bluuebunny/crossref_metadata_2025_split huggingface dataset:
A novel focusing injection technique for chemiluminescent detection of volatile sulfur compounds separated by HRGC
Authors: Burdge Julia R. , Cai Zhong‐tao , Papillon Jay , Farwell Sherry 
Published: May 2005

AbstractA one meter stainless steel capillary column coated with a 20μm film of polydimethylsiloxane was used to replace the Teflon gas sampling loop of a HRGC – flameless SCD system. This column trap was equilibrated with the gaseous sample and then purged with carrier gas while being sequentially, resistively heated in ten 10 cm sections. The sequential heating of the 10cm sections was timed such that the velocity of the moving heated zone was approximately the same as the velocity of the carrier gas. The thick stationary phase film served to retard the front end of the injection band while the ballistic heating accelerated the back end. The net result was focusing of the injection, which gave rise to a narrower injection profile than that obtained with the original Teflon loop.
Chromatographic properties of zirconia‐based stationary phases for ion exchange chromatography having surface bound cationic functions
Authors: Yu Jim , Rassi Ziad El 
Published: May 2005

AbstractA series of non‐porous, microspherical zirconia‐based stationary phases with surface bound cationic functions have been introduced and evaluated in ion exchange chromatography of proteins and small acidic solutes. Different surface modification procedures were evaluated in the covalent attachment of weak, strong or hybrid anion exchange moieties on the surface of non‐porous zirconia micropar‐ticles. N,N‐Diethylaminoethanol (DEAE) was used as the weak anion exchange ligand while glycidyltrimethylammonium chloride, which was covalently attached to poly(vinyl alcohol) layer (PVAN) on the zirconia surface, constituted the strong anion exchange moiety. Partially quaternarized poly(ethyleneimine) hydroxyethylated (PEI) was used as the hybrid type of anion exchange coating. DEAE‐zir‐conia microparticles acted as purely cation exchange stationary phases toward basic proteins indicating the predominance of electron donor‐electron acceptor interaction (EDA) with surface exposed zirconium sites as well as cation exchange mechanism via electrostatic interaction with unreacted and unshielded hydroxyl groups. PVAN‐zirconia stationary phase exhibited anion exchange chromatographic properties toward acidic proteins, but EDA interaction has stayed as an important contributor to solute retention despite the presence of a relatively thick layer of poly(vinyl alcohol) on the surface of the zirconia particles. The modification of zirconia surface with partially quaternarized PEI proved to be the most effective approach to minimize Lewis acidic metallic properties of the support. In fact, PEI‐zirconia stationary phase operated as an anion exchanger toward acidic proteins and other small acidic solutes.
Simultaneous HPLC determination of phenylurea herbicides and their corresponding anilines in water after on‐line preconcentration
Authors: Hatrík Štefan , Lehotay Jozef , Tekel' Jozef 
Published: May 2005

AbstractOn‐line preconcentration on a short C18 column, prior to HPLC with UV and electrochemical detection, has been used for determination of some phenylurea herbicides and their possible degradation products, substituted anilines, in water samples. With electrochemical detection the detection limit at a signal‐to‐noise ratio of 3 was 5 ppt for 4‐chloroaniline and 4‐bromoaniline and 7 ppt for 3,4‐dichloroaniline; with UV detection the detection limit was ca 300 ppt for all analytes.
Reversed phase HPLC determination of titanium(IV) and iron(III) with sodium 1,2‐dihydroxybenzene‐3,5‐disulfonic acid
Authors: Nagaosa Yukio , Segawa Shin‐ichi 
Published: May 2005

AbstractA highly sensitive method has been developed for the determination of titanium(IV) and iron(III) by ion‐pair reversed phase liquid chromatography using sodium 1,2‐dihydroxybenzene‐3,5‐disulfonic acid (Tiron) as a precolumn chelating reagent. The metal ‐ Tiron chelates were separated on a C18 (ODS) column; the mobile phase was a 2:8 (v/v) mixture of acetonitrile and acetate buffer (0.04 mol/L, pH 6.2) containing 2.0 × 10−3 mol/L Tiron, 0.04 mol/L tetrabutylammonium bromide, and 0.1 mol/L potassium nitrate. The detection limits for titanium(IV) and iron(III) are 0.5 and 2.0 μg/L, respectively. The method has been applied to the simultaneous determination of titanium(IV) and iron(III) in river water samples and has furnished highly precise results.
Enantiomer separation by capillary SFC and GC on immobilized octakis(2,6‐di‐O‐methyl‐3‐O‐pentyl)‐γ‐cyclodextrin
Authors: Dönnecke Jürgen , König Wilfried A. , Gyllenhaal Olle , Vessman Jörgen , Schulze Christian 
Published: May 2005

AbstractHeptakis(2,6‐di‐O‐methyl‐3‐O‐pentyl) (2‐O‐methyl‐6‐O‐oct‐1‐enyl‐3‐O‐pentyl)‐γ‐cyclodextrin was immobilized to narrow‐bore fused silica capillaries after selective modification. One tert‐butyldimethylsilyl group was introduced into octakis‐(2‐O‐methyl‐3‐O‐pentyl)‐γ‐cyclodextrin in order to get a pure monofunctionalized cyclodextrin derivative. During synthesis the tert‐butyldimethylsilyl group was replaced by an anchoring group to bind the cyclodextrin to a polysiloxane. After thermal immobilization of the modified polysiloxane this new chiral stationary phase was applied in GC and SFC. High efficiency separations were obtained in GC. In SFC very polar compounds could be chromatographed at low temperatures resulting in higher separation factors as compared to GC.
Determination of lysinoalanine by high performance liquid chromatography
Authors: Moret Sabrina , Cherubin Susi , Rodriguez‐Estrada Maria Teresa , Lercker Giovanni 
Published: May 2005

AbstractThis work suggests an HPLC method for qualitative and quantitative determination of Nε(2‐amino‐2‐carboxyethyl)‐L‐lysine (LAL). LAL was released from total hydrolysates of various proteins of animal origin and derivatized with dansyl chloride. The performance of two different columns, Spherisorb 3S TG and μ‐Bondapack C18, was compared; better resolution and quantitative response were obtained with the former. The mobile phase was a mixture of 0.01 M phosphate buffer (pH 7) and acetonitrile. Linear response and quantitative repeatability were tested for both detectors used (UV‐Vis set at 254 nm; fluorimetric set at λex(max) = 360 nm and λem(max) = 525 nm).For LAL standard the minimum detectable amount was 0.05 ng, whereas for LAL in actual samples the amount was 0.5 ng (40 μg/g of analyzed proteins). Good analytical repeatability was obtained, resulting in CV % of 4.7 and 3.8 for UV and fluorimetric detectors, respectively. LAL recovery was determined using both detectors; the values obtained were 94 % (fluorimetric) and 92 % (UV). Greater noise levels were observed with the fluorimetric detector and its higher sensitivity could not, therefore, be fully utilized. The highest amounts of LAL were found in the casein (2816 μg/g) and cooked albumin (615 μg/g) samples.
Evaluation of a low‐resolution near‐IR monochromator for atomic emission detection in capillary gas chromatography
Authors: Pedersen‐Bjergaard Stig , Greibrokk Tyge 
Published: May 2005

AbstractA single 0.2 m focal length near‐IR monochromator providing a 0.8–3.2 nm effective bandpass was evaluated as spectrometer for F‐, Cl‐, Br‐, I‐, S‐, and P‐selective atomic emission detection in capillary gas chromatography. With optimized plasma conditions and careful wavelength selection, interferences from eluting hydrocarbons were almost eliminated for all the elements studied (element‐to‐carbon selectivities between 1000:1 and 10000:1). For Cl and S, other heteroatoms were found not to cause cross‐interferences. F‐, Br‐, I‐, and P‐selective detection, however, was complicated by this second type of non‐specificity. For these atoms, elemental confirmation was carried out by analyzing the samples also for heteroatoms potentially causing interferences.
On‐line capillary supercritical fluid chromatography‐inductively coupled plasma mass spectrometry for the analysis of organometallic compounds
Authors: Blake Earl , Raynor Mark W. , Cornell David 
Published: May 2005

AbstractSupercritical fluid chromatography with inductively coupled plasma‐mass spectrometric detection is a new and useful technique for the analysis of organometallic compounds. An interface has been developed for coupling these techniques. The interface is compact, easy to assembel, and causes minimal disruption to either instrument. A series of organotin, organoarsenic, and organorion compounds has been used to evaluate the interface and ICPMS as a detector for SFC. The effect of analyte concentration and restrictor temperature on peak intensity has been investigated and the effect of the mobile phase on the plasma has also been studied to assess background interference from changes in the plasma.
Separation of lipid classes from plant tissues by high performance liquid chromatography on chemically bonded stationary phases
Authors: Christie William W. , Anne Urwin R. 
Published: May 2005

AbstractThe wide range of lipid classes found in plant tissues, including simple lipids, glycolipids, and phospholipids, have been resolved by gradient high performance liquid chromatography with evaporative light‐scattering detection. The lipids from potato tubers were used to optimize the separations. Adsorption chromatography with silica gel gave disappointing results for the plant glycolipids. Much better separations were obtained with chemically bonded stationary phases, e.g. those with propionitrile or polymeric vinyl alcohol as the functional moiety. With careful calibration, good reproducibility was possible. Only highly acidic lipids such as phosphatidylserine still present some problems.
Determination of ethers and alcohols in reformulated gasolines by gas chromatography/atomic emission detection
Authors: Diehl J. W. , Finkbeiner J. W. , di Sanzo Frank P. 
Published: May 2005

AbstractA GC method for the determination of oxygenated additives in reformulated gasolines (RFG) is described. The method uses on‐column injection and atomic emission selective detection of oxygenates using the 777 nm NIR emission line. Detection limits are approximately 10 ppm oxygen. Results compared well with other techniques, such as GC/FTIR.
HRGC separation of PCB congeners
Authors: Larsen Bo Richter 
Published: May 2005

AbstractHigh resolution gas chromatography has greatly changed the field of polychlorinated biphenyl (PCB) analysis. From a rough estimation of the total PCB concentration on packed column GC, the development of commercially available fused silica capillary columns in the late 1970s and early 1980s has advanced the analysis of PCBs to a point where they can be accurately measured as separated congeners. The state‐of‐the‐art of PCB analysis in the 1990s is routine isomer‐specific analysis with multi‐column techniques using long (<50 m) narrow (> 0.25 mm) columns. A broad spectrum of commercially available stationary phases have been completely characterized with regard to their PCB elution profiles.
Retention properties of a cyanopropylsiloxane‐bonded silica‐based sorbent for solid‐phase extraction
Authors: Seibert Donna S. , Poole Colin F. 
Published: May 2005

AbstractThe characteristic kinetic and retention properties of a silica‐based cyanopropylsiloxane‐bonded sorbent for solid‐phase extraction are described. Abraham′s solvation parameter model is used to characterize the contribution of individual intermolecular interactions to retention under liquid chromatographic and sample processing conditions with aqueous methanol mixtures as the mobile phase. The main features governing retention by the sorbent are the solute's size and hydrogen‐bond basicity; interactions of a dipole type are not significant when aqueous methanol solutions are employed as the mobile phase. Compared to typical silica‐based octadecylsioxane‐bonded sorbents the greater difficulty of forming a cavity in the solvated cyanopropylsiloxane‐bonded sorbent more than offsets the more favorable dipole‐type and solute hydrogenbond base interactions of the cyanopropylsiloxane‐bonded sorbent. It is shown that there are no practical circumstances for which a cyanopropylsiloxane‐bonded sorbent would be more useful than a typical ODS sorbent for the isolation of organic non‐electrolytes from water by solid‐phase extraction.
Application of hyphenated techniques to the chromatographic authentication of flavors in food products and perfumes
Authors: Casabianca Hervé , Graff Jean‐Bernard , Jame Patrick , Perrucchietti Christiane , Chastrette Maurice 
Published: May 2005

AbstractThis work presents two techniques for testing for the adulteration of flavors. One uses multidimensional gas chromatography on cyclodextrin derivatives to separate chiral compounds, the other uses isotope ratio mass spectrometry coupled with gas chromatography to determine stable isotope ratios. Applications to fruits and plants for the food and perfume industry are introduced.
HRGC‐MS and HPLC‐MS identification of new ketosterols in an extract of wheat straw
Authors: Chaves das Neves Higuinaldo J. , Gaspar Elvira M. M. S. 
Published: May 2005

AbstractAn ethereal extract of wheat (Triticum aestivum) straw with a positive biological assay for allelopathic activity, has been analyzed by HRGC. By means of HRGC‐MS the extract composition was assessed as a complex mixture of organic acids and sterolic compounds. The sterolic fraction was subsequently separated and further studied by HRGC‐MS and HPLC‐MS. Among the thirty seven components identified, some described for the first time in wheat straw, two new ketostero's were characterized by means of their MS spectra. The potential of the particle‐beam (PB) interface in HPLC‐MS studies of unknown mixtures is exemplified and compared with that of HRGC‐MS.
An evaluation of solid‐phase microextraction for analysis of volatile organic compounds in drinking water
Authors: Nilsson Torben , Pelusio Fabio , Montanarella Luca , Larsen Bo , Facchetti Sergio , Madsen Jørgen Øgaard 
Published: May 2005

AbstractSolid‐phase microextraction (SPME) has been applied to the quantitative analysis of 60 volatile organic compounds (VOCs) in drinking water. Equilibration curves for the partitioning of the VOCs between the fiber coating and fortified water obtained at 20, 50, and 80 °C are found between the theoretical curves for completely agitated and non‐agitated samples. Two important factors for the amount adsorbed by the SPME fiber coating are the extraction time and the fiber coating/water distribution coefficient, KFW. Both depend on the sample temperature, but in a counteracting manner: Increasing the temperature shortened the equilibration times, especially for the heavier VOCs, but also lead to lower KFW values, and consequently a lower sensitivity of the method. KFW values are determined for 33 of the VOCs at 40, 60, and 80°C and the heats of adsorption,–ΔH, are calculated. The nature of the adsorption is found to be exothermic which explains the decreasing sensitivity of the method with increasing temperature. Detection limits were typically from 20 ng/l to 200 ng/l, except for the very light VOCs with which detection difficulties were encountered. For all of the VOCs the linear range extended from the lowest concentration at which they were actually detected to at least 5 mg/l. The precision, 3% average standard deviation when an internal standard was used, was satisfactory for most quantitative routine analysis. SPME was also applied to head‐space (HS) analysis of drinking water through the coupled equilibrium between water/head‐space/fiber coating. HS‐SPME is demonstrated to have shorter equilibration times than SPME directly from the water and equal sensitivities, except for the very light VOCs. Water samples from a drinking water plant contaminated in the low μg/l range with 1,1,1‐trichloroethane, trichloroethene and tetrachloroethene were analyzed. There seems to be a reasonable agreement between results obtained by SPME and purge & trap. It is concluded that SPME has a great potential for drinking water analysis.
Determination of lactulose and mannitol in urine by HRGC
Authors: Relva Angela M. S. , das Neves Higuinaldo J. Chaves , Ferreira Margarida A. 
Published: May 2005

AbstractAlteration of intestinal permeability towards compounds like sugars is an indication of abnormalities observed in some diseases. Measurement of the dual sugar absorption of lactulose and mannitol is a non‐invasive test of intestinal permeability. The use of this test is however limited by difficulties in the analysis of sugars in urine at low concentrations. In this study we have developed an analytical procedure for quantitative assay of the lactulose–mannitol pair in urine by high resolution gas chromatography. The minimum detectable amounts are 7.5 pg for lactulose and 4.4 pg for mannitol. The calibration curves are linear in the range of 100–6400 mg L−1. Recoveries are within the range 86–102 % for mannitol and 84–105 % for lactulose.
Characterization of polymers by multi‐step thermal desorption/programmed pyrolysis gas chromatography using a high temperature PTV injector
Authors: van Lieshout Mark H. P. M. , Janssen Hans‐Gerd , Cramers Carel A. , Hetem Martin J. J. , Schalk Huub J. P. 
Published: May 2005

AbstractThermal treatment hyphenated with gas chromatography is a versatile and powerful tool in the study of polymer characterization. An inexpensive system where thermal treatment at different temperatures occurs inside a Programmable Temperature Vaporization injector (PTV) is described. The samples investigated, commercial plastics, are complex mixtures that contain several polymers and additives. These plastics as well as their pure constituents are subjected to multi‐step thermal treatment. The individual chromatograms of the various constituents of the polymeric sample are correlated with those of the final material in order to identify additives (thermal desorption) and degradation products (pyrolysis). Results obtained with the new method indicate the interesting potentials of the technique for the characterization of polymer compositions. Reproducibility of absolute and relative peak areas has been considered and found to be acceptable. The absence of a heated transfer line and switching valves, which are always present in conventional set‐ups, eliminates the risk of losses of high molecular weight components. Further advantages of the technique proposed are simplicity, versatility, and its inexpensive nature.
Gas‐chromatographic headspace analysis of phenol and cresols in soils by direct acetylation
Authors: Llompart‐Vizoso Maria P. , Lorenzo‐Ferreira Rosa A. , Cela‐Torrijos Rafael 
Published: May 2005

AbstractA quick, simple and selective procedure has been developed for the determination of phenol, o‐cresol, m‐cresol, and p‐cresol in soil samples. The method is based on the gas chromatographic headspace analysis of phenols as acetate derivatives. These acetates were prepared directly in the wetted soil samples by acetic anhydride in the presence of KHCO3˙ With this procedure sample handling is reduced to a minimum as desorption and derivatization of the analytes are developed from the wetted samples inside the vial of the head space sampler.The acetate esters were analyzed using a 60 m × 0.56 mm DIIDP capillary column (di‐isodecyl‐phthalate), using 2‐chlorophenol as an internal standard. The detection limit was between 0.03–0.08 μg g−1 for the different species considered. Soil samples having carbon contents lower than 5 % can be analyzed by the proposed procedure.
A four factor simplex optimization of a serially coupled open tublar columns gas chromatographic system
Authors: Bakeas Evangelos B. , Siskos Panayotis A. 
Published: May 2005

AbstractOptimization of a gas chromatographic system with two capillary columns coupled in series in a single oven for the linear temperature programmed separation of a mixture of C1C10 hydrocarbons has been carried out using the simplex optimization method. The following four selectivity parameters were optimized: the initial temperature of the oven; the initial hold time; the temperature programmed rate; and the pressure at the mid‐point of the system. The optimization procedure was monitored by the Cp criterion.
Use of vancomycin as chiral selector in capillary electrophoresis. Optimization and quantitation of loxiglumide enantiomers in pharmaceuticals
Authors: Fanali Salvatore , Desiderio Claudia 
Published: May 2005

AbstractVancomycin has been used as chiral selector for the enantiomers separation of D, L‐loxiglumide, a new drug proposed for the treatment of gastrointestinal pathology. The chiral selector, dissolved at very low concentration in the running buffer, filled only part of the capillary (polyacrylamide coated) and allowed chiral resolution in less than 12 min using a 50 mM phosphate buffer at pH 6. The partial separation technique allowed to obtain a detection limit of 0.5 μg/ml for each enantiomer avoiding the drop in sensitivity due to the strong UV absorption of vancomycin when present in the detector path. The effects of vancomycin concentration and buffer pH on enantiomers resolution have been studied in order to find the optimum experimental conditions for the chiral purity control of drug. The optimized method, using the internal standard, showed good reproducibility for both migration times and normalized peak area ratio and for linearity. Under the studied operating conditions it was possible to detect 0.2 % (w/w) of L‐loxiglumide as a chiral impurity. Analysis of pharmaceutical preparations of D‐loxiglumide did not reveal the presence of the impurity (L‐isomer).
Retention index system, adsorption characteristics, and structure correlations of polycyclic aromatic hydrocarbons in fuels
Authors: Elizalde‐González María P. , Hutfließ Markus , Hedden Kurt 
Published: May 2005

AbstractPart of this work focuses on temperature programmed retention index assessment of 70 polynuclear aromatic hydrocarbons (PAHs) using a methylsilicone capillary column. The use of the retention index presented here offers a good possibility of identifying and determining PAHs in the mass range discussed and to apply such conditions to the analysis of fuel deposits. Retention indices and vaporization enthalpy data of PAHs are linearly related to the molecular total energy. This paper describes also a gas‐chromatographic study of the adsorption of some PAHs on Carbopack.
Gas chromatographic determination of some glycol ethers and glycol ether acetates by FID, O‐FID, and MS detection. Preliminary applications in simultaneous monitoring of these chemicals in biological matrices
Authors: Giachetti Claudio , Zanolo Giovanni , Verga Giuseppe R. , Perovanni Fabio , Assandri Alessandro 
Published: May 2005

AbstractTwelve compounds, commonly used as industrial solvents and belonging to the chemical class of glycol ethers and glycol ether acetates, were investigated. Several analytical conditions, applied to single or connected capillary columns of different length and polarity coating and connected to FID, O‐FID and MS detection systems, were assayed. Tests on heptafluorobutyryl derivatives were also attempted to improve the analytical sensitivity. The aims were to establish gas chromatographic methods suitable for analysis of reference standard compounds and to verify their applicability to biological matrix analysis for pharmacokinetic and toxicological studies, since these chemicals have been shown to be hazardous in laboratory animals and are presumed to be dangerous in man.