bluuebunny/crossref_metadata_2025_split huggingface dataset:
Pulsed discharge photoionization detector: Application to analysis of chloro alkanes/alkenes
Authors: Wentworth Wayne E. , Li Yulan , Stearns Stanley D. 
Published: May 2005

AbstractA windowless pulsed discharge photoionization detector (PDPID) is described which uses the emission spectra from the discharge in helium and Ar/Kr doped helium. The emission from helium is a continuum ranging from 13.5–17.7 eV which ionizes all compounds except neon. The emission from 5.4% Ar/He ranges from 9.3–11.8 eV and ionizes most organic compounds and many inorganic compounds. The emission from 1.36% Kr/He consists principally of the resonance lines at 10.6 and 10.1 eV. These PDPIDs are used to analyze a 12 component mixture containing principally chloro alkane/alkene. The relative responses of the PDPID combined with the relative retention time can be used to qualitatively identify the chloro compounds.
Thermal treatment for immobilization of chiral polysiloxanes in capillary gas chromatography
Authors: Abe Iwao , Terada Kenji , Nakahara Taketoshi 
Published: May 2005

AbstractThe chiral selector L‐t‐leucine‐t‐butylamide has been anchored to a polysiloxane by nucleophilic displacement of 2,2,2‐trifluoroethyl ester‐functionalized block polysiloxanes with L‐t‐leucine‐t‐butylamide. Attempts were made to immobilize the chiral polysiloxanes inside the capillaries by thermal treatment at 300°C for 30–90 min. The polysiloxanes were found to be more resistant than Chirasil‐Val to the racemization caused by such high temperature treatment. Capillary columns coated with this type of immobilized polysiloxane have shown very high enantioselectivity and thermal stability.
Determination of inorganic anions in Kraft pulping liquors by capillary electrophoresis
Authors: Masselter Sonja M. , Zemann Andreas J. , Bonn Günther K. 
Published: May 2005

AbstractVarious sulfur containing anions (sulfate, sulfite, and thiosulfate) in Kraft pulping process liquors are determined by capillary electrophoresis. In addition, other inorganic anions (hydroxide, chloride, oxalate, carbonate) are analyzed with the developed method. Through optimization of the separation conditions it is possible to simultaneously determine these anionic species in pulping liquors with direct and indirect UV detection at 185, 214, and 254 nm. To ensure short separation times a migration of the anionic analytes in the same direction as the electroosmotic flow (co‐electroosmotic CE) is established by reversal of the electroosmotic flow with 1,5‐dimethyl‐1,5‐diazaundecamethylene polymethobromide (hexadimethrine bromide; HDB; polybrene™) which is added to the electrolyte as EOF modifier. The impact of acetonitrile as organic modifier to improve the selectivity of the anionic analytes is also investigated. The developed method is then applied to analyze and quantify various anions in pulping liquors (white and black liquors). By simultaneously determining the hydroxide concentration it is possible to calculate effective alkalinity and sulfidity with the measured concentrations without the need of volumetric methods.
Sampling volatile organic compounds using a modified solid phase microextraction device
Authors: Zhang Zhouyao , Pawliszyn Janusz 
Published: May 2005

AbstractHeadspace solid phase microextraction (headspace SPME) has been demonstrated to be an excellent solvent‐free sampling method. One of the major factors contributing to the success of headspace SPME is the concentrating effect of the fiber coating toward organic compounds. The affinity of the fiber coating toward very volatile analytes, such as chloromethane, may, however, not be large enough for detection at the parts per trillion concentration level. Static headspace analysis, on the other hand, is very effective for these very volatile compounds. As analyte volatility decreases, the sensitivity of static headspace analysis drops. The complementary nature of these two sampling methods can be exploited by combining the SPME device with a gastight syringe. The sensitivity of the new sampling device is better than that of SPME for very volatile compounds or that of static headspace analysis for less volatile compounds. This new method can sample a wide range of compounds from chloromethane (b.p. −24°C) to bromoform (b.p. 149°C) with estimated limits of detection at the low parts per trillion level.
Determination of chelating agents in Hanford tank waste simulant by capillary zone electrophoresis
Authors: Ballou Nathan E. , Ducatte Gerald R. , Quang Changyue , Remcho Vincent T. 
Published: May 2005

AbstractA capillary electrophoretic method has been developed which achieves rapid quantitative separation and determination of ethylenediaminetetraacetic acid, N‐(2‐hydroxyethyl)ethylenediaminetriacetic acid, diethylenetriaminepentaacetic acid, ethylenediaminediacetic acid, and nitrilotriacetic acid in Hanford tank waste simulant (TWS). Direct UV detection of Cu2+/chelator complexes is used to achieve enhanced sensitivity. The qualitative and quantitative reliability of the method and the quality of separations, as given by efficiency and resolution, is presented. In addition, the limits of detection and linearity of detector response with concentration are given for each chelator. The selection of Cu as the UV‐absorbing species over other transition metals present in the waste is discussed.
Analysis of Carbaryl and carbofuran in tobacco samples by HRGC, HPLC, and CZE
Authors: Lanças Fernando M. , Rissato Sandra R. , Galhiane Mário S. 
Published: May 2005

AbstractDetermination of carbamate residues in tobacco samples was carried out by three different methods, two having been described in the literature and one developed for the purpose of this work. The extracts were analyzed by HRGC‐FID (using derivatization), by HPLC‐RP with photodiode array detection and by Capillary Zone Electrophoresis (CZE) with UV detection. The extraction method developed used in conjunction with capillary zone electrophoresis showed to be the most suitable for carbamate residue analysis in real tobacco samples. The developed method presented better recovery results in relation to the others. CZE allowed the determination of carbamate residue in real tobacco sample while HPLC and HRGC could not do this, due to co‐elution problems.
High speed analysis of H2S and COS impurities in coal gas by capillary gas chromatography
Authors: Laurens J. B. , Rohwer E. R. 
Published: May 2005

AbstractThere is a need for rapid, on‐line, gas chromatographic analysis of trace levels of hydrogen sulfide and carbon oxysulfide in the oil‐from‐coal industry. In order to improve an existing method based on a polymer bed concentrator, a porous layer open tubular column, and a flame photometric detector, time‐optimization of the various steps involved was attempted. Use of a redesigned concentrator, changed column operating conditions, and a photoionization detector reduced analysis times from 6.5 to 3 min and cycle times from 8 to 3 min. This could be achieved without compromising the 10 ppb detection limit required.
Systematic optimization of the analysis of wine bouquet components by solid‐phase microextraction
Authors: García Demetrio De la Calle , Magnaghi Silvana , Reichenbächer Manfred , Danzer Klaus 
Published: May 2005

AbstractThe extraction, identification, and quantification of wine aroma compounds are preliminary steps required for further investigation of wine quality, i.e. determination of the varieties of grapes used, the production process, and the origin and age of the wine. This paper deals with the optimization of solid‐phase microextraction for the determination of compounds which produce wine bouquet. Optimum operating conditions have been determined to obtain high reproducibility at low cost and with low time‐consumption. Several factors influencing the equilibrium of the aroma compounds between the sample and the fiber must be taken into account, including length of contact time between the two phases involved, speed of agitation of the sample, the matrix in which the process takes place, and, furthermore, the place, duration, and temperature of desorption in the injector of the chromatograph.
HRGC separation performance evaluation by a simplified fourier analysis approach
Authors: Pietrogrande Maria Chiara , Dondi Francesco , Felinger Attila 
Published: May 2005

AbstractA simple procedure is presented for determining separation performance of HRGC analysis of multicomponent mixtures. The procedure is based on the computation of Autocovariance Function (EACVF) from the digitized experimental chromatogram. Graphic inspection of the EACVF plot permits easy computation of the width value of the single component peak, σ; from the EACVF value at t=O the number of component in the mixture, m, can be simply derived. From these two basic quantities all the other chromatographic performance attributes can be calculated. The consistency of the procedure is tested for different chromatograms and compared with the more complex EACVF fitting method. Several features of the multicomponent chromatogram, overloading effects included, are directly detected.
Determination of triclosan in human dental plaque by gas chromatography with atomic emission detection
Authors: Rasmussen Henrik T. , McDonough Robert , Gargiullo Robert J. , McPherson Bruce P. 
Published: May 2005

AbstractA validated gas chromatographic method for the determination of triclosan in human dental plaque is described. Based on plaque sample weights of 10 mg, the limit of detection (2 × S/N) is 0.5 μg/g. The method is linear (r = 0.9986) from the limit of detection to 50 μg/g. Recoveries from placebos spiked with 2.0, 25, and 50 μg/g of triclosan were 105.6%±7.5%, 107.2%±3.1%, and 99.1%±1.1%, respectively (n = 3 at each level). Twenty replicate preparations and analyses of a homogenized sample, conducted by two operators over the course of 4 days, showed agreement to within 9% RSD. Analyses of dental plaque collected from patients after brushing with dental cream containing triclosan, shows triclosan to be retained in dental plaque at concentrations above the minimum inhibitory concentration (1 μg/g) after 12 h.
The use of predicted boiling points for the identification of halobenzenes and substituted phenols in capillary gas chromatography
Authors: Gerbino Tomaso C. , Castello Gianrico 
Published: May 2005

AbstractQuantitative correlations between physicochemical parameters and structure of various solutes and their gas chromatographic behavior were investigated in order to predict the retention values. The identification of unknown samples in gas chromatographic routine analysis of environmental samples is enhanced by the use of these correlations in conjuction with other chromatographic methods and with mass spectrometry. The boiling points of many compounds are easily found in literature and therefore their correlation with retention values obtained in isothermal or programmed temperature analysis permit restriction of the choice of names of unknown compound to within a narrow range. The correlation between the boiling points and the retention times of chloro‐ and bromo‐benzenes and of some chloro‐ and nitro‐ substituted phenols was investigated on non‐polar capillary columns and permitted the tentative identification of many compounds belonging to these homologous series.
Quantification and determination of enantiomeric ratios of chiral PCB 95, PCB 132, and PCB 149 in shark liver samples (C. coelolepis) from the Atlantic Ocean
Authors: Blanch Gracia P. , Glausch Alexandra , Schurig Volker , Serrano Roberto , Gonzalez María José 
Published: May 2005

AbstractChiral 2,2′,3,5′,6‐pentachlorobiphenyl (PCB 95), 2,2′,3,3′,4,6′‐hexachlorobiphnyl (PCB 132) and 2,2′,3,4′,5′,6‐hexachlorobiphenyl (PCB 149) were quantified in Atlantic Ocean shark liver samples (C. coelolepis) by gas chromatography‐mass spectrometry (GC‐MS) and their enantiomeric ratios were studied by multidimensional gas chromatography (MDGC) with an achiral‐chiral column combination and detected by ECD and MS/SIM. The concentration range of the chiral PCBs was from 2 to 6 ng/g (fresh weight), which represents 2–6 % of the total PCB mean concentration. The investigations revealed a small enantiomeric bias of PCB 132 in most of the samples studied (ER = 0.75–0.89, ee = 6–14%), while PCB 95 and PCB 149 were present in racemic or almost racemic form.
Recovery of fortified (2 ppb) EPA method 525.1 analytes from Chesapeake Bay water via solid phase deposition followed by supercritical fluid elution
Authors: Messer D. C. , Taylor Larry T. 
Published: May 2005

AbstractApplication of solid phase deposition/supercitical fluid (SPD/SF) elution to real, brackish water samples, obtained from the Chesapeake Bay, has been investigated. The fortified (2ppb) brackish water samples contained suspended sediment, dissolved organic matter and salt. The sediment made post‐deposition drying of the SPE disk difficult and the residual water interfered with analyte recovery. Attempts to dry the disk included increasing the vacuum drying time, use of a higher percent of modifier, and desiccation. The best results were obtained by first drying the disk for 10 min under a stream of nitrogen, followed by overnight desiccation, and finally, SF elution. The SF method required a 3 step, 42 min extraction which reduced organic solvent use by 60% compared to traditional elution. All but five analytes met EPA criteria when fresh desiccant was used to dry the disk; four of the unacceptable recoveries were presumably due to plasticizer contamination.
Suitability of automated capillary and micro liquid chromatography for routine determination of drugs in human plasma samples from clinical pharmacokinetic investigations
Authors: Malavasi Bruno , Ascalone Vittorio 
Published: May 2005

AbstractOne of the most widely acclaimed features of capillary and microcolumn LC, in comparison with conventional HPLC, is the enormous increase in mass sensitivity. Nevertheless, application of capillary and micro LC in quantitative trace bioanalysis, characterized by weak analyte concentrations in complex matrices, can only be of any practical utility if large sample volumes can be injected onto the columns without affecting chromatographic resolution and efficiency.Two applications of large volume injection in a non‐eluting solvent (on‐column focusing) for the quantitative analysis of drugs in biological fluids on both capillary and micro chromatographic systems are presented: the first example deals with a new selective H1‐antihistaminic drug, mizolastine, the second one with a well known calcium antagonist, diltiazem, and its main metabolites. For both compounds, results obtained on micro and capillary LC in comparison with conventional HPLC are reported. The results demonstrate that when conventional HPLC methods are transformed into either micro or capillary LC techniques, they gain in sensitivity. By means of an on‐column focusing technique, it is possible to increase the sensitivity 3–5 fold in comparison to conventional HPLC methods, but not 50–60 fold as obtained on synthetic drug solutions. Column robustness, handiness, reproducibility, and suitability of micro systems for routine bioanalysis are discussed for both capillary and micro LC columns, as well as limits of the technique in trace organic analysis problems.
Enantiomer separation of amino acids as their N‐alkyloxycarbonyl alkylamide derivatives by chiral phase capillary GC
Authors: Abe Iwao , Nakahara T. 
Published: May 2005

AbstractThe enantiomers of amino acids were first converted into N‐alkyloxycarbonyl 2,2,2‐trifluoroethyl esters, and then into N‐alkyloxycarbonyl alkylamides by nucleophilic substitution of the ester group with amines. The first reaction proceeds instantaneously, while the second substitution occurs smoothly with n‐propylamine and isobutylamine. The final derivatives were produced for separation on a capillary column coated with Chirasil‐Val by GC. Pro, which is difficult to separate completely as its N‐perfluoroacyl alkyl ester derivative, showed complete separation of the enantiomeric pair. All amino acids examined in this study showed an increased separation factor.
Solid phase extraction of halogenated pesticides from ground and surface waters and their determination by capillary gas chromatography
Authors: Báez María E. , Lastra Olga , Rodríguez Manuel 
Published: May 2005

AbstractA critical study of a solid phase extraction method using C18 SPE columns for the determination of 23 halogenated pesticides is presented. Type of sorbent, sorbent mass, flow rate in the extraction process, sample concentration of the different compounds, sample volume, pH, ionic strength and type of water were evaluated. Recoveries of pesticides under study yield a linear relationship, except for conazole fungicides and captan. Losses can be expected for heptachlor, aldrin, and captan. Sample volume and flow rate of extraction affect recoveries. Matrix effects from surface and groundwaters were observed. Recoveries for vinelozolin and dieldrin from groundwater were lower than those obtained from nanopure water. In river water losses of these compounds are higher. Captan and penconazole were not present and high losses were obtained for trifluralin, α‐BHC, γ‐BHC, tri‐allate and chlorpyriphos. Impurities arising from the sorbent materials of cartridges have been detected.
Capillary zone electrophoresis with UV‐scanning detection for the analysis of metal species and their organic binding partners in biological systems
Authors: Theobald Anne , Dunemann Lothar 
Published: May 2005

AbstractA capillary zone electrophoretic method with UV‐scanning detection for the separation and identification of both free ligands and metal species is presented. The electrophoretic behavior of naturally occurring binding partners such as organic acids and amino acids was studied and compared with their metal‐complexes. Copper(II) complexes of citrate and amino acids showed decreased electrophoretic mobilities and altered UV spectra. The optimized method was validated on ultrafiltered cow's milk and human milk samples. In cow's milk six low molecular weight substances, including citrate, orotate, and hippurate, could be separated. Metal supplementation with Cu(II), Ni(II), or Zn(II) decreased not only the citrate peak but also the orotate signal and in the case of copper(II) supplementation a new signal for the copper(II)‐citrate complex appeared. In human milk samples various amino acids such as glutamate, phenylalanine, tyrosine, and tryptophan could be identified besides citrate. The electrophoretic mobilites and peak areas of the amino acids were also influenced by the metal supplementation.
High performance fourier transform ion cyclotron resonance mass spectrometric detection for capillary electrophoresis
Authors: Hofstadler Steven A. , Severs Joanne C. , Smith Richard D. , Swanek Frank D. , Ewing Andrew G. 
Published: May 2005

AbstractWe describe the current state of the on‐line combination of capillary electrophoresis (CE) electrospray ionization (ESI) Fourier transform ion cyclotron resonance (FTICR) mass spectrometry (MS), and discuss aspects of the FTICR technique relevant to its use as a detection scheme for on‐line separations. Aspects including sensitivity, mass resolution, duty cycle, and tandem mass spectrometric capabilities are discussed in the context of online separations with examples from the authors' laboratory.
Multidimensional capillary gas chromatography of polychlorinated biphenyl marker compounds
Authors: Kinghorn Russell M. , Marriott Philip J. , Cumbers Mark 
Published: May 2005

AbstractMultidimensional chromatography was used to resolve the specific chlorobiphenyl (CB) congeners 28, 52, 101, 118, 138, 153, and 180 in technical aroclor standards. Single column analysis of polychlorinated biphenyls (PCBs) results in co‐elution of key congeners with other components in the mixture; therefore using two columns of different selectivity was necessary to enhance the resolution achievable on just one column. The HT8 column (8% phenylpolycarborane‐siloxane phase) has been reported to have specific selectivity characteristics for improved PCB separation. When coupled with a BPX5 column (5% phenylpolysiloxane‐silphenylene phase), it has been shown here to provide unambiguous identification of 7 marker compounds which are used to monitor PCB occurrence and distribution. All seven marker CBs are present in aroclor 1254, and by adjusting the size of the heartcut window, it was possible to obtain resolution of the marker congeners from other congeners. Single column analysis is unable to achieve this result. This offers an alternative to GC‐MS analysis.
Atmospheric monitoring of volatile organic compounds using programmed temperature vaporization injection
Authors: Lewis Alastair C. , Bartle Keith D. , McQuaid James B. , Pilling Michael J. , Seakins Paul W. , Ridgeon Peter 
Published: May 2005

AbstractA method has been developed for the automated determination of C5C10 and C2C6 volatile organic compounds in urban and rural air, using programmed temperature vaporization injection from a sorbent tube trap. A single activated charcoal sorbent tube was repeatedly used to collect samples of air with trapped VOCs being subsequently desorbed onto either a wide bore dimethyl polysiloxane (C5C10) or porous layer open tubular (C2C6) gas chromatography column without use of intermediate cryogenic refocussing. The high flow rates of helium used during the analysis resulted in the sample tube being cleaned and ready to reuse following the analytical separation. Examples of analysis of aromatic VOCs in urban air, and biogenic emissions in rural air, collected in a Sitka Spruce forest are presented. Using this method it is possible to quasi‐continuously monitor concentrations of VOCs in locations where high sensitivity in situ analysis is required, but where cryogenic coolants may not be readily available or desirable.
Determination of polar analytes in aqueous matrices by purge and trap
Authors: Kaufmann Anton 
Published: May 2005

Abstract(not readable) fully autimated purge and trap system has been developed for (not readable) detemination of volatile wine components. The proposed system consists of sampler, a purge and trap instrument, and a GC, (not readable) steps, from the uptake of the infiltrated wine from the sampler (not readable) to the printout of the intergrated chromatograms, proceed(not readable), Typical problems occurring when analyzing polar analytes by the classical purse and trap approach have been specifically addressed. The system has been desiggned to handle such difficult (not readable) analytes. Efforts have been made to improve the reproducibility and the carry‐over of these analytes. The measures adopted include: thorough rinsing and subsequent conditioning of the P + T parger; elimination of matrix effects by dilution and high salt (not readable); tight specification of purge relevant parameters; split‐inter‐(not readable) to improve GC retention time reproducibility.