bluuebunny/crossref_metadata_2025_split huggingface dataset:
Using the tools of chromatography, mass spectrometry, and automated data processing in the detection of arson
Authors: Bertsch Wolfgang , Zhang Q. W. , Holzer Günther 
Published: May 2005

AbstractThe analysis of residual accelerants in fire debris is commonly carried out by a three‐step procedure: sample preparation; separation and detection; and data interpretation. Each of these steps can be optimized individually but successful analysis requires that they are compatible with each other. The isolation of residual accelerant from fire debris requires that several methods are used to cover the range of fueis that are commonly used by arsonists. Since almost all incendiary fires are set with petroleum based fuels such as gasoline or heating oil, analysis is targeted toward hydrocarbons. Capillary column gas chromatography on apolar phases is now the overwhelmingly predominant method of separation. Data interpretation is commonly carried out by visual comparison of chromatograms.Fire debris analysis presents some unique challenges that are not often encountered in other fields. The analyte may be present at only trace levels and pyrolysis products from building materials or furnishings may dominate chromatographic patterns. Synthetic polymers may act as precursors to hydrocarbons that compete with substances typically found in petroleum based fuels. Exposure to heat and other environmental factors may also generate severe distortions in the chromatographic profiles of accelerants.Unfortunately, there is no simple solution to these problems. Methods are available to reduce some of the chemical noise introduced by interferences and thus enhance the recognizability of the target substances. Mass spectrometry, in combination with a modern data system, is the most effective approach to filter out unwanted substances. The interpretation of the analytical results is aided by scaling, side‐by‐side comparison, or stacking of chromatograms. An additional advantage of such computerized systems is the possibility of complete automation of the analysis.In this communication, we look at the interplay of chromatographic resolution, noise reduction by mass spectrometry, and automated data evaluation. Examples from model experiments and from simulated arson samples are presented.
Capillary electrophoresis: An integrated system with a unique split‐flow sample introduction mechanism
Authors: Tehrani Joe , Macomber R. , Day L. 
Published: May 2005

AbstractThe performance of an integrated capillary electrophoresis system with a novel split‐flow sample injection mechanism and special high sensitivity UV absorbance detector is described. Sample introduction into the capillary is accomplished with a standard HPLC‐type microliter syringe. The injected sample is divided proportionally between the separation capillary and an adjustable splitvent. The volume of sample introduced into the capillary can be manipulated by varying the length or the i.d. of the splitvent tubing; or the volume of sample injected. Data are presented showing reproducibility of retention time, peak height, and peak area; minimum detectability; and operation at short UV wavelengths.
Optimizing temperature program and flow rates for apillary GC analysis of EPA‐608 pesticides
Authors: Klee Matthew S. , Chang Imogene 
Published: May 2005

AbstractAn approach is described for optimizing chromatographic conditions for dual‐column analysis of U.S. EPA Method 608 pesticides. Sample throughput for environmental analysis of pesticides can be increased by performing the screening and confirmation analyses at the same time. This requires simultaneous injection, separation, and detection in a GC with dual inlets, columns, and detectors. Resolution maps for flow rate and temperature relationships of poorly resolved peak pairs for 5%‐phenyl methyl silicone and 7%‐cyanopropyl 7%‐phenyl methyl silicone capillary columns are presented. Resolution of target pesticides on the 5%‐phenyl methyl silicone column was much more sensitive to changes in flow and temperature‐ramp rates than was the 7%‐cyanopropyl 7%‐phenyl methyl silicone column. Optimal conditions resulted in a run time of approximately 20 min.
Optimized gas chromatographic analysis of natural pyrethrins and pyrethroids
Authors: Class Thomas J. 
Published: May 2005

AbstractGas chromatographic analysis of natural pyrethrins in insecticidal pyrethrum extract and in insecticide formulations is achieved by on‐column injection with hydrogen as carrier gas under constant flow and programmed pressure conditions. Short thin‐film fused silica capillaries (DB 5 and DB 1701) coupled to retention gaps separate the pyrethrins (cinerin I and II, jasmolin I and II, and pyrethrin I and II) and their analogue S‐bioallethrin (Esbiol) in less than twelve minutes at temperatures below 210°C without any discrimination, degradation or isomerization of thermally labile pyrethrin I and II. With S‐bioallethrin added as internal standard, spray and powder formulations are extracted with ethyl acetate and analyzed by gas chromatography with flame ionization detection for pyrethrum constituents, for other pyrethroids such as tetramethrin, cyphenothrin, cypermethrin, and for the commonly used synergist piperonl butoxide.
Capillary electrophoretic separation of amino acids: Fraction collection
Authors: Fujimoto Chuzo , Muramatsu Yoshie , Suzuki Misa , Jinno Kiyokatsu 
Published: May 2005

AbstractA simple method is described which enables solutes to be collected at an electrically isolated exit after they have been separated by a free solution capillary electrophoretic system. The method is illustrated by the separation of dansyl amino acids using multiple separation capillaries.
Influence of temperature control in capillary electrophoresis
Authors: Kurosu Yasuyuki , Hibi Kiyokatsu , Sasaki Toru , Saito Muneo 
Published: May 2005

AbstractWe have investigated the influence of capillary temperature on migration time and peak area and have evaluated different cooling systems. It was found that for applied voltages below 15 kV (i.e. those most frequently used) temperature control effectively improves peak area reproducibility but has less effect on migration time.
The rôle of countercurrent chromatography in the fractionation of complex mixtures
Authors: Al‐Shammary Fahad Jaber , Mian Neelofur Abdul Aziz , Mian Mohammad Saleem 
Published: May 2005

AbstractThe biologically active pricipals in nature are frequently present as only a few parts per million of complex mixtures of non‐volatile components and often have limited stability. Their isolation often requires the application of all available techniques, such as adsorption chromatography, ion exchange procedures, size exclusion techniques, and solvent partition methods consistent with their physical properties and stability. The process of countercurret chromatography is essentially liquid‐liquid chromatography in which the stationary liquid bed is retained in the column by a force field rather than by a solid supporting matrix. Adsorption effects are thereby eliminated. The technique is particularly advantageous in the preparative separation of milligram to gram quantities of polar and labile organic compounds and bio‐particulate materials such as cells and cell fragments. Virtually any twophase solvent system, either aqueous or non‐aqueous may be employed. Countercurrent chromatography (CCC) provides a convenlent alternative to adsorption chromatography for fractionation of natural products or other complex mixtures. In some cases, this high resolution method offers advantages with regard to the avoidance of contamination from solid adsorbents, versatility, and relatively inexpensive operation. The article covers some of the applications, selection of solvents, and advantages of CCC.
Capillary supercritical fluid chromatography with flame photometric detection using a large bore column SFC pumping system
Authors: Koizumi Hitoshi , Suzuki Yoshihito 
Published: May 2005

AbstractA commercially available instrument with an SFC pumping system suitable for wide bore columns (4.6 mm i.d.) has been modified for capillary supercritical fluid chromatography (CSFC) by incorporating a double‐stage flow splitter. The first flow splitter was installed in front of the sample injection valve in order to avoid a high solute split ratio. The second splitter was mounted in the column oven so that the injected sample (0.2 μL) would be split to the capillary column. In order to perform pressure programmed elution, a pressure regulating system equipped with a gradient programmer has been used. Flame photometric detection was optimized for the analysis of organosulfur compounds by CSFC. In this study, detection limits were found to be 6–14 ng and the experimentally determined exponent (n value) varied from 1.721 to 1.984 depending on the compounds tested. Sulfur‐ and phosphorus‐containing thermally labile pesticides can be chromatographed and selectively detected by using CSFC/FPD in either sulfur‐ or phosphorus mode, respectively.
Development of a new pyrolyzer for thermal desorption and/or pyrolysis gas chromatography of polymeric materials
Authors: Watanabe Chuichi , Teraishi Kuniko , Tsuge Shin , Ohtani Hajime , Hashimoto Keiji 
Published: May 2005

AbstractA new vertical microfurnace‐type pyrolyzer for thermal desorption and/or pyrolysis‐gas chromatography has been developed. The pyrolyzer consists of two independent temperature‐controlled ovens.Initially, in the desorption process, a sample cup containing the polymeric sample of interest is inserted into an oven at 300°C; the sample is then re‐positioned at the upper part of the pyrolyzer where the temperature is maintained at room temperature. The resulting vaporized components such as residual solvents and additives give a desorption chromatogram. The relative peak intensities of desorbed plasticizers in acrylonitrile butadiene‐rubber gave a relative standard deviation (RSD) of less than 2%.Subsequently, pyrolysis of the remaining polymer is conducted by dropping the sample cup into the second, pyrolyzing, oven at 55°C; at this stage the pyrogram is recorded.The resulting two chromatograms of desorbed components and pyrolysis products make it easier to characterize the polymer formulation than the complicated pyrogram obtained by an ordinary, single‐step pyrolysis.
The production of artifacts during preparation of fatty acid methyl esters from fish oils, food products and pathological samples
Authors: Moffat Colin F. , McGill Alister S. , Anderson Robert S. 
Published: May 2005

AbstractMethyl esters were synthesized from lipid extracted by a modified Bligh and Dyer technique. The lipid was saponified and the free fatty acids methylated using boron trifluoride in methanol. Butylated hydroxytoluene (BHT; 2,6‐di‐tert‐butyl‐4‐methylphenol) was added to the initial sample and to the extracted lipid prior to methyl ester synthesis.Under these conditions, the BHT was derivatized to a range of compounds, some of which can result in misinterpretation of the GC trace.Three components have been characterized by mass spectroscopy. Two of these, which eluted slightly before 16:0 on a polar column, were shown to be 2,6‐di‐tert‐butyl‐4‐methoxyphenol and 2,6‐di‐tert‐butyl‐4‐methoxy‐methylphenol. The third component, which coeluted with 15:0 on the same column, is 2,6‐di‐tert‐butyl‐4‐methoxy‐5‐hydroxyphenol.
Investigation of low mass oligomers and polymer additives from plastics. Part II: Application to polyolefin soxhlet extracts
Authors: Dilettato Dominique , Arpino Patrick J. , Nguyen Koa , Bruchet Auguste 
Published: May 2005

AbstractPolyolefin Soxhlet extracts have been investigated by capillary SFC using flame ionization detection. Separation and detection of every polymer additive (antioxidants, antistatic agents, etc.) present in the plastic were possible, sometimes in a single CSFC run. Identification of coextracted low mass oligomers and certain of the alteration products of Irganox 1010 was confirmed by GC‐MS. New methods are presented for the determination of reacted and remaining calcium stearate, used in plastics both as a stabilizer and a lubricant.
Optimization of dynamic headspace sampling for the analysis of trace volatile components of grape juice: Use of a PTV injector for intermediate trapping
Authors: Tabera Javier , Reglero Guillermo , Herraiz Marta , Blanch Gracia P. 
Published: May 2005

AbstractThe use of a programmed temperature vaporizing (PTV) injector has been evaluated for the on‐line concentration and injection of trace organic compounds either sampled from the head‐space above grape juices or purged from solution.The Simplex method was used to improve the sensitivity of the method by optimization of the experimental conditions.
Aalysis of the fatty acid composition of the lipid classes in human blood serum under normal diet and when supplemented with fish oil
Authors: Liebich H. M. , Jakober B. , Wirth C. , Pukrop A. , Eggstein M. 
Published: May 2005

AbstractTotal lipids have been extracted from human serum with chloroform–methanol 2:1 (v/v) and separated into individual classes by TLC. After transesterification the fatty acid methyl esters were analyzed by capillary gas chromatography on an FFAP column. The quantitation of ω‐3 fatty acids has been performed using internal and external standards. Internal lipid standards for each lipid class were carried throughout the entire analytical procedure. Under normal diet eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are incorporated into the lipid classes to different extents: cholesterol esters; EPA, 6.5 ± 1.9 γ/ml serum; DHA, 4.3 ± 1.9 μg/ml: phospholipids; EPA, 5.9 ± 2.7 μg/ml; DHA, 31.8 ± 8.1 μg/ml. Fish oil supplementation leads to a 4 to 6‐fold rise in EPA and to an approximately 2‐fold rise in DHA.
Micropacked capillary nucleic acid analysis
Authors: Remcho Vincent T. , McNair Harold M. 
Published: May 2005

AbstractNucleic acid compositional analysis is discussed, followed by a brief review of the current state of the technology applied in which the benefits and limitations of current methodology are enumerated. An alternative method is presented, namely the use of a micropacked capillary ion exchange column to separate nucleoside monophosphates via an anion exchange mechanism. The separated nucleotides are then quantitated by means of post‐column photodiode‐array detection. The use of a photodiode array also enables the verification of peak identity and purity by acquisition of UV spectra at any point in the separation. The technique has applications in the compositional analysis of both deoxyribonucleic acid (DNA) and ribonucleic acid (RNA).
Gas chromatographic enantiomer separation of agrochemicals using modified cyclodextrins
Authors: König Wilfried A. , Icheln Detlef , Runge Torsten , Pfaffenberger Bernd , Ludwig Peter , Hühnerfuss Heinrich 
Published: May 2005

AbstractThe enantiomers of phenoxypropionic acid type herbicides have been resolved by capillary gas chromatography employing modified cyclodextrins as chiral stationary phases. Excellent separations were obtained with columns containing a 1:1 mixture of per‐O‐pentylated and per‐O‐methylated γ‐cyclodextrin.The enantiomers of the methyl esters of mecoprop and dichlorprop were also resolved on octakis(3‐O‐butyryl‐2,6‐di‐O‐pentyl)‐γ‐cyclodextrin. On this phase the order of elution of the enantiomers was temperature‐dependent, the elution order being reversed as the temperature passed through the isoenantioselective temperature. This is the first time such behavior has been observed with cyclodextrin derivatives.The enantiomers of the polychlorinated polycyclic pesticides cis‐ and trans‐chlordane, oxychlordane, heptachlor, heptachlorepoxide, and three chiral organophosphorus pesticides could be resolved using selectively derivatized cyclodextrin derivatives.
Organochlorine residue analysis of commercial milks by capillary gas chromatography
Authors: Redondo M. Jesús , Picó Yolanda , Server‐Carrió Juan , Manñes Jorge , Font Guilermina 
Published: May 2005

AbstractThe determination of organochlorine pesticides and polychlorinated biphenyls in milks requires the use of efficient extraction methods. A rapid procedure has been developed, based on extraction of organochlorine residues from milk on to octadecylsilica solid phase extraction cartridges and elution with hexane. The addition of different organic solvents to the milk before solid phase extraction has been studied. The use of methanol to disrupt the fat globules enables almost complete recovery of the residues with minimum extraction of fatty substances.Recovery experiments were performed for eighteen compounds present at ppb levels in whole, two per cent, and skimmed milks. The average recoveries of the compounds from two per cent and skimmed milks were 73–84%; values for whole milk were lower. The residues were determined by gas chromatography using two kinds of capillary column (non‐polar and semi‐polar) and electron capture detection. The procedure shows low lipid carry over, and extraneous interferences are minimal.The method has been applied to the detection of organochlorine pesticides and nine individual polychlorinated biphenyls in commercial milks. The results obtained demonstrated the presence of very low levels of organochlorine residues in the commercial milks analyzed.
The enantioselectivity of modified cyclodextrins: Studies on interaction mechanisms
Authors: Venema Arnold , Henderiks Harmanna , v. Geest Renie 
Published: May 2005

AbstractThe separation of enantiomers of rather simple molecules, such as alkanes and alkanoic acid esters substituted at the 2‐position, has been investigated on alkylated β‐cyclodextrin stationary phases. By observing the effect of varying the substrate and the cyclodextrin alkylating agent it has been possible to propose a mechanism for the separation. The most important factors seem to be hydrophobic interactions and the ability of the cyclodextrin to change its conformation to accept the guest molecule.
The effect of treating air samples with magnesium perchlorate for water removal during analysis for non‐methane hydrocarbons
Authors: Doskey Paul V. 
Published: May 2005

AbstractA comparison has been made between two cryogenic preconcentration ‐ high resolution gas chromatography techniques for the analysis of non‐methane hydrocarbons in ambient air, one involving treatment of air samples with magnesium perchlorate to remove water, the other involving analysis without treatment. Recoveries of C1‐, C2‐, and C3‐substituted benzenes in treated samples were 80%, 50%, and 50%, respectively. Incomplete recovery of C7‐C9 n‐1‐olefins was also observed. C2‐C8 hydrocarbons and C2‐C6 n‐1‐olefins were recovered with greater than 90% efficiency. Analyses of certified audit samples containing a mixture of C2‐C8 aliphatic and aromatic hydrocarbons at the 20 ppbv level in humidified zero‐grade air indicated that the accuracy of the technique for untreated air samples was approximately 90%. The use of magnesium perchlorate for water removal cannot be recommended for the analysis of non‐methane hydrocarbons in ambient air.
Analysis of volatile aromatic compounds in gasoline‐contaminated ground water samples by static headspace sampling and high speed gas chromatography
Authors: Wang Suya , Stuart James D. , Ke Huiqiong , Levine Steven P. 
Published: May 2005

AbstractA 15 second, high speed, gas chromatographic determination has been performed on the volatile aromatic compounds in gasoline‐contaminated ground water following manual, static headspace sampling. Retention time reproducibility of the seven peaks studied ranged from 0.25 to 0.67 per cent (average relative standard deviation). Excellent linear correlations were obtained for plots of either peak height or peak area against the concentration of the compounds. Comparison was made between the results obtained from the analysis of three replicate samples of gasoline‐contaminated ground water by the high speed GC, by two field‐portable GCs, and by a laboratorybased GC. It is worthy of note that all the high speed GC analyses required for this study were accomplished in one day.
Determination of the ionization constants of weak electrolytes by capillary zone electrophoresis
Authors: Cai Jianyi , Smith Joel Tim , Rassi Ziad El 
Published: May 2005

AbstractCapillary zone electrophoresis in untreated fused silica capillaries has proved suitable for the determination of the ionization constants of weak electrolytes. Several fundamental equations relating the electrophoretic mobilities of ionized solutes to hydronium ion concentrations in the running electrolyte have been verified experimentally. The observed dependence of the electrophoretic mobilities of weak bases and ampholytes on the pH of the electrolyte showed good agreement with predicted behavior. The pKa values calculated from electrophoretic mobility data obtained by capillary zone electrophoresis were reasonably close to those reported in the literature.
Factors affecting C:H and C:N ratios determined by gas chromatography coupled with atomic emission detection
Authors: Pedersen‐Bjergaard Stig , Asp Tone Normann , Greibrokk Tyge 
Published: May 2005

AbstractAn atomic emission detector has been evaluated for the estimation of C:H and C:N ratios of compounds eluted in gas chromatography. When C:H and C:N ratios were estimated using external reference compounds, the greatest accuracy was obtained when the quantity of the reference compound was similar to that of the analyte of interest.The accuracy of the C:H and C:N ratios determined was also affected by the molecular structure of the reference compound. C:H ratios of the greatest accuracy were obtained by using reference compounds having structures similar or close to those of the compound of interest; this was not always so for C:N ratios.
Determination of organochlorine pesticide residues by solid phase extraction and dual‐column HRGC
Authors: Torreti Luigi , Simonelia Anselmo , Dossena Angelo , Torreti Emilio 
Published: May 2005

AbstractOrganochlorine pesticide residues have been extracted from samples of animal feed by a solid phase extraction clean‐up procedure using an octadecyl‐bonded column. The proposed method gave recoveries ranging from 70 to 100 % for ppb levels of the fifteeen pesticides studied. Analytes were identified by dual‐column capillary gas chromatography employing DB‐1 and DB‐1701 columns in parallel; identities were confirmed by calculation of retention indexes with the cubic spline interpolation method.
Linear temperature programmed retention indices of gasoline range hydrocarbons and chlorinated hydrocarbons on cross‐linked polydimethylsiloxane
Authors: White Curt M. , Hackett Joe , Anderson Richard R. , Kail Sally , Spock Paul S. 
Published: May 2005

AbstractThis paper describes the experimentally determined linear temperature programmed gas chromatographic retention behavior of hundreds of gasoline range hydrocarbons and chlorinated hydrocarbons on a cross‐linked 100% polydimethylsiloxane stationary phase. The retention indices of additional compounds which were not available as pure standards were measured in a synthetic gasoline after they had been positively identified by matching mass and infrared spectra.The experimentally determined retention information has been used to estimate the retention indices of additional compounds by extrapolation or interpolation of plots of carbon number against retention index of homologs.Isothermally determined Kovats retention indices of compounds measured on 100 % polydimethylsiloxane have been taken from the literature and converted to linear temperature programmed retention indices using the method of Guan et al [11]. For many of these compounds, an experimentally determined linear temperature programmed retention index was measured: agreement between experimental and converted values was excellent.In total, retention indices are presented for 480 compounds, including all possible alkylbenzenes containing ten or fewer carbon atoms, and over 150 monoenes and dienes. The effect of column pressure and the average linear velocity of the helium carrier gas on retention index and order of elution is described and discussed.