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  • 1
    Electronic Resource
    Electronic Resource
    Thermal decomposition of immobilized compounds for the generation of gaseous standard mixtures containing ammonia and amines (1997)
    Springer
    Microchimica acta 127 (1997), S. 211-217 
    Details
    ISSN: 1436-5073
    Keywords: standard gas mixtures ; calibration ; silica gel ; ammonia ; amines
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The thermal decomposition of phthalamic acid derivatives chemically bonded to the surface of silica gel was examined and utilized for the generation of single-component gaseous standard mixtures of ammonia, methylamine, diethylamine and triethylamine. The conditions of the thermal decomposition (temperature, time, diluent gas flow rate) were optimized to ensure complete liberation and rapid elution of the compounds from the bed of modified silica gel. The total amounts of these four compounds that can be released from unit mass of the modified silica gel are in the range of several mg.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01242724
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  • 2
    Electronic Resource
    Electronic Resource
    Determination of total carbon and total organic carbon from volatile air pollutants. Part I (1978)
    Springer
    Microchimica acta 70 (1978), S. 435-451 
    Details
    ISSN: 1436-5073
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Eine neue Anreicherungsmethode zur Gewinnung representativer Luftproben zur Bestimmung des Gesamtkohlenstoffgehaltes und des Gehaltes an organischem Kohlenstoff (TOC) aus flüchtigen Luftverunreinigungen wurde entwickelt. Während der Probenahme werden die flüchtigen Verunreinigungen verbrannt und nur das entstandene Kohlendioxid bei Zimmertemperatur am Molekularsieb 5A angereichert. Anschließend wird CO2 bei ca. 380° C im gereinigten Gasstrom thermisch desorbiert. Bei der TOC-Bestimmung muß atmosphärisches CO2 vorangehend aus dem Luftstrom entfernt werden und wird an einer auf 90° C erwärmten Ascariteschicht gebunden. Die durchfließenden organischen Verbindungen werden dann im dynamischen System am Körblkatalysator oxydiert, das entstandene CO2 am Molekularsieb 5A angereichert, thermisch desorbiert und einer Endbestimmung zugeführt. Organische Säuren werden gleichfalls durch den ersten CO2-Absorber gebunden. Eine Diffusionszelle zur Herstellung von Gemischen gereinigter Luft mit Dämpfen organischer Verbindungen wurde beschrieben.
    Notes: Summary A new method of collection of representative air samples for the determination of TC and TOC from volatile air pollutants has been developed. The organic substances undergo combustion and only the carbon dioxide produced is concentrated on molecular sieve 5 A at ambient temperature. The CO2 is subsequently liberated by thermal desorption at ca. 380°C in a stream of purified gas. Atmospheric CO2 must be removed first and this can be done (at the sample flow rate of 700 ml/min) by a layer of “Ascarite” heated at 90° C. Organic compounds passing through the layer are then combusted by a dynamic method utilizing Körbl catalyst and the CO2 formed is concentrated on a molecular sieve 5 A, followed by thermal desorption and final determination. Organic acids are also retained by the first CO2 absorber. A diffusion cell for preparation of the mixtures of purified air with vapours of organic compounds is described.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01197096
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  • 3
    Electronic Resource
    Electronic Resource
    Determination of total carbon and total organic carbon from volatile air pollutants. Part II (1978)
    Springer
    Microchimica acta 70 (1978), S. 473-484 
    Details
    ISSN: 1436-5073
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Die Möglichkeit einer spezifischen Entfernung von Kohlenoxid neben Dämpfen flüchtiger, organischer Verbindungen aus dem Luftstrom wurde untersucht. Zur Herstellung von CO-Luftstandardgemischen dienten gewogene Mengen Oxalsäure, die thermisch zersetzt wurden. Das im Luftstrom (700 cm3/Minute) anwesende CO wird an einer auf 90° C erhitzten Körblkatalysatorschicht von 35 mm Länge und 12 mm Durchmesser quantitativ zu Kohlendioxid oxydiert, das dann an einer erhitzten Ascariteschicht46 spezifisch gebunden wird. Bei Modellversuchen mit 16 verschiedenen organischen Verbindungen wurde festgestellt, daß der Oxydationsgrad unter den angegebenen Bedingungen 0,7–8,7% beträgt. Das entwickelte Verfahren kann somit zur praktisch spezifischen Entfernung von Kohlenoxid aus dem analysierten Luftstrom bei der Bestimmung des TOC-Gehaltes aus flüchtigen, organischen Verunreinigungen nach ihrer Oxydation Anwendung finden.
    Notes: Summary The possibility of specific removal of carbon monoxide from a stream of air in the presence of vapours of volatile organic compounds was investigated. Weighed samples of oxalic acid were pyrolyzed to obtain standard mixtures of CO with air. Carbon monoxide present in the stream of air (at the flow rate of 700 cm3/ min) is quantitatively oxidized to CO2 by a layer of the Körbl catalyst (diameter=12 mm, length=35 mm) heated to 90° C. The CO2 formed can be specifically bound by a heated layer of ascarite46. On the basis of model experiments it was concluded that under the conditions described in the paper the degree of oxidation of 16 various organic compounds ranged from 0.7 to 8.7%. Thus, the developed method can be applied as a mean of practically specific removal of CO from a stream of analyzed air in the course of determination of total organic carbon (TOC).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01197099
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  • 4
    Electronic Resource
    Electronic Resource
    Determination of total carbon and total organic carbon from volatile air pollutants. Part III (1979)
    Springer
    Microchimica acta 71 (1979), S. 1-15 
    Details
    ISSN: 1436-5073
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Die Möglichkeit einer selektiven Oxydation flüchtiger organischer Verbindungen neben Methan wurde untersucht. Methan wurde im gereinigten Luftstrom durch thermische Zersetzung eines Gemisches von CH3COONa und NaOH hergestellt. Die Oxydation des Methans im Luftstrom an einer Körbl-Katalysatorschicht ist gering und überschreitet nicht 10%, sogar bei gleichzeitiger Anwesenheit von Essigsäure, welche unter diesen Bedingungen — wie andere flüchtige, organische Verbindungen — vollständig oxydiert wird. An 16 organischen Verbindungen wurde festgestellt, daß der Oxydationsgrad≧97,5% beträgt. Die Erfassungsgrenze der entwickelten Methode zur TOC-Bestimmung ist vor allem von einer effektiven Beseitigung des sogenannten Kohlenstoffblindwertes abhängig, der durch Anwesenheit von CO2, CO und CH4 in der Luftprobe verursacht wird. Das entwickelte, selektive Oxydationsverfahren kann somit zur spezifischen Eliminierung des Einflusses von Methan auf die Bestimmungsresultate des TOC-Gehaltes aus flüchtigen Luftverunreinigungen Anwendung finden.
    Notes: Summary The possibility of selective oxidation of volatile organic compounds in the presence of methane was investigated. Thermal decomposition of a mixture of CH3COONa and NaOH was used as the source of methane introduced into a stream of purified air. Oxidation of the methane present in a stream of air on a layer of the Körbl catalyst is only slight and does not exceed 10%, even in the case of simultaneous presence of acetic acid, which is completely oxidized under identical conditions. Other volatile organic compounds also undergo complete oxidation. It was found that the degree of oxidation of 16 organic compounds is ≥97.5%. The detection limit of the developed method depends primarily on the effective removal of the so-called “carbon background” of the air sample, resulting from the presence of CO2, CO and CH4. The developed method of selective oxidation can be used for specific elimination of the effect of methane on the results of determinations of TOC in volatile air pollutants.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01197515
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  • 5
    Electronic Resource
    Electronic Resource
    Determination of total carbon and total organic carbon from volatile air pollutants (1979)
    Springer
    Microchimica acta 71 (1979), S. 345-352 
    Details
    ISSN: 1436-5073
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Die beschriebenen Methoden wurden zur Bestimmung des TC- und TOC-Gehaltes in Laboratoriumsluft erprobt. Auf Grund statistischer Auswertung der Analysenergebnisse ergibt sich, daß die Resultate der TC- und TOC-Bestimmung mit keinem konstanten und proportionellen systematischen Fehler belastet sind. Die Genauigkeit des entwickelten Verfahrens wurde für niedrige Kohlenstoffgehalte zusätzlich geprüft. Die Erfassungsgrenze kann nach Berücksichtigung des Apparaturblindwertes unter den angegebenen Bedingungen auf etwa 1 ppm Kohlenstoff geschätzt werden. Das Verfahren kann somit zur Beurteilung der Luftverunreinigung durch
    Notes: Summary Determination of TC and TOC in laboratory air by means of the method described in previous papers was undertaken. The results were evaluated statistically and were found free from constant and proportional systematic error. Additionally, the accuracy of the method was evaluated for low carbon levels. From the apparatus blank determined under these conditions the detection limit of the method is found to beca. 1 ppm of carbon. The method developed can be utilized in practice for control of the degree of air pollution by volatile organic compounds.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01197404
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  • 6
    Electronic Resource
    Electronic Resource
    Determination of total carbon and total organic carbon from volatile air pollutants (1979)
    Springer
    Microchimica acta 71 (1979), S. 317-329 
    Details
    ISSN: 1436-5073
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Das entwickelte Verfahren zur Bestimmung des TC- und TOC-Gehaltes in Form der gesamten Menge CO2 erfordert die Anwendung geeigneter Analysentechniken zur Endbestimmung dieser Verbindung. Die Möglichkeit einer Desorption des am Molekularsieb angereicherten CO2 in einem Gasstrom mit geeignetem Durchfluß erlaubt zur Endbestimmung von CO2 die Anwendung einer Reihe verschiedener Analysenverfahren. Die Anwendbarkeit verschiedener, auf Absolutverfahren und auch auf relativen Messungen beruhender Methoden wurde vergleichend untersucht. Die folgenden Methoden zur CO2-Bestimmung wurden gewählt: die Gravimetrie (klassische oder automatisierte unter Einsatz eines Wägeautomaten und einer registrierenden Waage), die Thermogravimetrie und die Coulometrie. Von den relativen Methoden wurden die Thermokonduktometrie, der Flammenionisationsdetektor (nach Umsetzung von CO2 zu Methan) und das IR-Absorptionsmeßverfahren geprüft. Die Anwendbarkeit der Methoden wurde mit Hilfe statistischer Prüfverfahren beurteilt, wobei die Präzision (SnedecorsF-Test und BartlettsU 2-Test) und die Genauigkeit (Studentst-Test) der erhaltenen Analysenwerte verglichen wurden.
    Notes: Summary The method developed based on the determination of TC and TOC in the form of the total amount of CO2 requires application of the proper techniques for the final determination of CO2. The possibility of using a stream of carrier gas at a convenient flow-rate for desorbing quantitatively CO2 concentrated on a molecular sieve permits use of a wide variety of known analytical techniques for the final determination of CO2. Various methods were compared on the basis of both absolute and calibration measurements. The absolute methods chosen were gravimetric (classical or an automated version based on application of a gravimetric automat and automatic recording balance), thermogravimetric analysis and coulometry. The calibration methods included thermal conductivity, the flame-ionization detector (after conversion of CO2 into methane) and infrared absorption. Usefulness of the methods was evaluated on the basis of comparative statistical analysis of experimental data with respect to precision (Snedecor'sF-test and Bartlett'sU 2-test) and accuracy (Student'st-test).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01197402
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  • 7
    Electronic Resource
    Electronic Resource
    Comparative study of breakthrough volumes BTV on various sorbents (1982)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 311 (1982), S. 581-584 
    Details
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Summary Breakthrough volumes on ten sorbents (Chromosorb 102, 104, 105 and 106, Porapak R and S, XAD-2, XAD-7, Tenax GC and Carbosphere) have been determined for vapours of 15 volatile organic compounds (halogenated hydrocarbons, alcohols, etc.). The volumes were determined by an indirect method employing typical chromatographic parameters such as retention volume and peak width. The method seems to be useful for preliminary estimation of adsorption capacity of various sorbents. It is not suitable, however, for the investigation of the effect of various parameters on the breakthrough volume.
    Notes: Zusammenfassung An 10 verschiedenen Sorbentien (Chromosorb 102, 104, 105, 106; Porapak R und S; XAD-2; XAD-7; Tenax GC; Carbosphere) wurden für 15 flüchtige organische Verbindungen (halogenierte Kohlenwasserstoffe, Alkohole u. a.) die Durchbruchsvolumina bestimmt. Es wurde dafür ein indirektes Verfahren mit typischen chromatographischen Parametern (Retentionsvolumen, Peakbreite) benutzt. Die Methode erscheint nützlich für die vorläufige Abschätzung der Adsorptionskapazität von Sorbentien, eignet sich jedoch nicht für die Untersuchung des Einflusses verschiedener Parameter auf das Durchbruchsvolumen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00635534
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  • 8
    Electronic Resource
    Electronic Resource
    Solventless Sample Preparation Techniques in Environmental Analysis (2000)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 297-303 
    Details
    ISSN: 0935-6304
    Keywords: Sample preparation ; gas extraction techniques ; membrane-type techniques ; water analysis ; soil analysis ; gas chromatography ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---This review focuses on the role of so-called solventless methods of sample preparation in contemporary environmental analysis. The basic classification of this group of methods as well as the principal features and advantages of the techniques in current use are discussed.
    Additional Material: 2 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    Studies on the Use of Commercial Capillary Gas Chromatographic Columns as Diffusion Denuders (2000)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 449-454 
    Details
    ISSN: 0935-6304
    Keywords: Denuders ; isolation and enrichment ; analysis ; volatile organic compounds ; partition coefficients Kfs ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---The possibility of using a piece of gas chromatographic capillary column as a tubular denuder for isolation and enrichment of organic pollutants present in air was studied. The partition coefficients (Kfs) of typical organic pollutants (benzene, chlorobenzene, toluene) between the gaseous phase and the denuder sorption layer were determined and effects of analyte concentration in the gaseous phase and gas flow rate on partitioning were studied. The partition coefficients were found to be constant in the studied range of concentration and gaseous mixture flow rate. A piece of a capillary column coated with polydimethylosiloxane can be used as a tubular denuder.
    Additional Material: 2 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    Quartz Rod Coated with Modified Silica Gel as a Source of CO and CO2 for Standard Gaseous Mixtures (1998)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 21 (1998), S. 303-307 
    Details
    ISSN: 0935-6304
    Keywords: gas chromatography ; modified silica gel ; gaseous standard mixtures ; FID calibration ; carbon monoxide and carbon dioxide ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Quartz rods coated with a thin layer of chemically modified silica gel have been used for the generation of a two-component gaseous standard mixture containing carbon monoxide and carbon dioxide. A new method based on thermal decomposition of immobilized compounds chemically bonded to the surface of silica gel has been used in the generation process. The oxalic acid moiety bonded to the glycydoxypropylsilylated surface of silica gel underwent decarbonylation and decarboxylation at 300°C, yielding carbon monoxide and carbon dioxide. On-line connection of a thermal desorber with the GC/FID enabled calibration of the detector following the process of methanization of CO and CO2. The following amounts of CO and CO2 were generated per unit length of the rod: 15.1 × 10-8 Mol cm-1 (RSD = 5.71%) for CO and 34.2 × 10-8 Mol cm-1(RSD = 5.16%) for CO2.
    Additional Material: 4 Ill.
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