bluuebunny/crossref_metadata_2025 huggingface dataset:
Methodology for isolating drug metabolites from biological fluids by HPLC
Authors: Overzet F.
Published: May 2005

This article presents a detailed account of the isolation of drug metabolites from bile by reverse‐phase HPLC. The systematic approach is illustrated for the metabolism of butoprozine, a new antianginal drug, in the dog. Separation utilizes isocratic and gradient elution. Detection of the metabolites in. the presence of endogenous bile components is accomplished by very selective radioactivity measurements, by less selective UV (single wavelength) detection, and by much more universal detection modes such as on‐line UV spectroscopy and off‐line mass‐ and nuclear magnetic resonance spectroscopy. The importance of the latter three techniques in purity analysis of isolated metabolites is illustrated.
Investigation of the low temperature effect in reversed phase micro high performance liquid chromatography
Authors: Jinno K. , Ohshima T. , Hirata Y.
Published: May 2005

The low temperature effect has been investigated in reversed phase micro high performance liquid chromatography with various aqueous mobile phase systems by an approach based on enthalpy‐entropy compensation. The compensation temperatures, Tc, were determined for these systems, and the results show that the retention mechanism in a lower temperature column is similar to that in a normal temperature column in the reversed phase mode at mobile phase water contents above 9.8%. At lower water contents, the separation mechanism is different from that in the reversed phase mode, but otherwise very similar to that in the normal phase mode.
Halogenated compound response in an oxygen doped ion mobility detector for capillary gas chromatography
Authors: Baim M. A. , Hill H. H.
Published: May 2005

An ion mobility detector that has been specifically developed for interfacing with capillary gas chromatography is investigated in the negative ion mode. Like the electron capture detector, to which this instrument is closely related, the ion mobility detector shows an enhanced response to low molecular weight halogenated compounds when a small quantity of oxygen is doped into the make‐up gas flow. Under O2 doping conditions, the device can operate in a reactant ion monitoring mode responding universally to compounds capable of capturing thermal electrons and in a tunable selective product ion mode providing increased selectivity over that achieved by the ECD. At an oxygen concentration of 0.5%, minimum detectable amounts as low as 600 femtograms have been realized for carbon tetrachloride. Selectivity of chloro‐ versus bromo‐ compounds is demonstrated using a mixture of p‐dichlorobenzene and p‐dibromobenzene.
Prediction of retention time of phenols in liquid chromatography
Authors: Hanai T. , Hubert J.
Published: May 2005

The chromatographic behavior of phenols in reversed‐phase mode liquid chromatography differs from that of non‐ionic compounds such as alkyl alcohols, alkylbenzenes, halogenated benzenes, polyaromatic hydrocarbons, and aromatic acids. Therefore, the retention times of 61 phenols were measured in a system of an octadecyl bonded silica gel and acetonitrile/water mixtures. The logarithm of the capacity ratio (log k') was found to be a linear function of the hydrophobicity (log P) in acidic acetonitrile/water mixtures. This result was applied to a different octadecyl bonded silica gel. Eight phenols were selected as standard compounds, and their log k' values were measured in 0.05 M phosphoric acid in 10 to 90% acetonitrile/water mixtures. An empirical polynomial relation was obtained between the concentration of acetonitrile and the slope of the log k' vs log P curve. Finally the capacity ratio of all phenols were calculated in given eluents by the equations derived from the measurements of standard compounds and the calculated log P values. The difference between predicted capacity ratios and measured ones was within 10%.
Influence of development distance on resolution in thin‐layer chromatography
Authors: Franke J. P. , Kruyt W. , de Zeeuw R. A.
Published: May 2005

Theoretical equations are given to relate resolution with development distance. Comparative experiments undertaken with quaternary ammonium compounds as test substances and using a selection of basic drugs are presented. As expected, resolution decreases with shorter development distance. However, this effect is less pronounced for compounds with small Rf values and when the spot size at the starting point is kept small. It was also shown that, for correctly assessing resolution in relation to development distance, the amounts of material spotted have to be decreased for shorter development distances.
HPTLC analysis of organotin compounds in preservative solutions and preservative‐treated wood
Authors: Ohlsson Stefan V. , Hintze Wollmal W.
Published: May 2005

A high‐performance thin‐layer chromatographic (HPTLC) method is described for the determination of tributyltin compounds (bis(tri‐n‐butyltin) oxide, TBTO, and tri‐n‐butyltin naphthenate, TBTN) and their degradation products (dibutyltin and monobutyltin compounds). The organotin compounds are extracted from wood with ethanol containing 0.5% (v/v) of hydrochloric acid and the separation of the defferent kinds of organotin compounds is achieved by thin‐layer chromatography. The sample spots are measured using a scanning densitometer after decomposing the organotin compounds to inorganic tin by ultraviolet irradiation and visualization of the spots with pyrocatechol violet.

Applications of the method to detection and quantification of organotin compounds in preservative solutions, in recently impregnated wood, and in wood samples from five‐year‐old window frames are described.
Cutting of glass and fused silica capillaries
Authors: Roeraade J.
Published: May 2005

An investigation of techniques suitable for precision cutting of glass and fused silica capillary tubing has been carried out. Accurate trimming of capillary tubing is important when precision splitters and manifolds have to be made. Techniques employed for cutting optical fibers proved to be useful, and factors affecting the suface quality of the fracture are discussed.

It was found to be difficult to obtain a square cut with a flat surface in the case of fused silica tubing. The best results were obtained when the tubing was scored with the edge of a broken silicon wafer before the fracture was accomplished. This technique allows precision cutting of glass tubing with an outer diameter of 100 μm or less.
Application of capillary gas chromatography to automated on‐line quantitative analysis of solvent vapors
Authors: Radell E. A. , Rea D. F.
Published: May 2005

Solvent vapors in air may be measured with capillary gas chromatographic columns. By using large diameter columns and sample loops of approximately the same internal diameter, the column may be connected directly to the gas sampling valve. This approach eliminates the use of a splitter or cryogenic trapping and allows low levels to be measured. By operating the column at high velocity, column efficiency is sacrificed for increase in speed.
Gas‐liquid chromatographic determination of fenvalerate on woolen cloth
Authors: Simonaitis R. A. , Bry R. E. , Cail R. Spencer
Published: May 2005

A method is described for the determination of fenvalerate (cyano(3‐phenoxyphenyl)methyl 4‐chloro‐α‐(1‐methylethyl)‐benzeneacetate) residues on woolen cloth. The fenvalerate was Soxhlet‐extracted from the treated fabric with acetone for four hours at a reflux rate of six solvent exchanges per hour. The fenvalerate residue was determined by gas‐liquid chromatography with a flame ionization detector. The results were quantitated by comparing integrator counts obtained from extracts of treated samples with those obtained from known standards. The method was sensitive to 0.00054% fenvalerate by weight. Recoveries from fabric treated with 0.00054% to 0.215% averaged 94.8%. The response of the detector was linear over a 400‐fold range of fenvalerate concentrations.
Behavior of fused silica capillaries subjected to gamma radiation. Part 1: Chromatographic performance
Authors: Hubball J. A. , DiMauro P. , Barry E. F. , Chabot G. E.
Published: May 2005

Fused silica capillaries deactivated with D4 and coated with OV‐1 were subjected to cobalt‐60 gamma radiation in order to elucidate the effect of incident radiation on column performance. The chromatographic performance of these open tubular columns in which OV‐1 was polymerized in situ was found to be dependent on the dosage of radiation and was evaluated before and after the irradiated columns were rinsed with solvent. Of the radiation dosages employed, 3 MRad produced superior chromatographic performance coupled with very favorable residual surface activity.
Residue analysis of organophosphorus pesticides in food with two‐dimensional gas chromatography using capillary columns and flame photometric detection
Authors: Stan H.‐J , Mrowetz D.
Published: May 2005

Two‐dimensional gas chromatography with two capillary columns of different polarity (SP 2100 and OV 225) is used for pesticide residue analysis in food samples. By means of “live chromatography” applying pneumatic switching technique according to Deans, unequivocal identification of 57 organophosphorus pesticides in food samples is achieved at trace concentrations. The instrument is equipped with only one injection port and one flame photometric detector. On‐line data processing is very helpful, especially in calibration and checking the system's reliability with the multitude of test compounds. The complete pesticide residue analysis including clean‐up of about six food samples can be completed by one person in 8 hours.
A method of calculating the specific retention volumes of substances from their retention indices and specific retention volumes of n‐alkanes
Authors: Golovnya R. V. , Grigoryeva D. N.
Published: May 2005

The choice of stationary phase for gas chromatography is dictated by the nature of the analytes. Polarity and selectivity are known to play an important role. This paper suggests equations for calculation of specific retention volumes of any compounds from their retention indices.
Behaviour of fused silica capillaries subjected to gamma radiation. Part 2: Physical aspects
Authors: Barry E. F. , Chabot G. E. , Ferioli P. , Hubball J. A. , Rand E. M.
Published: May 2005

Five commercial varieties of uncoated fused silica capillary tubing used in high resolution gas chromatography were subjected to cobalt‐60 gamma radiation. The advantages and superior performance of fused silica open tubular columns coated with OV‐1 and subsequently immobilized or crosslinked in situ by radiation is reported in a previous paper in this Journal; however, in this investigation a loss in flexibility of irradiated capillaries was also noted. Quantitative measurements on flexibility were performed on specimens of irradiated fused silica capillaries, indicating that changes do indeed occur upon irradiation. Scanning electron micrographs also illustrate slight deterioration of the outer protective polyimide coating. Most surprisingly, it was also established that a variation does exist in the flexibility of the commercially available raw material studied.
Ion‐pair chromatography with UV absorbing counterions on reversed‐phase layers. Part 1: Chromatography with hydroxynaphthalenesulfonic acids
Authors: Volkmann D.
Published: May 2005

The results of ion‐pair chromatography with UV‐absorbing counterions are described. Hydroxynaphthalenesulfonic acids are used as ion pair formers, and alkaloids as test samples. The separations are performed on silanized silica gel from Merck and KC18F plates from Whatman. The influence of the counterion on the Rf‐value is demonstrated. Some alkaloids exhibit characteristic fluorescence as ion pairs.
Comparison of gas chromatographic and gas chromatographic/mass spectrometric techniques for the analysis of TNT and related nitroaromatic compounds
Authors: Weinberg D. S. , Hsu J. P.
Published: May 2005

The use of capillary column gas chromatography and gas chromatography/mass spectrometry for the analysis of a series of standard solutions (0.1 to 10 μg/ml) of 2,4,6‐trinitrotoluene (TNT) and eight other nitroaromatic components was evaluated. The techniques included gas chromatography with electron capture detection (GC/ECD), full scan and selected ion monitoring gas chromatography/mass spectrometry with electron impact ionization (EI/FS and EI/SIM), full scan and selected ion monitoring gas chromatography/mass spectrometry with positive ion chemical ionization using methane reagent gas (PICI/FS and PICI/SIM), and full scan and selected ion monitoring gas chromatography/mass spectrometry with negative ion chemical ionization using methane reagent gas (NICI/FS and NICI/SIM). The performance of the techniques was comapared by determining the linear response range, precision, and detection limits of the analyses.
A polar glass capillary column for residue work
Authors: Rinderknecht F. , Wenger B.
Published: May 2005

Polydiethylene glycol adipate (DEGA) has been successfully used as stationary phase for residue analysis by glass capillary gas chromatography. A specially stabilized version of the phase yields a good polar column which is stable up to 250°C when used in temperature programmed cycles. The paper lists 90 pesticides that have been successfully chromatographed in ng quantities on a DEGA column.
An investigation of microbore reverse‐phase columns containing 3 μm packing materials
Authors: Vadukul N. K. , Loscombe C. R.
Published: May 2005

A procedure for packing 15 cm × 1 mm id reverse‐phase microbore columns with 3 μm silicas obtained from different manufacturers is described. The speed of analysis and detection limits are compared to those obtained with a 50 cm × 1 mm id column packed with 10 μm ODS. The effect of detector time constant on the system, and flow rates on column efficiency are also examined.
Flavor analysis by HRGC/FT‐IR: Cherimoya (Annona cherimolia, mill.) fruit volatiles
Authors: Herres W. , Idstein H. , Schreier P.
Published: May 2005

The volatiles of fresh cherimoya (Annona cherimolia, Mill.) fruit pulp were separated by combined high‐vacuum distillationliquid/liquid extraction (pentane/dichloromethane 2+1). After preseparation by liquid chromatography on silica gel three fractions (I‐III) were obtained by eluting with pentane (I), pentane/diethyl ether (9+1) (II), and diethyl ether (III), and fractions II and III were subjected to HRGC/FT‐IR analysis. 26 volatile compounds comprising nearly all the main components (range, 10–300 μg/kg fruit pulp) were identified by this technique for the first time in cherimoya fruit.
Analysis of coal tar and petroleum pitches by computerized pattern recognition
Authors: Moncur J. G. , Bradshaw W. G.
Published: May 2005

Pyrolysis gas chromatography (P/GC) has been successful in differentiating coal tar pitches which are used in the manufacture of high temperature graphite materials [1,2]. In the present study, coal tar and petroleum pitches received from five suppliers were readily differentiated using three distinct methods of polymer analysis: dynamic headspace and pyrolysis gas chromatography mass spectrometry (DH/GC/MS and P/GC/MS, [3]), and pyrolysis mass spectrometry (P/MS, [4,5]). All of these methods are appropriate for the analysis and pattern recognition study of coal and petroleum products; however, methods which incorporate GC usually necessitate long analysis times and are subject to problems associated with gas chromatographic reproducibility (e.g. active sites [6], and nonconstant retention times). As a fingerprint analysis method, P/MS is rapid and ideally suited to computerized pattern recognition study of pitches due to the simple format of P/MS data (computer tabulation of normalized intensities versus masses); whereas, in the present study, the normalized peak area versus retention time date from DH/GC/MS and P/GC/MS analyses were not suitable for direct input to a computerized pattern recognition analysis program, (due to non‐constant retention times and improper data format). One limitation is that P/MS does not provide positive identification of thermally evolved products (as can DH/GC/MS and P/GC/MS) due to the complexity of the spectra of a mixture of compounds produced by P/MS. Within the limits of the commercial instrumentation and computer programs used in this study, a combination of all three techniques provided the greatest capability for the differentiation of the five coal tar and petroleum based pitches studied.
Influence of injection systems on the gas chromatographic analysis of oxygenated dibenzothiophenes
Authors: Vignier V. , Berthou F. , Picart D.
Published: May 2005

Analytical methods are described for identification and monitoring of the oxygenated metabolites of dibenzothiophene. Since such compounds are thermolabile, GC analysis is seen to be hardly feasible with conventional injectors such as all‐glass moving needle or splitless injectors. Only on‐column injection gives no degradation products. In addition, reversed‐phase HPLC is particularly suitable for the analysis of the sulfone or sulfoxides of dibenzothiophenes.
Polarizable biphenyl polysiloxane stationary phase for capillary column gas chromatography
Authors: Kuei J. C. , Shelton J. I. , Castle L. W. , Kong R. C. , Richter B. E. , Bradshaw J. S. , Lee M. L.
Published: May 2005

A crosslinkable biphenylmethylpolysiloxane stationary phase was synthesized for capillary column gas chromatography and compared with methyl, phenyl, and cyanopropyl polysiloxane stationary phases for the separation of isomeric polycyclic aromatic compounds. While the new phase gave similar separations of nonpolar isomers when compared to the nonpolar phases, separations of polar isomers were greatly improved because of the induced polarity of the biphenyl group of the stationary phase by the solute molecules. This polarizable stationary phase offers a unique selectivity which is not available in other stationary phases.
A unique reversal of elution order during direct enantiomeric resolution of amide derivatives of 1‐phenyl‐2‐aminopropane by high performance liquid chromatography on chiral stationary phases
Authors: Doyle T. D. , Wainer I. W.
Published: May 2005

Enantiomeric amide derivatives of (S)‐ and (R)‐1‐phenyl‐2‐aminopropane (dextro‐ and levoamphetamine, respectively) were resolved by high performance liquid chromatography on commercially available ionically and covalently bonded chiral stationary phases ((R)‐N‐(3,5‐dinitrobenzoyl)phenylglycine). Ten enantiomeric amide pairs were synthesized and chromatographed on the columns by using a mobile phase of hexane‐isopropanol (97 : 3), a flow rate of 2 ml/min, and a column temperature of 20°C. The (R)‐isomer of all 10 amides eluted first on the covalent column as did the (R)‐isomer of nine derivatives on the ionic column. however, the 3,5‐dinitrobenzoyl amide of (S)‐ amphetamine eluted before the (R)‐isomer on the ionic column. This reversal in enantiomeric elution order reveals the complexity of the interactions occurring on these columns and emphasizes the hazards of relying on observed elution order as an a priori indication of absolute configuration.
The stationary phase capacity concept in elution liquid chromatography
Authors: Gareli P. , Semerdjian L. , Caude M. , Rosset R.
Published: May 2005

The stationary‐phase capacity concepts derived from linear capacity are discussed in connection with the needs of analytical, trace enrichment analysis and preparative chromatography and shown to be unsuited to them. A new concept based on stationary‐phase saturation and called “available capacity” is proposed. It generalizes the ion‐exchanger exchange capacity to adsorption and partition chromatography when the sampling solvent is the mobile phase.

In linear elution chromatography the available capacity is proportional to the solute concentration Co and to the analytical capacity factor k′ for given Co and k′ values, it is independent of the nature of the solute. Furthermore, when both the concentrations and the analytical capacity factors (practically, for Co ≥ 1 M and k′ ≥ 10, respectively) are high, the available capacity reaches a value roughly independent of Co and k′, called “maximum available capacity” and related only to the number of sites available on the stationary phase. Numerous measurements were made in ion‐exchange, adsorption, and reversed‐phase chromatography. For solutes having a single polar functional group interacting with the stationary phase, the orders of magnitude of the maximum available capacity are 1.2 mmole g−1 for a classical silica gel (Partisil 5 μm, 400m−2 g−1 with a water content of 2.7%); 1.8 mmole g−1 for the Lichroprep RP 8 octyl bonded silica (11.6% carbon content); 3.8 mmole g−1 for an anion exchanger resin of Dowex type.
Migration of the mobile phase and zones of separated substances in flat‐bed chromatography
Authors: Gimpelson V. G. , Berezkin V. G.
Published: May 2005

It is proposed to extend the area of application of circular separation of substances in flat‐bed chromatography by a wider use of its intermedial modifications. Equations for calculating the basic parameters of migration of the mobile phase and zones of separated substances are given. The known equations are shown to be particular cases of the ones proposed.
Threshold temperatures for solute mobility. Their determination and effect on programmed temperature gas chromatographic separations
Authors: Saxton W. L.
Published: May 2005

The threshold temperature for solute mobility is defined as that temperature at which a solute band, which was initially cold trapped at the head of the column, begins moving through the column. It is shown that the separation of compounds by programmed temperature gas Chromatography (PTGC) occurs primarily at the head of the column as a result of differences in threshold temperatures. Additional column length beyoud that needed to trap the compounds improves resolution, primarily by delaying emergence (while maintaining the temperature and time spacing) thus allowing the column temperature to rise, the solute terminal velocities to increase, and narrower peak widths to be recorded. For maximum resolution in minimum analysis time, the initial temperature must be at or below the threshold temperature of the most volatile compound in the mixture to be separated.

Three methods for determining threshold temperatures are presented.
Determination of flurazepam and its hydroxyethyl and dealkyl metabolites by some packed and capillary ECD‐GLC methods: Application to pharmacokinetic studies
Authors: Coassolo Ph. , Aubert C. , Cano J. P.
Published: May 2005

A sensitive gas‐liquid chromatographic assay was developed for plasma determinations of flurazepam (F), N1‐desalkylflurazepam (DF), and N1‐hydroxyethylflurazepam (HF). The internal standards used were delorazepam for F and DF and 1 ã‐hydroxymidazolam for HF. Following extraction and derivatization for HF, these compounds were analyzed by ECD‐GLC, using either glass packed columns (poly A 103 for F and DF, OV 225 for HF) or CP‐Sil 5 capillary columns for DF and HF. The detection limit of the packed‐column assay was approximately 3ng/ml for HF and DF, and 5ng/ml for F; with capillary GLC analysis, the sensitivity limit for HF and DF was lower than 1 ng/ml. These methods were used for pharmacokinetic investigations after i. v. administration of these compunds.
Clean‐up of polynuclear aromatic hydrocarbons and 3‐ring azaarenes and their GC‐analysis on whisker‐walled open tubular columns
Authors: Spitzer T. , Dannecker W.
Published: May 2005

A modified clean‐up of polynuclear aromatic (PNA) hydrocarbons on XAD‐2 is described. n‐Alkanes (C16C28) are separated quantitatively from the PNA hydrocarbons and are eluted in one fraction. The distribution of 17 PNA hydrocarbons and four of their alkyl derivatives, two S‐heterocyclic compounds and two azaarenes between the different fractions is reported. Azaarenes containing three rings are separated from PNA hydrocarbons and S‐heterocyclic compounds. Whisker‐walled open tubular columns coated with OV‐215 and OV‐25 were used in the separation of isomeric azaarenes and in PNA hydrocarbon profile analysis, respectively. The preparation of such columns is described in detail. Rinsing of capillary columns with cold, concentrated HCI after whisker growth removes much larger amounts of boron and sodium than subsequent leaching with HCI at 180°C. Whisker‐walled open tubular columns are successfully applied to the characterization of isomeric benzofluoranthenes and other PNA hydrocarbons isolated from air particulate matter.
Increased speed of steroid analysis by capillary GC and GC‐MS; effects of sample pretreatment and sample introdution
Authors: Curvers J. , Maris F. , Cramers C. , Schutjes C. , Rijks J.
Published: May 2005

Quantitative analysis of steroids and their metabolites in urine samples calls for increased speed of sample clean‐up, of the derivatization procedure, and of separation. A fast procedure for sample pretreatment, which can be performed within 8 hours, is introduced and evaluated. It is shown that use of fast pretreatment in combination with narrow bore columns, which are compatible with existing instrumentation, can considerably increase, laboratory throughput. The effect of different sample introduction techniques (e.g. splitless, on‐column, and moving needle) on column efficiency and resolution is demonstrated and discussed.
HPLC of nucleotides. II. General methods and their development for analysis and preparative separation. An approach to selectivity control
Authors: Wulfson A. N. , Yakimov S. A.
Published: May 2005

In order to develop efficient separation methods for nucleotides according to their size and heterocyclic composition, the application of ion‐exchange, reverse‐phase, and normal‐phase adsorption HPLC has been studied. The comparative investigation of retention power and selectivity of various packings (non‐polar bonded‐phase and amino silicas) in relation to nucleotide length and composition yields data which enable suitable packings to be selected and a method of preparing the new packing for a particular separation problem to be formulated. Thus a new anion exchanger with high selectivity and dynamic mass transfer has been prepared for fractionation of large oligonucleotides. The effect of the eluent pH and composition (organic modifier, salt) on retention, selectivity, and resolution in ion‐exchange and reverse‐phase HPLC has been studied. The optimum separation conditions comprise elution with oppositely directed gradients of the salt and the modifier, use of a precolumn packing that provides the best protection for the main column without loss of its efficiency, and the optimum gradient program for the desired retention of the component of interest. The relation between loading and sample concentration has been studied and the system for gradient elution improved. Our work shows that two‐dimensional separation is the most reliable and informative method for preparation of homogeneous oligonucleotides. The hydrophobic‐pair ion‐exchange mechanism is proposed for ion‐pair chromatography. Protected and partially deblocked oligonucleotides, chemically synthesized for genetic engineering studies, have been separated with high selectivity by adsorption (normal‐phase) HPLC which is efficient for gradient elution with isohydric eluents. The analysis of a monomeric composition of nano‐(pico‐) molar amounts of oligonucleotides has been developed; the procedure involves microcolumn digestion of the oligonucleotides with immobilized enzymes followed by microcolumn separation of the nucleoside‐mononucleotide mixture. Also, a new slurry method for packing stable HPLC columns with a tightly consolidated, nonshrinkable bed of particles has been developed.
Analysis of mutagenic amino acid pyrolyzates with a fused silica capillary column
Authors: Schunk H. , Hayashi T. , Shibamoto T.
Published: May 2005

In this study, application of a fused silica capillary column for analysis of major mutagenic heterocyclic compounds found in cooked foods was investigated.
Preparative HPLC. Part 1: A comparison of three types of equipment for the purification of steroids
Authors: Matlin S. A. , Chan L.
Published: May 2005

Two commercial preparative liquid chromatographs have been evaluated for gram‐scale purification of steroid esters. The Jobin‐Yvon and Waters chromatographs both allow fast separations. Neither system has a high intrinsic column efficiency, but the resolving power of the Waters system can be increased by the use of recycle. A laboratory‐assembled preparative liquid chromatograph is described which is economical both in construction and operation, versatile, and considerably more efficient than the two commercial alternatives for single runs on up to a gram scale.
Immobilization of stationary phase films by gamma radiation. Part 1. Nonpolar phases, regular and thick‐film capillaries
Authors: Vigh Gy. , Etler O.
Published: May 2005

Borosilicate glass capillaries, silylated and coated with OV‐1 or SE‐54, were irradiated by a 60Co gamma source. The effect of radiation on chromatographic performance was determined for a series of dosages and was evaluated before and after rinsing with solvent. Results for both regular and thick films were obtained.
Reaction gas chromatography/mass spectrometry. Part IX: Post‐column hydrodesulfurization in capillary GC/MS as an aid in structure elucidation of cyclic sulfides within mixtures
Authors: Mikaya A. I. , Trusova E. A. , Zaikin V. G. , Zegel'man L. A. , Urin A. B. , Volinsky N. P.
Published: May 2005

This article describes a method that assists in structure determination of cyclic sulfides mixtures by GC/MS. The method involves the use of a gas‐phase hydrodesulfurization microreactor (AP‐56 catalyst, reaction temperture 300‐315°C, hydrogen as a carrier and reagent gas) located between the capillary column (OV‐17) and the mass spectrometer. The presence of a microreactor in such a position does not essentially affect the chromatographic separation achieved by using the capillary column. Combined analysis of the mass spectra registered for the original sulfides and the hydrodesulfurization products permits the structure determination of each effluent to be made more reliably. This is illustrated by the investigation of a reaction mixture containing the structural and geometric isomers of methyl‐substituted thiabicyclononanes.
Identification and quantification of diesel fuel components derived from off‐shore drilling operation discharges
Authors: Hiatt M. H. , Jones T. L.
Published: May 2005

A GC/MS technique that provides quantitative and qualitative information on diesel fuel components in drilling muds is described. Several low molecular mass aromatic components of diesel fuel are identified as indicators of diesel fuel. The presence and relative concentration of these indicators is used to identify diesel fuel contamination. This information can be used to approximate the amount of diesel fuel contamination in off‐shore drilling discharges.
In‐product jojoba determination using anticircular high performance thin layer chromatography
Authors: Studer A. , Traitler H.
Published: May 2005

Cosmetic creams were analyzed for their content of jojoba wax and shea fat using anticircular HPTLC, a fast, precise, and reliable method. After optimization of the solvent system (petrol ether/diethyl ether) for the separation of jojoba wax and shea fat, the spots were visualized with phosphomolybdic acid by the “dip‐in” technique, subsequently heated, and finally recorded by scanning with a densitometer at 546 nm. Results showed that one particular concentration range gives an optimum correlation between calibration curves and sample evaluations.
Analysis of gases containing inorganic and organic compounds using a combination of a thick‐film capillary column and a packed adsorption column
Authors: Coleman P. , Ettre L. S.
Published: May 2005

A gas chromatographic system consisting of one multiport valve, two (hot‐wire and flame‐ionization) detectors and two analytical columns (one thick‐film capillary and one packed adsorption column) is used for the analysis of gas samples containing a number of inorganic compounds (hydrogen, argon, oxygen, nitrogen, carbon monoxide, and carbon dioxide) and organic compounds. Examples include samples containing hydrocarbons up to n‐nonane and benzene and toluene. The system also permits the analysis of more complicated samples containing, for example, alcohols, in addition to hydrocarbons.
Thermospray high performance liquid chromatographic/mass spectrometric analysis of some fusarium mycotoxins
Authors: Voyksner R. D. , Hagler W. M. , Tyczkowska K. , Haney C. A.
Published: May 2005

Thermospray high performance liquid chromatography/mass spectrometry (TSP HPLC/MS) was used to analyze five Fusarium mycotoxins in porcine plasma and urine. Four cytotoxic trichothecene mycotoxins, T‐2 toxin, HT‐2 toxin, diacetoxyscirpenol (DAS), deoxynivalenol (DON), T2 tetraol, and the fungal estrogen zearalenone (F‐2 toxin) were analyzed. The thermospray mass spectrum contained molecular weight information with few, if any, fragment signals. Detection limits ranging from 1 to 10 ng of mycotoxin injected onto the HPLC column were obtained using selected ion monitoring (SIM) HPLC/MS. Neither the plasma nor the urine matrix interfered with TSP HPLC/MS analysis of these mycotoxins and no sample derivatization was necessary for the analysis. The TSP HPLC/MS technique appears to be ideal for very sensitive analysis of mycotoxins in biological samples.
Free release static coating of glass capillary columns; rapid coating at lower temperatures and elevated pressures
Authors: Xu B. , Vermeulen N. P. E.
Published: May 2005

The coating speed upon static coating of glass capillary columans was evaluated in terms of inner diameter and length of the column, viscosity and pressure of solvent vapor, etc. From the equation obtained it can be shown that a smaller diameter of a microbore column restricts solvent vapor transfer to the orifice of the column drastically. To compensate for this restriction, a higher pressure at the meniscus is needed. As an alternative to using a higher coating temperature, application of more volatile solvents such as n‐butane and isobutane is proposed. Several glass capillary columns (130 μm i.d.) were coated with SE‐54 dissolved inpentane‐acetone mixed with n‐butane or isobutane and the column performances were evaluated. Selection of these solvents permitted free release static coating of ca. 100 μm columns at lower or even ambient temperatures and they were equally suitable as commonly applied solvents (e.g. pentane) to coat highly efficient columns.
Disengaging solutes in shale‐ and petroleum‐derived jet fuels by altering GC programmed temperature rates
Authors: Hayes P. C. , Pitzer E. W.
Published: May 2005

Overlapping chromatographic peaks of components from different hydrocarbon classes can be disengaged by exploiting their shifts in relative retention behavior with changes in linear rates of programmed temperature. Many co‐eluting species in complex chromatograms of shale‐ and petroleum‐derived jet fuels can be resolved without varying stationary phase, column length, or initial column temperature.

Retention indices were simultaneously determined on two bonded‐phase, fused silica capillary columns of slightly different polarities at three different linear programmed temperature rates. For certain hydrocarbon types, no change in index values was observed with an alteration in programming rate. However, the indices of other hydrocarbon classes shifted uniformly with programmed temperature rates on each of the two stationary phases. When applied, this phenomenon could help resolve coeluting members of different or even the same hydrocarbon type and elucidate their probable structure. The overall precision of the retention indices, i.e., the mean standard deviation at the 95% confidence levels, was less than ±0.13 for either column at any of the three programming rates. Since the above technique is automated, it could also be a useful screening tool to search for specific hydrocarbons in a myriad of unknown components of a complex hydrocarbon mixture.
Analysis of toxic anthraquinones and related compounds with a fused silica capillary column
Authors: Lewis D. C. , Shibamoto T.
Published: May 2005

In this study, application of a fused silica capillary column for analysis of toxic anthraquinones and related compounds found in plants was investigated.
Assessment of the results from data processing systems using a digital chromatogram simulator
Authors: Hunt R. J.
Published: May 2005

A digital chromatogram simulator has been used to evaluate the performance of data handling systems. The simulator can synthesize chromatograms with any desired shape from a library of peaks based on real peak shapes. Once generated, the chromatograms can be reproduced exactly any number of times.

The algorithms used in data handling systems have a significant effect on the results they produce. An object of this work was to examine how well the true size of a peak was reported when the peak was detected overlapping with other peaks. A series of experiments was therefore performed in which peaks were overlapped by different amounts and in different situations. The reported results from the data systems were compared with the results which would have been reported had the peaks been fully resolved. A significant difference was found between the overlap results and the fully resolved results, which did not have a linear relationship with the parameters tested.

The chromatogram simulator was found to be a powerful tool in assessing the performance of the data systems. It offers a valuable means of evaluating the quality of the results produced by these systems.
Deactivation of fused silica capillary columns with phenylhydrosiloxanes
Authors: Markides K. E. , Tarbet B. J. , Woolley C. L. , Schregenberger C. M. , Bradshaw J. S. , Lee M. L. , Bartle K. D.
Published: May 2005

In this work, an investigation of new organosilicon hydride reagents with phenyl functional groups for deactivation and surface modification of fused silica capillary columns is described. Different reagents were tested for their ability to deactivate the fused silica surface, and actual critical surface tension measurements were made using the capillary rise method. The deactivation procedure required lower optimum temperatures than conventional methods. Deactivated capillaries and coated capillary columns were prepared and tested for reproducibility, efficiency, and surface inertness towards basic and acidic compounds at the low nanogram level.
Temperature dependence of the resolution of diastereomeric isoprenoids in capillary GC. Experiments with 50 μm, 100 μm, and 250 μm i.d. Columns
Authors: Proot M. , David F. , Sandra P. , Verzele M.
Published: May 2005

The resolution of the diastereoisomers of norpristane, pristane, and phytane was studied as a function of the column internal diameter and/or the residence time of the compounds in the column. Increasing the residence time in the column by operating the column at a lower temperature program rate enhances the resolution more than reducing the internal diameter of the column. Practical experience with ultra narrow bore columns is also presented.
High resolution gas chromatographic determination of permanent gases with a helium ionization detector
Authors: Verga G. R.
Published: May 2005

The capability of the helium ionization detector (HID) to operate in connection with capillary columns for trace gas analyses has been evaluated. Two different capillary columns were considered: a PLOT fused silica column with molecular sleve and a thick film WCOT glass column with PS‐255. The determination of trace impurities in gases can be achieved with evident advantages over classical adsorption columns, even using a split injection system. Direct on‐column injections also have been investigated with promising results.
Topical administration of ibuprofen in man. Simultaneous determination of the drug and its metabolites in urine by high resolution gas chromatography
Authors: Giachetti C. , Zanolo G. , Canali S.
Published: May 2005

A selective and sensitive high resolution gas chromatography assay for simultaneous determination of Ibuprofen and its major metabolites in urine is described. Biological samples were collected from healthy volunteers after a single topical administration of the drug in gel form. The chromatographic system, developed on a WCOT OV‐1 glass capillary column, ensured a clear separation of Ibuprofen and its metabolites and their quantitative evaluation.
Variation of tube diameter and film thickness of capillary columns
Authors: Ettre L. S.
Published: May 2005

This paper briefly surveys three important considerations related to the tube diameter and film thickness. These are the interrelationship of these two parameters through the phase ratio, the different meanings of the term “efficiency”, and the influence of film thickness and tube diameter on sample capacity. Comparative examples are given for columns having different diameters and film thicknesses.
Characterization of silicone phases by alkaline hydrolysis and CGC analysis
Authors: Temmerman I. , Sandra P. , Verzele M.
Published: May 2005

A simple way to elucidate the functional group substitution on silicone chains is presented. The polymer is decomposed into its monomers by alkaline hydrolysis. These monomers are converted into trimethylsilyl derivatives, which are then analyzed and identified by capillary gas chromatography/mass spectrometry.
Solvent gradient elution in micro HPLC
Authors: Ishii D. , Hashimoto Y. , Asai H. , Watanabe K. , Takeuchi T.
Published: May 2005

A simple gradient method for capillary column and micro high performance liquid chromatography using either single or multiple mixing chambers is presented. The gradient profile is dependent on the number of the mixing chambers. This system permits solvent gradient elution at flow rates less than 10 μl/min with satisfactory reproducibility.
Retention in capillary supercritical fluid chromatography
Authors: Chester T. L. , Innis D. P.
Published: May 2005

Supercritical fluid chromatography (SFC) sometimes exhibits GC‐like behavior and sometimes LC‐like behavior, depending on conditions. However, it is not always clear whether one of these types of behavior, or a combination, operates for a particular set of conditions for every solute in a mixture. For example, some components may be partitioned mostly by their vapor pressures, while others, in the same mixture, are partitioned predominantly by solvent‐like properties of the mobile phase.

Plots of retetion (as log of the capacity factor) vs. reciprocal temperature at constant pressure reveal a clear change in the character of the separation of well‐behaved solutes. A thermodynamic explanation of the observed behavior is given, based on the assumption that partitioning is controlled by the heats of solution of solute in the mobile and stationary phases. A model of SFC retention as it deviates from pure‐GC behavior on the same column is presented.
Quantitation in capillary gas chromatography with emphasis on the problems of sample introduction
Authors: Schomburg G. , Häusig U. , Husmann H.
Published: May 2005

Sampling techniques for practical quantitative capillary GC have to meet certain principal requirements. Both the absolute and the relative peak areas (e.g. column loads) must be reproducible with high precision and at high accuracy; discrimination of certain constituents according to their volatility should not take place on sampling. On the basis of systematic studies, the three most reliable sampling techniques used for GC analyses with the aim of achieving precise and accurate quantitative data proved to be the following: On‐column, injection, splitless PTV injection, and an optimized version of split sampling called “cooled needle split” injection. The on‐column technique can be optimized by using precolumns with wider internal diameters and without stationary phase coatings to overcome the problems of large liquid sampling volumes and for automation. The PTV technique should only be used in the splitless mode because discrimination cannot be suppressed completely with the split mode. All three of the techniques can be operated automatically, either to avoid “human interference”, i.e. to improve precision or for unattended operation to save man‐power.
Application of the “cooled needle” technique to split and splitless sampling onto capillary columns
Authors: Schomburg G. , Häusig U.
Published: May 2005

Cooled needle sampling using syringes was applied to splitless injection and to simulated distillation analyses. Slight changes of the construction of the previous device are also described. The changes concern the temperature profile within the injector and especially the vaporization insert. Even with the low carrier gas flow through the injector during splitless injection, discrimination by component volatility can be avoided. Precision and accuracy of simulated distillation data obtained with split sampling also can be improved by the cooled needle technique.
Dramatic selectivity changes on carrier gas flow change in a series‐coupled GC capillary tandem
Authors: Kaiser R. E. , Rieder R. I. , Leming Lin , Blomberg L. , Kusz P.
Published: May 2005

We describe the polarity of selectivity of a GC separation system in terms of Retention Index data. In a series‐coupled capillary system having stationary phases of differing polarity even slight (independent!) carrier gas flow changes in one part of the capillary series result in a dramatic change of selectivity. “Dramatic” is a relative term! Using a simple electronically controlled flow changing device we found retention index changes of several hundred units for polar test compounds such as phenols on a SE30/Carbowax tandem. This means: The classical theoretical model for understanding retention (and selectivity) in chromatography must be corrected. We propose a very simple approach involving addition of the expression RESIDENCE TIME to the chromatographic vocabulary. Instead of using flow resistors, one can just add a pressure regulator to the coupling point. A powerful analytical concept is now in easy reach.
Analysis of petroleum fractions by on‐line micro HPLC‐HRGC coupling, involving increased efficiency in using retention gaps by partially concurrent solvent evaporation
Authors: Munari F. , Trisciani A. , Mapelli G. , Trestianu S. , Grob K. , Colin J. M.
Published: May 2005

Two‐dimensional chromatography of gasoline by on‐line coupled HPLC‐HRGC, as described in this paper, allows separate GC analysis of paraffins and aromatics. The GC system contains a retention gap of only 10 m length for introducing HPLC fractions of 100 μl volume. This becomes possible through evaporation of part of the solvent during introduction of the HPLC eluent. This “partially concurrent solvent evaporation” technique allows transfer of large volumes of HPLC eluent into relatively short retention gaps, maintaining the full efficiency of the solvent effects in reconcentrating the bands of the early eluted solutes.