprecolumn inserted in the rotorof a Valcovalve has been applied. Preliminary results have shown that an injection volume of at least 500 1‐11 water containing organophosphorus acids at a 5–50 ng/rnl concentration level is possible.
Polar solvents for the desorption of a liquid chromatographic precolumn coupled on‐line with a capillary gas chromatograph
Authors: Vreuls J. J. , Cuppen W. J. G. M. , Dolecka E. , Maris F. A. , de Jong G. J. , Brinkman U. A. Th.
Published: May 2005

Coupling column liquid chromatography and gas chromatography on‐line is becoming more important in analytical chemistry. Especially when large amounts of polar solvents can be introduced into the gas chromatograph without any problem, the technique will offer new possibilities. With a DPTMDS retention gap, evaporation rates and flooded zones of some solvents have been determined. Two modes of operation using partially concurrent solvent evaporation conditions are discussed: (1) injecting a sample via a loop of an LC valve followed by introduction into the gas chromatograph with an LC pump; (2) trace enrichment on a precolumn followed by on‐line desorption with n‐propanol into the gas chromatograph. Preliminary results for a splitter system, inserted between the retention gap and the analytical column which allows a considerable increase of the evaporation rate are also presented.
Applications of gas chromatography with an atomic emission detector
Authors: Wylie P. L. , Quimby B. D.
Published: May 2005

An atomic emission detector for gas chromatography has been developed which is, in principle, capable of detecting selectively any element (except helium) which can elute from a gas chromatographic column. Software methods have been developed so far for 23 elements and on isotope, including all of the organic elements along with mercury, lead, tin, silicon, and deuterium. Element‐specific analyses are shown for several petroleum, environmental, and aroma samples. A table for the detector's element‐specific detection limits, selectivities, and linear dynamic ranges is given for 12 elements and deuterium.
Analysis of C1‐ and C2‐halocarbons in ambient air from remote areas using stainless steel canister sampling, cold trap injection HRGC, and a static calibration technique
Authors: Müller S. , Oehme M.
Published: May 2005

5 ml air samples from 1.6 l stainless steel canisters were cryogenically preconcentrated before gas chromatographic separation on a thick‐film capillary using a home‐made cryotrap. Quantification in the 10–500 ppt range was carried out with an electron capture detector. Problems during the cryotrap step were caused by carrier gas contamination, water and CO2 content of the sample, and a non‐optimal heat desorption rate. Their elimination is described in detail. Compound losses by wall adsorption on stainless steel surfaces were observed when dry gases were used for standard generation. A static multipoint calibration technique using humidified He was developed allowing a precise standard generation down to 100 ppt. The concentration changes in the stainless steel canisters could be neglected over a storage period of at least 1 month as long as a sufficient degree of humidity was present. The overall reproducibility of the quantification and calibration technique is in the order of 1–2% for concentrations between 100–400 ppt when daily recalibrations are carried out.
Packing material activity in packed capillary column SFC
Authors: De Weerdt M. , Dewaele C. , Verzele M. , Sandra P.
Published: May 2005

Several commercially available and home‐made reversed phase packing materials packed in capillary columns are evaluated for SFC with pure CO2 as mobile phase. Anilines and polycyclic aromatic hydrocarbons are used as test mixture. Some “on column endcapping” experiments are evaluated.
Characteristics of an amperometric detector for capillary HPLC
Authors: Ruban V. F.
Published: May 2005

The main characteristics of a dual‐electrode amperometric detector with a cell of the “cylinder‐in‐flow” type with a working wire electrode have been investigated. The effective cell volume is 10–40 nl in a system with 0.2–0.4 mm i.d. packed fused‐silica columns. Extra‐column spreading at the optimum elution rate does not exceed 0.005 μl2. The linear range is 103 at a relative standard deviation of 0.009. The low noise level (2–3 pA) facilitates determination of electro‐active substances. The detection limit for catecholamines is of the order of tenths of a femtomole.
Quantitative analysis of phospholipids by HPLC with a light scattering evaporating detector – application to raw materials for cosmetic use
Authors: Becart I. , Chevalier C. , Biesse J. P.
Published: May 2005

A method is described for separation and quantitative analysis of various phospholipids and sphingolipids by high performance liquid chromatography on a silica gel column with a mobile phase consisting of chloroform, methanol, and ammonium hydroxide. Gradient elution is necessary. A study of the light scattering evaporative detector response is presented. The method has been applied to the analysis of phospholipids of a commercial soja lecithin and a pig brain extract.
SFC in analysis of aromatic plants
Authors: Manninen P. , Riekkola M.‐L. , Holm Y. , Hiltunen R.
Published: May 2005

Capillary SFC was applied to the analysis of Some plant volatile oils. The results were compared with those obtained by capillary GC. For thyme oil, SFC without derivatization gave about the same percentage composition of the main compounds as CGC with silylation, thus eliminating one working step. For a complex mixture of peppermint oil or basil oil, SFC seems to give more reliable quantification than CGC, especially for oxygenated compounds. However, the separation efficiency of CGC for monoterpene hydrocarbons was, as expected, much better than that of SFC.
Separation of metal complexes by on‐line coupled LC‐GC
Authors: Lukkari P. , Hannuksela J. , Mattinen M.‐L. , Virolainen M. , Häkkinen Vera M. A. , Riekkola M.‐L.
Published: May 2005

The on‐line coupled LC‐GC technique was applied to the analysis of several metal chelates of N,N‐diethyldithiocarbamic acid. A 10‐port valve interface was used to couple the LC and GC instruments. Conditions during sample transfer into the GC gave fully concurrent solvent evaporation. The chelates investigated were separated with a short apolar fused silica column. LC preseparation was made with cyano or amino phases using a hexane/dichloromethane mixture as eluent. On‐line LC‐GC combination seems to be very suitable for the separation of the metal chelates studied.
Direct resolution of racemic compounds on chiral microbore columns by sub‐ and supercritical fluid chromatography
Authors: Gasparrini Francesco , Misiti Domenico , Villani Claudio
Published: May 2005

Fast resolutions of racemic compounds (sulfoxides, amino alcohols, and α‐methylarylacetic acids derivatives) were achieved on a chiral microbore column using carbon dioxide and a polar methanol/dioxane modifier. The stationary phase used in this study contains the 3,5‐dinitrobenzoyl derivative of R,R(−)‐1,2‐diaminocyclohexane (DACH‐DNB) as the chiral moiety, anchored to a silica gel surface by covalent bonds. Both thermodynamic and kinetic separation performances were improved by using a super‐ or subcritical carbon dioxide mobile phase (SFC, SubFC).
Automatic sugar analysis in the beet industry. Part I: Parameter optimization of a reversed phase HPLC carbohydrate determination
Authors: Herbreteau Bernard , Lafosse Michel , Morin‐Allory Luc , Dreux Michel
Published: May 2005

An evaluation of the most commonly used HPLC system (reversed phase octadecyl sillica gel) was undertaken in order to determine the level of certain carbohydrates in molasses produced in the refining of sugar beet. Chromatographic parameters and purification operations prior to analysis are discussed in order to develop an analytical method permitting automation of sugar determination. A Zorbax ODS column (250 × 9.4 mm), water elution, and light scattering detection allow easy determination of glucose + fructose, sucrose, and raffinose in molasses using an internal standard (maltose).
Capillary gas chromatography of amines with ammonia as carrier gas
Authors: Abdel‐Rehim Mohamed , Hassan Moustapha , Ehrsson Hans
Published: May 2005

The use of ammonia as a carrier gas for the chromatography of aliphatic and aromatic amines has been investigated. As compared to nitrogen, ammonia gave drastically improved peak symmetry and lower capacity factors (k′) for primary and secondary amines on polar (Polyethylene glycol) and medium Polar (methylphenylcyanopropylsilicone) stationary Phases. The effect of ammonia was more Pronounced at low column temperatures. Considerably better detection limits of primary and secondary amines were obtained with ammonia as carrier gas than with nitrogen. No detrimental effects of using ammonia were observed on the gas chromatograph or on the columns over a period of about one year.
Charcoal open tubular traps for the analysis of air and headspace samples
Authors: Grob Konrad , Artho Anna , Frauenfelder Christine , Roth Ives
Published: May 2005

5 cm × 0.3 mm i.d. glass capillary tubes coated with fine charcoal particles are used for the analysis of organic compounds, particularly tri‐ and tetrachloroethylene, benzene, and toluene, in air and headspace samples. Due to their small size, these traps are easy to use with capillary GC. As, e.g. 20 ml of gas can be sucked through this trap in 20 s, it is a simple technique providing high sensitivity; compared to headspace with split injection, sensitivity is increased by a factor exceeding 100. The column effluent is split into FID and ECD in such a way that small as well as large amounts of the chlorinated compounds can be detected.
Programmed cold sample introduction and multidimensional preparative capillary gas chrornatography. Part I: Introduction, design and operation of a new mass flow controlled multidimensional GC system
Authors: Rijks Jacques P. E. M. , Rijks Jacques A.
Published: May 2005

A new design of a mass‐flow controlled multidimensional switching system for capillary gas chromatography is introduced and discussed. Large sample amounts can be introduced with a required input band width onto the first column. A combination of cold sample introduction and successive high speed programmed heating of the injector liner is used for this purpose. The potential of such an approach for selective and fast high resolution separations with series coupled wide bore, thick film columns is emphasized, and illustrated for various concentrations.
Evaluation of a microHPLC system dedictaed to packed capillary column liquid chromatography
Authors: Trisciani Adriano , Andreolini Franca
Published: May 2005

Miniaturization and optimization of the solvent delivery system, mixing device, and detection system for gradient elution at few μl/min is the most important objective of instrumental development in microHPLC using packed capillary columns. Instrumental solutions and evaluation of the performence of a dedicated system for automatic gradient elution with packed capillary columns are reported. Retention time precision shown buy the system results in an RSD of 0.20–0.52% for a PAH model mixture eluted under gradient conditions at few μl/min. Compositional accuracy of gradient profiles is also demonstrated.
Review: Sample preparation of catecholamines and biologically active peptides by solid phase extraction
Authors: Al‐Shammary Fahad J.
Published: May 2005

This paper reviews solid phase extraction as applied to the sample preparation of catecholamines and biologically active peptides. The mechanisms used in solidphase extraction are: non‐polar, polar, ion‐exchange, and covalent.
Chitosan‐based stationary phases in microcolumn liquid chromatography
Authors: Jinno Kiyokatsu , Ogura Satoshi , Takayama Katsumi
Published: May 2005

Two kinds of cross‐linked chitosan beads were evaluated as the stationary phase for microcolumn liquid chromatography. The phase with aminoalkyl substituent can be expected to function similarly to commonly known aminopropyl bonded phases. Separation of PAH with the chitosan phase bearing phenyl group substituents has been accomplished in the gradientelution mode with acetonitrile‐water as the mobile phase. Planarity recognition capability comparable with that of monomeric octadecylsilica phase was observed.
Separation and identification of volatile and non‐volatile compounds of wine by sorbent extraction and capillary gas chromatography
Authors: Gelsomini Nedo , Capozzi Francesco , Faggi Cristina
Published: May 2005

Sorbent extraction technology was used to separate the volatile and non‐volatile components of wine. The extracts were analyzed by capillary gas chromatography.