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  • 11
    Electronic Resource
    Electronic Resource
    Springer
    Fresenius' journal of analytical chemistry 360 (1998), S. 816-819 
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A total of 19 PCB congeners were determined in muscle of 2 European roach (Rutilus rutilus) and in muscle and liver of 3 pike (Esox lucius) of a small rural lake in the southern Black Forest (Germany) to examine the biomagnification in freshwater fish. The lake is known for a relatively high PCB contamination of its sediments due to past local emissions. The presence of a structure dependent biomagnification in these freshwater fish of two different trophical levels is confirmed. The relative contents of PCB congeners with vicinal H-atoms in m,p- and to a lesser extent, o,m-positions become smaller from roach to pike indicating a stronger induction of PCB metabolizing isoenzymes in the predatory fish. This could also be shown by application of the metabolic slope concept.
    Type of Medium: Electronic Resource
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  • 12
    Electronic Resource
    Electronic Resource
    Springer
    Fresenius' journal of analytical chemistry 364 (1999), S. 91-99 
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The overall probability of the formation of arylalkyl nitrates is low in comparison to alkyl nitrates. However, measurable amounts of arylalkyl nitrates are found in traffic influenced air. It is reported here an analytical protocol based on high-volume sampling, adsorption liquid chromatography as a step in sample preparation, and high-resolution gas chromatography with electron ionization mass selective detection (HRGC/EI-MSD) as well as high-resolution gas chromatography with negative chemical ionization mass selective detection (HRGC/NCI (methane)-MSD) for the determination of arylalkyl nitrates as atmospheric constituents in urban air. The synthesis of arylalkyl nitrates as reference compounds is described. The arylalkyl nitrates can be selectively detected by the fragments M-46 (M-NO2) and M-48 (M-NO2-2H) in HRGC/NCI(methane)-MSD. In EI(70 EV)-MSD the dominating ions are at 46, 77, 91 and 105 u, which correspond to the NO2 + and the phenyl, benzyl, and ethylbenzene fragments, respectively. The molecular ions are missing in (NCI-methane)-MSD and are of medium intensity in EI-MSD. Phenylethyl and phenylpropyl nitrates elute in GC in the range of n-octyl to n-dodecyl nitrate. The following arylalkyl nitrates have been identified in urban air: Benzyl nitrate (PhC1) and the three xylyl nitrates (M-PhC1), phenylethyl-1-nitrate (1Ph1C2), phenylethyl-2-nitrate (1Ph2C2), phenyl-n-propyl-1-nitrate (1Ph1C3), and phenyl-n-propyl-2-nitrate (1Ph2C3). Benzyl nitrate is the dominating compound in this group and is found at levels of 10–300 ng/m3 in urban air.
    Type of Medium: Electronic Resource
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  • 13
    Electronic Resource
    Electronic Resource
    Springer
    Fresenius' journal of analytical chemistry 359 (1997), S. 561-564 
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Polychlorinated benzonitriles (PCBN) are products of combustion chemistry and can be emitted from municipal waste incinerators. Their possible relevance to environmental chemistry has not previously been described, with the exception of the herbicide 2,6-dichlorobenzonitrile. The isomer-specific separation and detection of the 19 PCBN congeners is performed by HRGC-ECD and HRGC-MSD. Commercially unavailable congeners were synthesized from chlorinated anilines and benzaldehydes. Retention data on three different stationary phases are given. Structure-retention relationships are discussed. A structure-specific systematic numbering of the 19 PCBN congeners is suggested.
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  • 14
    Electronic Resource
    Electronic Resource
    Springer
    Fresenius' Zeitschrift für analytische Chemie 215 (1965), S. 305-315 
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Zur Herabsetzung der Nachweisgrenze von Organohalogeniden in der Dünnschichtchromatographie durch Fluorescenznachweise wurden 24 fluorescierende Verbindungen verschiedener Stoffklassen untersucht. Durch Sprühreagentien mit N,N,N′,N′-Tetraäthyl-benzidin, N,N-Dimethylamino-fluoranthen, N-Methyl-carbazol, 3-Amino-pyren, Rhodamin B oder Resorufin in z.B. Aceton/dest. Wasser werden nach Bestrahlen der Dünnschichtplatte (1–15 min) mit UV-Licht (254 oder 350 nm) Substanzmengen bis zu 20 ng von polychlorierten Insecticiden (z.B. Aldrin®, Telodrin®, Thiodan®) nach dünnschichtchromatographischer Trennung aufSilicagelGMerck oder Aluminiumoxid G Merck nachgewiesen. Die Empfindlichkeit der Nachweise läßt sich in erster Linie auf geringe Fluorescenzindicatorkonzentrationen (10−2-10−3%) und auf den Zusatz eines geeigneten hochsiedenden Lösungsmittels (z.B. Dimethylformamid) zum Sprühreagens zurückführen.
    Notes: Summary In order to reduce the limit of detection of organohalides following thinlayer chromatography 24 fluorescent substances of various types were studied. The lowest amount of polychlorinated insecticides (e.g. Aldrin, Telodrin, Endosulfan) to be detected on silicagel G Merck or Al2O3 G Merck was 20 ng. The spots were made visible by spraying the thin-layer with fluorescent reagents containing 4.4′-bis-diethylamino-diphenyl, 3-dimethylamino-fluoranthene, 9-methyl-carbazole, 3-amino-pyrene, rhodamine B, or resorufin in e.g. acetone/dest. water. After irradiating the plates with ultraviolet light at 2536 or 3500 Å for 1–15 min the spots showed fluorescence or quenching. The sensitivety of detection is caused primarily by the low concentration of the fluorescent indicator (10−2-10−3%) and by adding suitable solvents of high boiling point (e.g. dimethyl formamide) to the spray solution.
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  • 15
    Electronic Resource
    Electronic Resource
    Springer
    Fresenius' Zeitschrift für analytische Chemie 346 (1993), S. 800-804 
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The concept of the molar response (MR) in HRGC/EI-MS has been checked for naphthalene and three chlorinated naphthalenes: 1-chloronaphthalene, 1,2,3,4-tetrachloronaphthalene and octachloronaphthalene. The molar response factors increase with increasing degree of chlorination. When the ion yield is normalized for the ionization cross section Q of the molecule, a constant value of injected molar mass to signal intensity is obtained for naphthalene up to octachloronaphthalene. It allows to quantify all chlorinated naphthalene congeners on the basis of one or two reference compounds. This has been done for the ClxN (x=1−8) in a technical mixture of polychlorinated naphthalenes (Halowax 1014) and in a MWI fly ash sample. The latter one had a concentration of 520 ng/g dry weight for the ClxN (x=1−8).
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  • 16
    Electronic Resource
    Electronic Resource
    Springer
    Fresenius' Zeitschrift für analytische Chemie 348 (1994), S. 226-239 
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Fourteen polychlorinated biphenyl (PCB) congeners were quantified in air samples of the tropospheric boundary layer of the Atlantic Ocean. The samples were taken on the German research vessel “Polarstern” during north-south cruises across the Atlantic Ocean (1990, 1991), and on the Capo Verde islands in the North Atlantic Ocean (1992). Values for the sum of PCB were between 48 pg/m3 (values for the seven indicator congeners were [in pg/m3]: PCB 28: 1.3; PCB 52: 5.0; PCB 101: 3.0; PCB 118: ≤0.5; PCB 138: 1; PCB 153: 1; PCB 180: 〈0.2) in the Westwind Belt of the eastern North Atlantic and 22 pg/m3 (values for the seven indicator congeners were [in pg/m3]: PCB 28: 2.3; PCB 52: 3.4; PCB 101: ≤0.5; PCB 118: 〈0.2; PCB 138: 〈0.2; PCB 153: 〈0.2; PCB 180: 〈0.2) in the Westwind Belt of the central South Atlantic. Up to 385 pg/m3 (values for the seven indicator congeners were [in pg/m3]: PCB 28: 2.6; PCB 52: 11.7; PCB 101: 28.4; PCB 118: 9; PCB 138: 21; PCB 153: 18; PCB 180: 5.5) were measured of the coast of South Patagonia. A difference depending on latitude and on terrestrial influenced air masses between the lower and the higher chlorinated congeners was observed. The levels of three- and tetrachlorinated congeners were highest in the Trade Wind regions. The contents of the higher chlorinated congeners had maxima in samples influenced by continental air masses. A correlation of the levels of the lower chlorinated congeners in air over the South Atlantic with the surface water temperature and thus with the temperature dependent gas/water partition coefficient Kgw was observed.
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  • 17
    Electronic Resource
    Electronic Resource
    Springer
    Fresenius' Zeitschrift für analytische Chemie 348 (1994), S. 583-589 
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The separation of a-hexachlorocyclohexane and of all eight possible pentachlorocyclohexene isomers into their enantiomers by high-resolution gas chromatography and electron capture detection was achieved by using permethylated β-cyclodextrin in DB 1701 (Cyclodex-B, J & W) as chiral stationary phase. The first step in the metabolism of 1,2,3,4,5,6-hexachlorocyclohexane (HCH) is the formation of 1,3,4,5,6-pentachlorocyclohexene-1 (PCCH). Various degradation experiments were carried out with α-, β-, γ-, and δ-HCH. Whereas β-HCH gave no degradation products, the isomers α-, γ-, and δ-HCH degraded into various PCCHs and trichlorobenzenes, when using pyridine as dehydrochlorination reagent in xylene at 60°C. Isomerization into other HCH isomers was observed only for δ-HCH. Enantioselective dehydrochlorination was observed for a- and γ-HCH using the alkaloid (−)-brucine, R-(+)- or S-(−)-a-phenylethylamine as chiral base.
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  • 18
    Electronic Resource
    Electronic Resource
    Springer
    Fresenius' Zeitschrift für analytische Chemie 348 (1994), S. 590-594 
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The isolation of high-purity chlorophyll a was achieved by HPLC using a micro-preparative column with a diol-phase (Polyol, Si 100, 5 μm) in normal-phase mode. The procedure included the extraction of photosynthetic pigments from the leaves of stinging nettles and their partial purification as dioxane-water-chlorophyll-aggregates prior to the isolation by micro-preparative HPLC. Freeze-drying resulted in a flaky chlorophyll a, which was free of water. Each step of isolation was controlled by using an analytical HPLC-column with a diol-phase and a photodiode array detector. Synthesized metalloporphyrins (metal(II)-ion = Mg2+, Zn2+, Cu2+, Ni2+) with structures analogous to chlorophyll were also isolated by means of the micro-preparative HPLC-column containing a diol-phase. The purity of the obtained porphyrins was monitored with an analytical HPLC-column.
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  • 19
    Electronic Resource
    Electronic Resource
    Springer
    Fresenius' Zeitschrift für analytische Chemie 348 (1994), S. 595-597 
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract An homologous series of eight 2,4,6-trichlorophenyl alkyl ethers (TCPE) was synthesized. The TCPE has been conceived to be used as retention index markers in the gas chromatography with the atomic emission detector (AED), the electron capture detector (ECD) and the mass spectrometric detector (MSD). On the basis of the TCPE, the retention indices of 28 polychlorinated biphenyls have been determined using the ECD, a 95% dimethyl 5% phenyl polysiloxane phase and six different temperature programs.
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  • 20
    Electronic Resource
    Electronic Resource
    Springer
    Fresenius' Zeitschrift für analytische Chemie 350 (1994), S. 384-394 
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Nitric acid, HNO3, and nitrous acid, HNO2, are forming stable esters with alcohols, the alkyl nitrates and alkyl nitrites. Both groups of compounds are used as fuel additives, explosives and pharmaceuticals. Alkyl nitrates are also formed as complex mixtures during incomplete combustion and the abiotic transformation of alkanes, alkenes and aldehydes in air. Organic nitrates can be assigned to anthropogenic and natural sources alike. Here the synthesis of reference mixtures of alkyl nitrates is described starting with alcohols, alkyl bromides, alkyl iodides or alkanes, respectively, sampling techniques in air analysis, and the separation of alkyl nitrates and alkyl dinitrates by high resolution capillary gas chromatography using various stationary phases and electron capture (HRGC/ECD) as well as mass spectrometric detection (HRGC/MSD). A highly selective detection mode for alkyl nitrates and alkyl di- and trinitrates — in general in the presence of other organic trace compounds — is the single ion monitoring of 46 amu in GC/MS. The separation and occurrence of alkyl- and phenyl-alkyl nitrates in polluted air is reported using capillary gas chromatography with electron capture and ion trap MS detection. The reaction of alkanes with nitric acid at room temperature simulates in a good approximation the pattern of alkyl nitrates formed in air chemistry.
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