bluuebunny/crossref_metadata_2025 huggingface dataset:
Preparation of amino‐zirconia bonded phases and their evaluation in hydrophilic interaction chromatography of carbohydrates with pulsed amperometric detection
Authors: Yu Jim , Rassi Ziad El
Published: May 2005

A series of non‐porous, microspherical zirconia‐based stationary phases with surface bound amine functionality have been introduced and evaluated in hydrophilic interaction chromatography (HILIC) of underivatized, neutral carbohydrates and anion exchange chromatography of nucleotides using pulsed amperometric detection and ultraviolet detection, respectively. Three aminopropyl alkoxysilane compounds were used in the surface modification of the non‐porous zirconia support, namely 3‐aminopropyltrimethoxysilane (monoamine), N‐(2‐aminoethyl)‐3‐aminopropyltrimethoxysilane (diamine), and trimethoxysilylpropyldiethylenetriamine (triamine). Due to the relatively low specific surface area of the non‐porous zirconia support used in this study (ca. 7.3 m2/g), zirconia with surface coating of the triamine type yielded the best results as far as the separations of chitooligosaccharides and maltooligosaccharides are concerned. Since a non‐porous zirconia could be readily modified with amine functionality via ZrOSi bonds, it is expected that all the three aminopropyl alkoxysilane compounds would yield satisfactory results with porous zirconia microparticles because of their much higher specific surface areas. Although the non‐porous zirconia exhibited some limitations, the present study has demonstrated that microspherical zirconia particles are suitable supports for the production of polar sorbents for HILIC of carbohydrates. Another surface modification, which involved the activation of the zirconia surface with aldehyde groups followed by reductive amination with tetraethylenepentamine, was also evaluated. Although this chemistry would in principle yield sorbents with higher concentration in amine groups, the conversion of the majority of the primary amine groups of the tetraethyle‐nepetamine molecules to secondary amine functions in the course of the reductive amination reaction have provided a stationary phase that did not afford satisfactory resolution for carbohydrates. However, this same stationary phase behaved as a weak anion exchanger and allowed the high resolution separation of nucleoside‐5′‐mono‐, ‐di‐, and triphosphates. Overall, the results obtained with zirconia‐based hydrophilic sorbents paralleled those obtained on amino‐silica bonded phases.
Optimizing the gas chromatographic separation and detection of polychlorinated biphenyls by use of electronic pressure programming and experimental design
Authors: Chen Chiu‐Yun , Ling Yong‐Chien
Published: May 2005

The applicability of electronic pressure control and Taguchi L27 experimental design to the optimization of the gas chromatographic separation and detection of polychlorinated biphenyls has been evaluated. The influence of several experimental variables, column temperature program, carrier gas pressure program, on‐column injector temperature program, and make‐up gas pressure program, was studied using analysis of variance. Simultaneous optimization of sample introduction, column efficiency, and detector performance could be achieved without compromising system performance. The relationships between system performance and experimental variables were established using regression analysis. Agreement between the simulated and experimental results obtained using suggested optimum conditions demonstrated the applicability of the technique developed in this study. The improvement achieved in the chromatographic separation of PCBs is presented.
Direct coupling of capillary supercritical fluid chromatography with supercritical fluid extraction using modified carbon dioxide
Authors: Daimon Hiroyuki , Hirata Yukio
Published: May 2005

Capillary supercritical fluid chromatography has been directly coupled with supercritical fluid extraction using modified carbon dioxide. The mixed fluids were prepared with a single pump on‐line mixing system. The most important step in the SFE‐SFC interface was the elimination of the modifier solvent. This was achieved by use of a coupled trap, 0.1 mm i.d. and 0.53 mm i.d. capillary tubing connected in series, with the collected solutes refocused on the second (0.53 mm i.d.) trap before transfer into the separation column. This enabled complete elimination of various modifier solvents and high efficiency collection of the solutes. The effect of the modifier on trapping efficiency was investigated using methanol, ethanol, dichloromethane, hexane, and toluene at a variety of concentrations. n‐Eicosane was, for example, trapped quantitatively by modified carbon dioxide containing up to 13 % (w/w) methanol. The use of the technique has been demonstrated by selective extraction of n‐paraffins, fatty acid methyl esters, and alcohols from a silica matrix; the effect of different modifiers on the extraction of a mixture of pesticides from soil has also been investigated.
Large volume sample introduction using temperature programmable injectors: Implications of liner diameter
Authors: Mol Hans G. J. , Janssen Hans‐Gerd , Cramers Carel A. , Brinkman Udo A. Th.
Published: May 2005

Temperature programmable injectors with liner diameters ranging from 1 to 3.5 mm are evaluated and compared for solvent split injection of large volumes in capillary gas chromatography. The liner dimensions determine whether a large sample volume can be introduced rapidly or has to be introduced in a speed controlled manner. The effect of the injection technique used on the recovery of n‐alkanes is evaluated. Furthermore the influence of the liner diameter on the occurrence of thermal degradation during splitless transfer to the analytical column is studied. Guidelines are given for the selection of the PTV liner internal diameter best suited for specific applications.
Column liquid chromatography coupled on‐line with mass spectrometry using post‐column phosphate suppression
Authors: Debets Alexander J. J. , Mekes Tanja J. L. , Ritburg Andrew , Jacobs Peter L.
Published: May 2005

The coupling of column liquid chromatography on‐line with mass spectrometry using post‐column phosphate suppression is described. A membrane suppressor is used to remove the non‐volatile phosphate ions from the mobile phase after the chromatographic separation prior to introduction into the mass spectrometer. Using post‐column phosphate suppression by a membrane device phosphate concentrations up to 10 mM phosphate, at a mobile phase flow rate of 0.1 ml/min, could be removed for more than 99% without any decay of the sensitivity of the MS detection.

Using a new antidepressant tetracyclic basic compound, ORG 4428, and some structure related compounds as model compounds electron impact as well as chemical ionisation spectra of all compounds could be obtained. The set‐up could be used for several weeks running, using a phosphate containing mobile phase, without any loss of performance.
Catalytic transformation of copaiba (Copaifera officinalis) oil over zeolite ZSM‐5
Authors: Stashenko Elena , Wiame Hughes , Dassy Stephane , Martinez Jairo René , Shibamoto Takayuki
Published: May 2005

The oil extracted from the trunk of the copaiba tree (Copaifera officinalis) is composed of sesquiterpenes, C15H24, and a small amount (>7 %) of sesquiterpenols, C15H26O; these were identified from their Kováts indices and mass spectra. The use of zeolites in the catalytic transformation of this renewable source of hydrocarbons is of interest in the search for new chemicals and ecologically clean fuels. Oil samples from copaiba trees growing in Colombia's Oriental Plains were circulated over zeolite ZSM‐5 in a continuous flow fixed‐bed micro reactor at 225, 265, and 325°C, for 1 h and subsequently analyzed by HRGC and GC‐MS. Whereas only thirty four sesquiterpenes were identified in the original oil, over two hundred compounds were found in the product of the treatment of copaiba oil with zeolite ZSM‐5. This complex mixture of sesquiterpenes, light aromatic compounds, and indene and naphthalene derivatives resulted from reactions such as isomerization, hydrogenation, cracking, and dehydrogenation with and without cracking. The amount of cracking products and aromatic compounds increased with reactor temperature but decreased with catalyst aging.
Trace analysis of airborne haloacetates
Authors: Frank Hartmut , Renschen Dirk , Klein Armin , Scholl Harald
Published: May 2005

Haloacetates in various environmental compartments can be determined by gas chromatography‐negative‐ion chemical‐ionization mass spectrometry after derivatization with 1‐pentafluorophenyl diazoethane. Detection limits in absolute amounts per injection are between 0.01 fg (chlorodifluoroacetate) and 80 fg (monofluoroacetate). Sampling of haloacetates in urban air was performed by means of cylindrical denuders coated with alkalized glycerol. The haloacetates detected are trifluoro‐, monochloro‐, dichloro‐, trichloro‐, monobromo‐, and dibromoacetate. The concentrations in ambient air fluctuate strongly, e.g. between 20 and 3000 pg/m3 for TFA. Haloacetates are also found in river waters and tree foliage. A major problem is interference from contamination with trifluoro‐ and trichloroacetate.
Analysis of triacylglycerol positional isomers by silver ion high performance liquid chromatography
Authors: Adlof Richard O.
Published: May 2005

Silver ion chromatography, utilizing two commercially available HPLC columns connected in series, was used to separate a variety of triacylglycerol positional isomers. The isomers had a fatty acid composition of ABA and AAB, where A and B were fatty acids containing zero to three double bonds. Isocratic solvent systems of 0.5% to 1.0% acetonitrile in hexane were used to separate the triacylglycerol isomers. This methodology can be used to rapidly determine the isomeric purity of synthesized or isolated triacylglycerols and to isolate specific positional isomers.
Comparison of polydimethyl siloxane stationary phases with 5% and 50% phenyl substitution for the separation of organophosphorus and organonitrogen pesticides under optimized gas chromatographic conditions
Authors: Sippola Erkki , David Frank , Sandra Pat
Published: May 2005

The CGC analysis of 25 organophosphorus and organonitrogen pesticides was optimized on two different stationary phases, namely a 5% diphenyl dimethyl silicone (SE‐54 type) and a 50% diphenyl dimethyl silicone (OV‐17 type) by selecting the best temperature program conditions, using computer simulation.
Analysis of amine compounds by capillary gas chromatography using ammonia–helium carrier gas
Authors: Ghaoui Labib , Pell Karen , Chritz Karen , Loomis Robert N.
Published: May 2005

The use of 10%, 1%, and 0.1% ammonia in helium as carrier gas was investigated as a means of improving poor chromatographic peak shape often associated with low level determinations of amine compounds using thin film capillary columns. The 1% ammonia in helium was found suitable for improving the peak shape of sterically unhindered amine compounds, such as urethane and certain aliphatic primary amines, during gas chromatographic analysis on thin film columns. There was a negligible effect on the peak tailing arising on thick film columns. The 0.1% ammonia in helium was suitable, but not as efficient as the 1% ammonia in helium, in eliminating the peak tailing associated with low level analysis of amine compounds. The signal‐to‐noise (S/N) ratio improved from < 1 using helium carrier gas to 20–25 (for certain test amine compounds) using 1% ammonia in carrier gas. The 10% ammonia in helium carrier gas had an effect on the chromatographic performance similar to that of the 1% ammonia in helium, but the baseline level was very high and this mixture was not used in further studies.
Cyclodextrin carbamates as novel chiral stationary phases for capillary gas chromatography
Authors: Takeichi Tsutomu , Toriyama Hisashi , Shimura Shigeru , Takayama Yuzi , Morikawa Masami
Published: May 2005

The following carbamate derivatives of cyclodextrins (CDs) were prepared as novel chiral stationary phases for capillary gas chromatography: hexakis(2,6‐di‐O‐pentyl)‐α‐cyclodextrin hexa(3‐n‐propyl, 3‐isopropyl, and 3‐phenylcarbamate), heptakis‐(2,6‐di‐O‐pentyl)‐β‐cyclodextrin hepta(3‐n‐propyl, 3‐isopropyl, and 3‐phenylcarbamate), and octakis(2,6‐di‐O‐pentyl)‐γ‐cyclodextrin octa(3‐n‐propyl, 3‐isopropyl, and 3‐isopropyl, and 3‐phenylcarbamate). Metal capillary columns coated with these stationary phases resolved many kinds of racemic mixture. In general, they were especially effective towards polar compounds such as free alcohols, amines, and epoxides. The types of sample which were effectively resolved depended on the cavity size of the CD: α‐CD derivatives were specifically effective toward compounds having linear alkyl chains, and β‐CD derivatives toward compounds with phenyl groups. The results indicate that chiral separation with the cyclodextrin carbamates depends on the formation of inclusion complexes and also on the hydrogen‐bonding interactions between the samples and the CD carbamates.
Quantitative analysis of the mono‐ and sesquiterpenoids of douglas‐fir sapwood by solvent extraction and gas chromatography with mass selective detection
Authors: Kimball Bruce A. , Craver Rori K. , Johnston John J. , Nolte Dale L.
Published: May 2005

In order to investigate the relationship between terpenoid content and black bear foraging preference, an analytical method was required to quantify mono‐ and sesquiterpenoids present in Douglas‐fir sapwood. Sapwood samples were scraped from trees, immediately frozen in liquid nitrogen, and then homogenized. A simple extraction requiring no clean‐up step was performed with ethyl acetate. Extracts were analyzed by gas chromatography with mass selective detection versus external standards. The recoveries of 22 terpenoids from fortified controls were approximately 90% with good precision (relative standard deviations of approximately 10%).
An SPE column‐teflon sleeve assembly for in‐line retention during supercritical fluid extraction of analytes from biological matrices
Authors: Maxwell Robert J. , Lightfield Alan R. , Stolker Alida A. M.
Published: May 2005

An in‐line collector assembly designed for use in supercritical fluid extraction (SFE) vessels is described. This assembly enables solutes extracted by supercritical fluids (SF) to be retained in‐line on standard solid phase extraction (SPE) columns. The assembly consists of a standard 1 mL or 3 mL SPE column fitted into a specially fabricated Teflon© sleeve. The SPE column‐Teflon sleeve assembly is inserted into the SFE vessel followed by the sample matrix. This unit forms a leak‐tight seal with the vessel's end‐cap up to pressures of 680 bar. The choice of sorbents used in the in‐line SPE columns is dependent upon the properties of the solute in the supercritical state. After SFE is completed, the SPE column is removed and the solutes are recovered in 1–2 mL of the eluting solvent. No further clean‐up is normally required prior to chromatographic analysis of the analyte. A comparison was made of recoveries by in‐line and off‐line (after SF decompression) techniques for the SFE of three anabolic steroids in fortified chicken liver. The HPLC chromatograms of the steroids from the off‐line SPE columns were too complex for quantitation, because of coeluting artifacts, whereas chromatograms obtained from in‐line SPE columns were free from UV‐absorbing interferences and were easily quantified.
Trace‐level determination of aromatic sulfonates in water by on‐line ion‐pair extraction/ion‐pair chromatography and their behavior in the aquatic environment
Authors: Lange Frank Thomas , Wenz Michael , Brauch Heinz‐Jürgen
Published: May 2005

A new HPLC method for the fully automatic determination of aromatic sulfonates in aqueous samples is presented. The analytical procedure consists of an on‐line combination of ion‐pair extraction (IPE) and ion‐pair chromatography (IPC), both using RP‐C18 solid‐phase material and a tetrabutylammonium salt as ion pairing reagent. Experimental details and performance data are given. This method is suited for the trace‐level determination of a wide variety of benzene, naphthalene, anthraquinone and stilbene sulfonates. Detection limits for surface water using a diode‐array detector are in the sub‐ppb range. For naphthalene sulfonates a very good selectivity and minimal detectable limits of 0.02 μg/L or even lower can be achieved. So far, this method has been successfully applied to waste water, river water, bank filtrate, and water from different steps of drinking water production. The fate of several aromatic sulfonates has been studied beginning at the effluents of industrial waste water treatment plants and ending after activated carbon filtration in a water works. Napthalene‐1,5‐disulfonate (NDS, Armstrong acid) and cis‐4,4′‐dinitrostilbene‐2,2′‐disulfonate (DNS) appear in the raw water of the investigated water works and therefore have to be termed as relevant to water works. In contrast to other disulfonates NDS is extremely stable to biodegradation and ozonation and it is even desorbed from a highly loaded activated carbon filter.
Separation and determination of m‐phenoxybenzaldehyde reaction products by capillary gas chromatography
Authors: Husain Sajid , Sarma Ponnapalli Nageswara , Swamy Sankarayya
Published: May 2005

A capillary GC method employing an internal standard has been developed and successfully used for quantitative determination both of the raw materials used for the manufacture of m‐phenoxybenzaldehyde and for the components of the reaction mixtures obtained at various stages of the development of the process. A complete analysis can be performed in a single temperature programmed run.
Chromatographic methods for the analysis of crude tall‐oil
Authors: Nogueira José M. F. , Pereira José L. C. , Sandra Pat
Published: May 2005

Chromatographic methods currently used for isolation, separation, and identification of the components of crude tall‐oil have been reviewed, and their resolution and analytical methodology compared. Sample introduction by cold on‐column, rather than vaporizing, injection provides good reproducibility and operational convenience for capillary GC analysis. Size exclusion chromatography for isolation followed by capillary GC‐MS for identification, gave the best performance for analysis of acidic and dimeric compounds.
On‐Line coupling of supercritical fluid extraction with high performance liquid chromatography
Authors: Ashraf‐Khorassani Mehdi , Barzegar Mohsen , Yamini Yadolah
Published: May 2005

Supercritical fluid extraction was coupled directly with high performance liquid chromatograph. The system was evaluated for direct injection of supercritical CO2 and modified supercritical CO2 at high pressure and temperature onto a HPLC system with varying mobile phase compositions and flow rates. Injection of 9 μL supercritical CO2 onto the HPLC using methanol/water mobile phases from 100% methanol to 80% with a flow of 1.0 mL/min did not adversely affect the baseline of UV detector. However at higher percentages of water, CO2 solubility in the mobile phase decreased and caused baseline interferences on the UV detector. At higher HPLC mobile phase flow rates, supercritical CO2 was injected to higher percentages of water without any effect on the UV baseline. Also, increasing the extraction pressure or modifier concentration did not change the results. Separations of polynuclear aromatic hydrocarbons and linear alkenebenzene sulfonate test mixtures were obtained using on‐line SFE/HPLC interfaced system.
Optimized splitless injection of hydroxylated PCBs by pressure pulse programming
Authors: Vincenti Marco , Minero Claudio , Sega Michela , Rovida Costanza
Published: May 2005

Hydroxylated polychlorobiphenyls (polyhydroxy‐PCBs) are subjected to severe discrimination effect when they are introduced into a capillary gas chromatograph by splitless injection. This effect can be considerably reduced by using a pulsed pressure injection to favor sample transfer and by further programming the eluent gas pressure during the GC run. By multistep gas pressure programming, splitless injection provides analytical performances and chromatograms for (poly)hydroxy‐PCBs closely resembling those obtained by on‐column injection, whose use is generally discouraged with real environmental samples. Among the six model compounds studies, the dihydroxy congeners exhibit the best results.
A simple, inexpensive, rapid, sensitive and solventless technique for the analysis of accelerants in fire debris based on SPME
Authors: Furton Kenneth G. , Bruna Juan , Almirall José R.
Published: May 2005

The current method of choice for the extraction of flammable or combustible liquid resides from fire debris samples is passive headspace concentration using activated charcoal strips (ACS) for adsorption of the liquid residues followed by elution with carbon disulfide or other suitable solvent. Presently, we report a new technique based on headspace solid‐phase microextraction which has been successfully applied to the identification of a wide range of accelerants commonly seen in arson analysis. The SPME technique developed is simple, inexpensive, rapid, and eliminates the use of the highly flammable and toxic solvent carbon disulfide. Results using this SPME method have been directly compared to results obtained via the ACS technique for light, medium, and heavy petroleum distillates as well as gasoline. All of the accelerants studied were accurately identified by the SPME method with equal or greater sensitivity compared to the ACS method.
Application of a thermal desorption cold trap injector to multidimensional GC and GC‐MS
Authors: Nishimura Osamu
Published: May 2005

The Thermal desorption Cold Trap injector (TCT) was used as a part of modified multidimensional GC (MDGC) or MDGC mass spectroscopy (MS) systems. These systems were based on a preparative GC (GC1), an analytical GC (GC2), or GC‐MS and the TCT. The TCT was mounted on the GC2 or GC‐MS. Analysis was carried out as follows: first, the volatile compounds heart‐cut after separation on the GC1 column were adsorbed onto the Porapak Q column out of the GC1 oven. This Porapak Q column was then coupled to the TCT, and the volatile compounds adsorbed on the Porapak Q were thermally desorbed, cold trapped, and injected onto an analytical column in the GC2 or GC‐MS. Repeatability of the retention time (RT) and area % of model samples consisting of citronellol, decanol, and geranyl acetate was examined. Also, the volatile compounds present at very low concentrations in ethanol solution were concentrated on the Porapak Q column. These were injected onto the analytical column by the same method as described above, and the repeatability of the RT and area % on the chromatogram was examined. In the two experiments, the standard deviation of the RT and area % for each compound was about 0.02 and less than 2.85, respectively. A commercial geranium oil was successfully analyzed by this technique. The results indicate that this modified MDGC and MDGC‐MS system are very useful for detection and determination of compounds in complex mixtures.
Capillary GC‐MS investigation of the metabolism and excretion of oxabolone in man
Authors: Barbarulo Maria Vittoria , Buiarelli Francesca , Ciardi Massino , Giarrusso Alberto , Rosati Felice , Cartoni G. P.
Published: May 2005

The metabolism of oxabolone cipionate, 17‐(3‐cyclopentyl‐1‐oxopropoxy)‐4‐hydroxyestr‐4‐en‐3‐one, a synthetic anabolic steroid, was investigated in man, the cumulative urinary excretion and the metabolism of the compounds being studied by GC‐MS in both electron impact and chemical ionization modes. After administration by injection to volunteers, five different metabolities were detected in urine. The metabolites and the parent compound were detected in urine up to a week after administration.
The effect of electroosmotic and hydrodynamic flow profile superposition on band broadening in capillary electrophoresis
Authors: Kutter Jörg , Welsch Thomas
Published: May 2005

The effect of the superposition of electroosmotic flow and pressureinduced hydrodynamic counterflow on efficiency has been investigated for different capillary electrophoretic systems. Results are shown for 50 and 75 μm internal diameter capillaries at several voltage and counterpressure levels. Hydrodynamic counterflows were successfully applied in electrokinetic chromatography in order to delay the entry of a UV‐active pseudostationary phase, tetraphenyl porphyrintetrasulfonate, into the detection zone allowing the separation of neutral nitroaromatics. The separations are based on the weak charge‐transfer interactions between the porphyrin and the analytes.
Retention behavior of aromatic hydrocarbons and dansylamino acids in reversed‐phase liquid chromatography with cation‐exchange‐induced stationary phases
Authors: Takeuchi Toyohide , Miwa Tomoo , Hu Rongzong , Chu Jianhua
Published: May 2005

The retention behavior of aromatic hydrocarbons and dansylamino acids on cation‐exchangers modified with alkylammonium ions has been examined by microcolumn liquid chromatography. Several parameters affected the retention of analytes, involving concentration of the modifier in the mobile phase, its alkyl chain length and mobile phase composition. Stationary phases modified with a reagent having longer alkyl chains achieved better column efficiency.
Effect of ammonia on the response of the electron capture detector (ECD)
Authors: Abdel‐Rehim Mohamed , Kamel Mohamed , Hassan Moustapha
Published: May 2005

The effect of ammonia on the electron capture detector (ECD) response has been investigated. Nitrogen with different ammonia concentrations (5–20%) was used as make‐up gas. Compared to pure nitrogen, the ECD response decreased when the ammonia concentration in the make‐up gas was 5%. However, the response increased when the ammonia concentration was 20%. The response factor of 4‐chlorophenol increased 4 fold when ammonia was 20%. Also, di‐ and tri‐chlorophenols increased by 30–50%. The nitroaromatic compounds responses increased by about 2–3.7 times with 20% ammonia in the make‐up gas. The signal‐to‐noise (S/N) increased when 20% ammonia in nitrogen was used as make‐up gas compared to pure nitrogen. Also, the detector linearity increased by 50% with ammonia.
Identification of pesticide residues in real matrices by combining retention indices and specific multidetection responses
Authors: Bicchi Carlo , D'amato Angela , Binello Arianna
Published: May 2005

A previous paper reported the possibility of using the ratio between the responses of two different specific detectors to a single compound (detector response ratio, DRR) as an identification criterion for that compound, in combination with its retention index.

This article gives some applications of DRR in the identification of some pesticides in four different fruits (apples, apricots, strawberries, and peaches) in a range varying from 0.02 to 1.3 ppm, by means of their ECD/FPD DRRs. After clean‐up GC analyses were performed on a single column with dual parallel detection; a personal computer system was used for data analysis.
Pulsed discharge photoionization detector: Application to analysis of chloro alkanes/alkenes
Authors: Wentworth Wayne E. , Li Yulan , Stearns Stanley D.
Published: May 2005

A 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

The 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

Various 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

Headspace 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

A 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

Determination 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

There 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

The 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

A 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

A 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

Quantitative 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

Chiral 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

Application 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

One 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

The 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

A 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

A 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

We 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

Multidimensional 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.