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PubMed1988

Quantitative determination of arsenocholine and acetylarsenocholine in aquatic organisms using pyrolysis and gas chromatography/mass spectrometry.

A method for qualitative and quantitative analysis of trace amounts of quaternary organoarsenicals such as arsenocholine and acetylarsenocholine has been developed. The method is based on pyrolysis, gas chromatography/mass spectrometry and use of deuterium-labelled internal standards. Arsenocholine and acetylarsenocholine have been estimated in fish from arsenic-polluted brackish water and compared with the same species of fish from unpolluted water. The investigation also includes some fish and crustacea from marine water. The presence of arsenocholine and acetylarsenocholine in different aquatic organisms indicate the existence of a general metabolic pathway for these compounds in aquatic ecosystems.

Animals↗
PubMed2007

The combined catalytic action of solid acids with nickel for the transformation of polypropylene into carbon nanotubes by pyrolysis.

The effects of both organically modified montmorillonite (OMMT) and Ni(2)O(3) on the carbonization of polypropylene (PP) during pyrolysis were investigated. The results from TEM and Raman spectroscopy showed that the carbonized products of PP were mainly multiwalled carbon nanotubes (MWNTs). Surprisingly, a combination of OMMT and Ni(2)O(3) led to high-yield formation of MWNTs. X-ray powder diffraction (XRD) and GC-MS were used to investigate the mechanism of this combination for the high-yield formation of MWNTs from PP. Brønsted acid sites were created in degraded OMMT layers by thermal decomposition of the modifiers. The resultant carbenium ions play an important role in the carbonization of PP and the formation of MWNTs. The degradation of PP was induced by the presence of carbenium ions to form predominantly products with lower carbon numbers that could be easily catalyzed by the nickel catalyst for the growth of MWNTs. Furthermore, carbenium ions are active intermediates that promote the growth of MWNTs from the degradation products with higher carbon numbers through hydride-transfer reactions. The XRD measurements showed that Ni(2)O(3) was reduced into metallic nickel (Ni) in situ to afford the active sites for the growth of MWNTs.

Journal Article↗
PubMed1988

Detection of carcinogenic glutamic acid pyrolysis products in Worcestershire sauce by high-performance liquid chromatography.

Commercially available Worcestershire sauce was analyzed for mutagenic and carcinogenic glutamic acid pyrolysis products using high-performance liquid chromatography. These carcinogenic heterocyclic amines were found to be present in all brands of Worcestershire sauce analyzed. The identity of the carcinogens was confirmed by spectrometric analyses and the SOS umu-test. The concentrations of 2-amino-6-methyldipyrido[1,2-a:3',2'-d]imidazole (Glu-P-1) and 2-amino-dipyrido[1,2-a:3',2'-d]imidazole (Glu-P-2) in the Worcestershire sauce were 695 +/- 329 pmol/liter (mean +/- SD, n = 5) and 1,839 +/- 1,321 pmol/liter (n = 5), respectively.

Amines↗
PubMed1990

Identification of carcinogenic tryptophan pyrolysis products in human bile by high-performance liquid chromatography.

The carcinogenic tryptophan pyrolysis products 3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole (Trp-P-1) and 3-amino-1-methyl-5H-pyrido[4,3-b]indole (Trp-P-2) have been demonstrated to be present in human bile through use of a high-performance liquid chromatography (HPLC) method. The method consists of the acid-induced release of the carcinogens from bile components and their extraction with methylene chloride and subsequent quantification by HPLC. In seven subjects who had received catheterization of the bile duct and external biliarydrainage, the average amounts of Trp-P-1 and Trp-P-2 excreted daily in the bile were 408 fmol/day (n = 7) and 864 fmol/day (n = 7), respectively. In one subject, furthermore, significant daily changes of these carcinogen levels in bile and plasma were confirmed during 2 weeks of observation. These results indicate that one of the excretory pathways of these carcinogens is via bile. Our data also may suggest that Trp-P-1 and Trp-P-2 are derived from everyday foods.

Bile↗
PubMed2007

Effects of entropy on the gas-phase pyrolysis of ethyl N,N-dimethylcarbamate.

In this study, we examined the gas-phase pyrolysis of ethyl N,N-dimethylcarbamate theoretically at various theoretical levels. The reaction consists of a two-step mechanism, with N,N-dimethylcarbamic acid and ethylene as reaction intermediates. In the first step, the reaction proceeds via a six-membered cyclic transition state (TS), which is more favorable than that via a four-membered cyclic TS. Here, the contribution of entropy to the overall potential energy surface was found to play an important role in determining the rate-limiting step, which was found to be the second step when viewed in terms of the enthalpy of activation (DeltaH(not equal)), but the first step when entropy changes (-TDeltaS(not equal)) were considered. These results are consistent with experimental findings. Moreover, the experimental activation entropy can be reproduced by using the hindered rotor approximation, which converts some low vibration frequencies that correspond to internal rotational modes into hindered rotors.

Entropy↗
PubMed1981

Quantification of phencyclidine in mainstream smoke and identification of phenylcyclohex-1-ene as pyrolysis product.

Parsley cigarettes containing [3H]phencyclidine were machine smoked, and the mainstream smoke was trapped in glass wool filters. Radioactivity was extracted from these filters with chloroform. The average recoveries of radioactivity were 76, 85, 70, and 69% for cigarettes containing 3, 10, 30, and 50 mg of [3H]phencyclidine hydrochloride, respectively. TLC and GLC-mass spectrometry were employed to identify and quantify compounds in the filter extracts. Approximately one-half of the recovered radioactivity represented a pyrolysis product, phenylcyclohex-1-ene. Formation of this product involved loss of piperidine from phencyclidine. Piperidine, which was not radiolabeled, also may appear in smoke intact. The remainder of the radiolabeled material represented unchanged phencyclidine. Therefore, the percentage of [3H]phencyclidine delivered was approximately 40% of the amount smoked. This result was independent of puff frequency and quantity of phencyclidine hydrochloride smoked over the range tested. The [3H]phencyclidine delivery was compared to the quantities of [3H]-delta 9-tetrahydrocannabinol and [3H]nicotine delivered in mainstream smoke. The recovery of unchanged [3H]-delta 9-tetrahydrocannabinol from placebo marijuana cigarettes injected with a solution containing 3 mg of delta 9-tetrahydrocannabinol was 60%. Tobacco cigarettes injected with [3H]nicotine yielded 70% unchanged nicotine in mainstream smoke.

Cannabis↗
PubMed2005

Carbon isotope analyses of cellulose using two different on-line techniques (elemental analysis and high-temperature pyrolysis)--a comparison.

Even though the recent development in on-line methods for the stable isotope determination in cellulose has led to a significant increase in sample throughput and decrease in sample preparation expenditure, there still is a large potential for optimizing the analytical procedures by simultaneously measuring the isotope ratios of two or even more elements. Therefore, the main objective of this study was to answer the question whether high-temperature pyrolysis (HTP) is a suitable and reliable technique for the determination of the carbon isotopic composition of cellulose simultaneously during the well-known conventional oxygen isotope analysis. This study shows that HTP of cellulose is a technique that can produce reasonable delta(13)C values, matching the requirements of most research problems related to paleoclimatology. The reproducibility of the delta values for (13)C/(12)C is better than 0.2 per thousand. Some deficiencies of the method are related to the incomplete conversion of the organic carbon in the sample to carbon monoxide. A clear isotope effect seems to be related to the non-statistical conversion of the carbon in the cellulose to CO. The extent of this effect appears to be controlled by the relative proportion of crystallized and amorphous matter in the cellulose structure. Those deficiencies can be eliminated by using an appropriate normalization and by applying the principles of identical treatment for reference materials and samples. In general, a very good agreement is achieved for carbon isotope values determined by HTP and elemental analysis (EA).

Carbon↗
PubMed2006

Core-shell iron-iron oxide nanoparticles synthesized by laser-induced pyrolysis.

Passivated iron nanoparticles (10-30 nm) have been synthesized by laser pyrolysis of a mixture of iron pentacarbonyl and ethylene vapors followed by controlled oxidation. The nanoparticles show a well-constructed iron-iron oxide core-shell structure, in which the thickness and nature (structure similar to maghemite, gamma-Fe2O3) of the shell is found to be independent of the initial conditions. On the other hand, the composition of the core is found to change with the particle size from the alpha-Fe structure to a highly disordered Fe phase (probably containing C atoms in its structure). The dependence of the magnetic properties on the particle size, iron oxide fraction, and temperature was also investigated. In the case of smaller particles, the magnetic data indicate the existence at low temperature of a large exchange anisotropy field, the magnitude of which increases with decreasing temperature in correspondence with the freezing of magnetic moments in the oxide shell.

Ferric Compounds↗
PubMed2003

Cavitation-induced pyrolysis of toxic chlorophenol by high-frequency ultrasonic irradiation.

p-Chlorophenol (4-CP) is a recalcitrant organic pollutant that is biologically toxic in industrial wastewater. A high-frequency ultrasonic device operated at 1.7 MHz was designed and used successfully to degrade 4-CP. Iodine liberation in the KI aqueous solution confirmed that effective cavitation occurred under the high-frequency ultrasonic irradiation. No products or intermediate products were detected following the sonochemical degradation by 1H-nuclear magnetic resonance spectrum and mass spectrum after ultrasonic irradiation. It was concluded that the dominant degradation mechanism was high-temperature pyrolysis to inorganic products in ultrasonic cavities rather than free-radical oxidation.

Chlorophenols↗
PubMed2000

Pulse Pyrolysis Infrared Laser Jet Spectroscopy of Chloroketene.

The short-lived molecule chloroketene (ClHCCO) was generated by the pyrolysis of chloroacetyl chloride in a high-temperature nozzle and the infrared laser-absorption spectrum of its nu(2) fundamental band was measured between 2153 and 2161 cm(-1). The spectrum was greatly simplified by comparison with a room-temperature spectrum enabling 230 lines of the (35)ClHCCO isotopomer to be assigned and measured. A least-squares fit of these transitions yielded accurate molecular parameters for the v(2) = 1 state using ground state constants from microwave spectroscopy. The nu(2) band origin of (35)ClHCCO is 2157.19238(16) cm(-1). A comparison of simulated and experimental spectra showed that the rotational temperature of the jet spectrum was around 35 K. Copyright 2000 Academic Press.

Journal Article↗
PubMed1979

Induction of enzyme-altered islands in rat liver by tryptophan pyrolysis products.

Two new gamma-carboline derivatives, 3-amino-1,4-dimethyl-5H pyrido[4,3-b]indole (Trp-P-1) and 3-amino-1-methyl-5H pyrido[4,3-b]indole (Trp-P-2), isolated from the pyrolysis products of tryptophan, were found to be potent mutagens. When weanling rats were injected with Trp-P-1 and then given diet containing phenobarbital, they developed enzyme-altered islands in the liver. Since these islands are considered to be formed by immediate progeny of "initiated cells" and cell precursors in hepatocarcinogenesis, Trp-P-1 may well be carcinogenic in rat liver.

Adenosine Triphosphatases↗
PubMed1978

Pyrolysis gas-liquid chromatography applied to a study of variation in Arthroderma tuberculatum.

Replicates of whole colonies of four species of closely related dermatophytes were analyzed by pyrolysis gas-liquid chromatography (PGLC). The four species included fifteen strains of Arthroderma tuberculatum, and two strains each of A. benhamiae, Nannizzia gypsea and N. incurvata. Individual peaks on different pyrograms were identified as homologous with the aid of internal markers by the superimposition of pyrograms. The peak height data extracted from the pyrograms of the fungal samples were analyzed to compute average similarities between pairs of pyograms. The average was calculated with each peak weighted equally, and log weighted for its information content. The results of the cluster analyses of proximities were generally similar. Most, but not all, replicates of each strain were similar enough to be clustered together. Some strains belonging to the same species were also similar enough to be grouped in one cluster. Other strains of a single species varied sufficiently to be put in separate clusters. The nearest neighbour to each OTU (pyrogram) was always a replicate of the same strain.

Ascomycota↗
PubMed1985

Investigation by pyrolysis mass spectrometry, phage pattern and plasmid analysis of staphylococci that have reverted from 'L'-phase to bacterial phase.

No major differences have been found in series of Staphylococcus aureus strains which reverted from 'L'-phase, either by pyrolysis mass spectrometry or by phage-typing or sensitivity testing. In 'L'-phase they have been subcultured for a long time or transformed/reverted many times into/from 'L'-phase. Plasmids were lost during transformations/reversions, but there was some difference between the tetracycline-connected plasmids on the one hand and the erythromycin-connected ones on the other.

L Forms↗
PubMed1980

Acetylcholine in human placenta. Identification by pyrolysis gas chromatography/mass spectrometry and tissue levels following different modes of delivery.

Extracts from human term placentae were analyzed by pyrolysis gas chromatography (GC) combined with mass spectrometry. The only choline ester of carbonic acid whose presence could be unequivocally established was acetylcholine (ACh). The mass spectrum of its demethylated tertiary derivative dimethylaminoethyl acetate (nor-ACh) agreed entirely with that of authentic pyrolyzed ACh. The concentrations of ACh were determined in placentae obtained after vaginal or Caesarean delivery to investigate the claim that the latter resulted in tissue with higher concentrations of ACh-like activity presumably because ACh was not expended during labor and delivery. No differences inACh content were found with GC analysis. The ACh concentrations were 102 +/- 17 (n=8) nmoles/g fresh tissue (vaginal delivery) vs. 105 +/- 16 (n=6) nmoles/g (Caesarean section). The fetal membranes (amnion and chorion) and the umbilical cord contained no ACh under the analytical conditions with a limit of sensitivity of 200 pmoles ACh.

Acetylcholine↗
PubMed1979

The organic composition of the Allan Hills carbonaceous chondrite (77306) as determined by pyrolysis-gas chromatography-mass spectrometry and other methods.

The amino acid composition and the pyrolyzable organic content of the Antarctic Allan Hills meteorite (ALHA 77306.9 and ALHA 77306.17) was examined. The pyrolysis products are very similar to those of the Murchison meteorite. The identified amino acids are present at quite low levels, they are racemic and are structurally similar to those observed in the Murchison meteorite. This indicates the possible chemical synthesis of these compounds in the meteorite parent body. The Allan Hills meteorite is not detectably contaminated.

Amino Acids↗
PubMed1987

Carbohydrate profiling of bacteria by gas chromatography-mass spectrometry: chemical derivatization and analytical pyrolysis.

Carbohydrate profiling by gas chromatography-mass spectrometry is a powerful tool for the identification and detection of bacteria. Its increasing applicability in the microbiology laboratory is illustrated by three examples. In the first, differentiation of legionellae by their sugar composition was determined with alditol acetate derivatization followed by selected- ion monitoring. In the second example, a carbohydrate pyrolysis product from Streptococcus agalactiae was used to differentiate group B streptococci from other Lancefield groups after direct sampling from culture plates. The third example employed the carbohydrates rhamnose and muramic acid as chemical markers for the direct detection of bacterial cell wall degradation products in mammalian tissues. The analysis of carbohydrate markers for bacteria by gas chromatography-mass spectrometry has great potential for use in clinical identification of isolated bacteria as well as in the rapid diagnosis of bacterial infections without prior culture.

Animals↗