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Polychlorinated biphenyls (PCBs) were formed by pyrolysis of chlorobenzenes in a HCl atmosphere. Varieties of substituted chlorobenzenes were used as model compounds to optimize the condensation reaction. Lower chlorinated benzenes produce more PCBs than that of higher ones. Up to 0.7 microg PCBs/mg 1,2,3-trichlorobenzene was produced through the condensation reaction.
Formation and decomposition behaviors of PCDD/Fs during pyrolysis of polyvinyl chloride (PVC) with CuO have been investigated. These reactions proceed simultaneously, and the rate of decomposition exceeds that of formation with further retention. More 2,3,7,8-TCDD is formed when the dechlorination of PCDD/Fs proceeds significantly. Homologue profile patterns of PCDD/Fs show that the fractions of O8CDD and H6CDFs are relatively larger within PCDDs and PCDFs, respectively. Extremely large amounts of PCDD/Fs are obtained with the long retention time at 200 degrees C. The formation of PCDD/Fs decreases drastically with increase in the molar ratio of CuO/PVC. The acceptability of thermodynamic calculations on the formation of PCDD/Fs is also investigated. The thermodynamic calculated tendency of the effect of oxygen on the formation of PCDD/Fs agrees well with the experimental results, although absolute values of the amount of PCDD/Fs are much different.
We evaluated the potential of pyrolysis-mass spectrometry (PyMS) for quantifying the binary mixed population of Streptococcus salivarius subsp. thermophilus and Lactobacillus delbrueckii subsp. bulgaricus in yoghurt. For this purpose, a new analytical approach was developed. The yoghurt was transparised and its total bacterial population was recovered by centrifugation and estimated by turbidimetric measurement. The quantity of each population (L. bulgaricus, S. thermophilus) was then estimated in the pellet by PyMS, and the data were analysed by artificial neural networks (ANNs). In parallel, streptococci and lactobacilli were numerated on SYL agar and these data were used as reference values to predict the bacterial counts of each population by PyMS. A close correlation was established between the streptococci and the lactobacilli counts on SYL agar and PyMS measurements (r(2)=0.98 for S. thermophilus and r(2)=0.96 for L. bulgaricus). Combined turbidimetric measurement and PyMS/ANNs seemed to be a powerful method for obtaining rapid counts of binary mixtures of bacteria in yoghurt.
Cell pastes and supernatant Escherichia coli samples, taken from an industrial bioprocess overproducing recombinant alpha 2 IFN were analysed using pyrolysis mass spectrometry (PyMS) and diffuse reflectance-absorbance Fourier transform infrared spectroscopy (FT-IR). PyMS and FT-IR are physico-chemical methods which measure predominantly the bond strengths of molecules and the vibrations of bonds within functional groups, respectively. They therefore give quantitative information about the total biochemical composition of the bioprocess sample. The interpretation of these hyperspectral data, in terms of the quantity of alpha 2 IFN in the cell pastes and supernatant samples was possible only after the application of the 'supervised learning' methods of artificial neural networks (ANNs) and partial least squares (PLS) regression. Both PyMS and FT-IR are novel, rapid and economical methods for the screening and the quantitative analysis of complex biological bioprocess over producing recombinant proteins. Models established using either spectral data set had a similarly satisfactory predictive ability. This shows that whole-reaction mixture spectral methods, which measure all molecules simultaneously, do contain enough information to allow their quantification when the entire spectra are used as the inputs to methods based on supervised learning. Moreover, this is the first study where FT-IR in the mid-IR range has been used to quantify the expression of a heterologous protein directly from fermentation broths and the first study to compare the abilities of PyMS and FT-IR for the quantitative analyses of an industrial bioprocess.
A case of smoke inhalation with a self-limited but prolonged febrile course, including headaches and chills, is reported. A final diagnosis of polymer fume fever was made, although the duration of fever was longer than generally has been reported with this syndrome. Pyrolysis products involved included those of polyurethane, methylene chloride, and polytetrafluoroethylene ("Teflon"). The results of toxicological testing are reported and discussed.
Tobacco smoke aerosols with fewer mutagens in the particulate fraction may present reduced risk to the smoker. The objective of this study was to test the hypothesis that the temperature at which tobacco is pyrolyzed or combusted can affect the mutagenicity of the particulate fraction of the smoke aerosol. Tobacco smoke aerosol was generated under precisely controlled temperature conditions from 250 to 550 degrees C by heating compressed tobacco tablets in air. The tobacco aerosols generated had a cigarette smoke-like appearance and aroma. The tobacco smoke aerosol was passed through a Cambridge filter pad to collect the particulate fraction, termed the smoke condensate. Although condensates of tobacco smoke and whole cigarette mainstream smoke share many of the same chemical components, there are physical and chemical differences between the two complex mixtures. The condensates from smoke aerosols prepared at different temperatures were assayed in the Ames Salmonella microsome test with metabolic activation by rat liver S9 using tester strains TA98 and TA100. Tobacco smoke condensates were not detectably mutagenic in strain TA98 when the tobacco smoke aerosol was generated at temperatures below 400 degrees C. Above 400 degrees C, condensates were mutagenic in strain TA98. Similarly, condensates prepared from tobacco smoke aerosols generated at temperatures below 475 degrees C were not detectably mutagenic in strain TA100. In contrast, tobacco tablets heated to temperatures of 475 degrees C or greater generated smoke aerosol that was detectably mutagenic as measured in TA100. Therefore, heating and pyrolyzing tobacco at temperatures below those found in tobacco burning cigarettes reduces the mutagenicity of the smoke condensate. Highly mutagenic heterocyclic amines derived from the pyrolysis of tobacco leaf protein may be important contributors to the high temperature production of tobacco smoke Ames Salmonella mutagens. The relevance of these findings regarding cancer risk in humans is difficult to assess because of the lack of a direct correlation between mutagenicity in the Ames Salmonella test and carcinogenicity.
Pyrolysis kinetics of scrap tires of passenger car and truck have been investigated thermogravimetrically under heating rates of 5, 10, 20 and 30K/min and temperature range 373-1273K in nitrogen. The results show that the initial reaction temperatures are 482-521K for the tire of passenger car and 458-511K for truck tire. Both tires exhibit similar behaviors that the initial reaction temperature decreases, but reaction range and reaction rate increase when heating rate is increased. The overall rate equation for each tire can be modeled satisfactorily by a simple one equation from which the kinetic parameters such as the activation energy (E), the pre-exponential factor (A), and the reaction order (n) of unreacted material based on Arrhenius form are determined using Friedman's method. The results show that two tires behave similarly and the average kinetic parameters of two tires are E = 147.95 +/- 0.21kJ/mol, A = (6.295 +/- 1.275)x10(10)min(-1), and n = 1.81 +/- 0.18. The predicted rate equations compare fairly well with the measured data.
Pyrolysis-gas chromatography (Py-GC) combined with on-line methylation was applied to a correlation analysis between the distributions of fatty acid components in the lipids of zooplankter individuals and those of ingested algae using principal component analysis (PCA). Py-GC in the presence of organic alkali, tetramethylammonium hydroxide (TMAH), was used to estimate the apparent distributions of fatty acid components contained in a single individual zooplankter weighing several tens of micrograms and a small sample size of ingested algae samples in the order of 10 microg. The observed fatty acid compositions were used as a database for the PCA in order to discriminate the zooplankton and ingested algae samples. The result obtained indicated that the fatty acid compositions of zooplankton individuals used in this work were significantly reflected in those of their ingested food in spite of some contribution from isomerization and/or elongation of fatty acid components during digestion of the ingested algae phytoplankton in living zooplankters.
A pyrolysis-negative ion mass spectrometry (Pyr-NIMS) is used for the monitoring of enzymatic hydrolysis of penicillin G (Pen G) to 6-aminopenicillanic acid (6-APA) and phenyl acetic acid (PAA). The high sensitivity and rapid response time of Pyr-NIMS allow its application to the simultaneously determination of these compounds. The mass to charge (m/z) values of 262, 156 and 135 of Pen G, 6-APA and PAA respectively, are used for the quantitative measurements by selected ion monitoring (SIM). The limit of detection (LOD), linearity and relative standard deviation (n=5) are 10 ng ml(-1), 100 ng ml(-1)-1000 mg ml(-1) and 1.5%, respectively The results are compared with high performance liquid chromatography (HPLC). An important advantage of the presented analytical system is the high linearity of signals without preliminary separation and recalibration. The main and interactive effects of pH, temperature and concentration of Pen G for enzymatic hydrolysis of Pen G are studied. Optimize conditions of pH (8), temperature (28 degrees C) and concentration of Pen G (12% w/v) in real samples are obtained.
We report here the application of pyrolysis-gas chromatography followed by atomic emission detection (AED) for the characterisation of Corynebacterium amycolatum and related species (i.e., C. striatum, C. minutissimum, C. xerosis and the recently described C. freneyi). This phenotypic method, which analyses the whole chemical composition of bacteria, clearly separates C. amycolatum from other species. Moreover, this C. amycolatum group is subdivided into two distinct subgroups. We cannot differentiate the C. minutissimum strains from those of C. striatum. On the other hand, C. freneyi and C. xerosis are clearly distinct from the other species.
Forty strains of luminous and non-luminous Photobacterium phosphoreum isolates from cod (Gadus morhua) and seven reference strains of psychrotolerant and mesophilic photobacteria were examined for 156 unit characters in a numerical taxonomic study. The fish strains were isolated from the intestines, from spoiled products and by using a specific detection method. The data were analysed using the similarity coefficient and the unweighted pair-group with arithmetic averages algorithm. In addition twenty-six of the fish isolates and five reference strains were analysed by Curie-point pyrolysis mass spectrometry. The mesophilic and psychrotolerant photobacteria were clearly separated in each of the analyses. Both procedures indicated that the spoilage isolates of P. phosphoreum had originated from the live fish as strains from the fish intestines and from the spoiled products were recovered in the same sub-groups. One sub-group of psychrotolerant P. phosphoreum strains, which was selected in modified atmosphere packed fish stored at low temperature, was also highlighted using each of the methods. The importance of classifying food spoilage bacteria has been shown and a simple key generated for the identification of luminous and non-luminous isolates of Photobacterium phosphoreum.
A scheme for numerical processing of pyrolysis mass spectrometry (Py-MS) data is detailed, along with methods for combining the results of conventional phenotypic and Py-MS taxonomic surveys. The importance of this combined approach in polyphasic taxonomy is emphasised; it yields data on cell composition and the nutritional and physiological interactions of strains with their environment. Large collections of strains can be surveyed rapidly and economically, yielding presumptive classifications, which may then be confirmed with a few representative strains in more demanding, difficult and expensive approaches. An objective, non-arbitrary method of establishing suitable cut-off points to delineate group structures in dendrograms is also described.
Numerical taxonomic methods were applied to the results of pyrolysis mass spectrometry (Py-MS) and conventional test reaction patterns (CTRPs) obtained with 46 strains of oral streptococci identified as representative of six species. Of these: Streptococcus gordonii strains formed a single homogeneous well-differentiated cluster both in the Py-MS and CTRP analyses; S. oralis strains were more diverse, forming 2 CTRP and 3 Py-MS clusters; S. crista, S. parasanguis and S. sanguis formed clear, but diverse and poorly differentiated clusters on the basis of CTRPs, and were poorly differentiated in the Py-MS analysis; and S. mitis strains were clearly diverse in both analyses. Peritrichously fimbriate ('tufted') S. mitis strains formed a tight cluster, well differentiated from the type strain in both Py-MS and CTRP analyses, and may represent a previously unrecognised centre of variation.
In a previously reported apparent outbreak of infection due to Acinetobacter calcoaceticus on a Regional Burns Unit in which both clinical and environmental isolates were available for study, investigations of the organisms by electrophoretic typing of surface proteins, plasmid profiling and antibiograms were inconclusive and unable to identify a single epidemic strain of the organism. The same collection of isolates has been analysed for inter-strain comparison by pyrolysis mass spectrometry (PyMS). PyMS analysis suggested that a few isolates were very different from the majority but that most of the collection comprised a group of closely similar but nonetheless distinct isolates. These isolates may well be representatives of a limited variety of strains occupying an ecological niche but not yet a single emergent strain. The ability of PyMS to detect a single epidemic strain of A. calcoaceticus when present in such a collection of isolates was demonstrated by analysis of a "constructed outbreak collection", using some of the original isolates. This study illustrates the versatility of PyMS for inter-strain comparison studies of species not yet amenable to conventional typing methods. The application of rapid, highly discriminatory, high-volume inter-strain comparison methods such as PyMS to apparent outbreaks of nosocomial infection is likely to reveal patterns of organism acquisition other than point-source transmission.
Thirteen isolates of ceftazidime-resistant Klebsiella pneumoniae from a suspected cross-infection outbreak involving patients on an intensive care unit and a haematology ward were examined in pyrolysis-mass spectrometry (Py-MS), along with eight concurrent non-outbreak-associated clinical isolates of klebsiellae as controls. Py-MS showed tight clustering of the suspected outbreak isolates, suggesting cross-infection with a single strain. Non-outbreak isolates were clearly distinct from one another and from the outbreak strain. The results confirm that Py-MS is a powerful tool for rapid strain comparison in investigations of cross-infection incidents.
The ability of pyrolysis mass spectrometry (Py-MS) to discriminate between paired groups of closely related bacteria has been examined. The technique was challenged with increasing levels of biological difference; from that between different subcultures of the same isolate of Staphylococcus aureus, through that between separate isolates of the same strain and eventually to that between different staphylococcal species and Streptococcus pyogenes. By using an analytical method in which the spectral data from any two groups can be directly compared at a time, it was shown that Py-MS was capable of measuring statistically significant differences between staphylococci and Streptococcus pyogenes, between different Staphylococcus species and between two isolates of the same strain of S. aureus from different sources. Two subcultures of the same isolate were found to be indistinguishable. The differing magnitude of the Py-MS-derived differences corresponded to the "biological differences", being much larger between staphylococci and streptococci than between staphylococcal species and only just statistically significant between isolates of the same strain from different sources. The technique described allows the assessment of the magnitude and significance of Py-MS-derived differences between any two bacterial populations.
Pyrolysis mass spectrometry (Py-MS) yields data reflecting overall cell composition. The changes in composition induced by treatment with rifampicin and ethambutol, alone and in combination, were investigated for a collection of seven strains of Mycobacterium malmoense from pulmonary infections. Two strains, both from patients that had responded to therapy with this combination, showed large changes in composition from control, untreated cultures. The difference was particularly marked for the ethambutol treated cultures. Four strains, all from patients who had failed to respond to therapy with this combination, showed minimal changes in composition for all treatments. The remaining strain also showed minimal treatment-induced change, but, for this patient, therapy with the combination had proved successful. Minimum inhibitory concentrations (MICs) were determined radiometrically. All strains showed MICs < 0.5 microgram/mL for rifampicin (sensitive) and of 8 micrograms/mL for ethambutol (resistant). MIC results did not correlate with clinical response, whereas the Py-MS results correlated with clinical response for six of the seven isolates. Py-MS may have a role in predicting effective therapy for this problem group.
Xanthomonas (Pseudomonas) maltophilia strains are frequently susceptible to aminoglycoside antibiotic and polymixin B when incubated at 37 degrees C, but resistant at 30 degrees C. Five strains showing temperature dependent resistance, and five that did not were examined by pyrolysis-mass spectrometry, a characterisation method that gives fingerprint data reflecting cell composition. Cultures grown at 30 degrees C and 37 degrees C in the absence of antibiotic were analysed. Strains showing temperature-dependent resistance exhibited a characteristic compositional difference between cells grown at the two temperatures, whereas strains not showing this type of resistance varied widely in the extent and nature of temperature-dependent differences in composition. The precise nature of the chemical differences cannot be elucidated at present, but could be determined by examining purified cell constituents.