11 resultados para residual gas analysis

em Brock University, Canada


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A study was undertaken' to determine the applicability of gas liquid chromatography to the simultaneous analysis of sugars and sugar phosphates from biological samples. A new method of silylation involving dimethylsulfoxide, hexamethyldisilazane, trimethylchlorosilane and cyclohexane (1:0.2:0.1:1) which rapidly silylated sugars and sugar phosphates was developed. Subsequent chromatography on a 5% SE-52 column gave good resolution of the sugar and sugar phosphate samples. Sugar phosphates decomposed during chromatography and were lost at the 7 x 10-3 ~mole level. Acidic ethanol extraction of yeast samples revealed background contamination from the yeast sample, the culture medium and the silylation reagents which would further limit the level of detection obtainable with the glc for sugars in biological samples to the 3 x 10-4 ~mole level.

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A flow injection hydride generation direct current plasma atomic emission spectrometric (FI-HG-DCP-AES) method was developed for the determination of lead at ng.ml-l level. Potassium ferricyanide (K3Fe(CN)6) was used along with sodium tetrahydroborate(III) (NaBH4) to produce plumbane (PbH4) in an acid medium. The design of a gas-liquid separator (hydride generator) was tested and the parameters of the flow injection system were optimized to achieve a good detection limit and sample throughput. The technique developed gave a detection limit of 0.7 ng.ml-l(3ob). The precision at 20 ng.ml"* level was 1.6 % RSD with 1 1 measurements (n=l 1). Volume of sample loop was 500 |J.l. A sample throughput of 120 h"^ was achieved. The transition elements, Fe(II), FeOH), Cd(n), Co(II), Mn(n), Ni(II) and Zn(n) do not interfere in this method but 1 mg,l'l Cu(II) will suppress 50 % of the signal from a sample containing 20 ng.ml'l Pb. This method was successfully applied to determine lead in a calcium carbonate (CaC03) matrix of banded coral skeletons from Si-Chang Island in Thailand.

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TITLE: The normal co-ordinate analysis, vibrational spectra and theoretical infrared intensities of some thiocarbonyl halides. AUTHOR: J. L. Brema SUPERVISOR: Dr. D. C. Moule NUMBER OF PAGES: 89 ABSTRACT: The vibrational assignment of the five-in-plane fundamental modes of CSClBr has been made on the basis of infrared gas phase and liquid Raman spectral analyses to supplement our earlier vibrational studies. Even though the one out-of-plane fundamental was not observed spectroscopically an attempt has been made to predict its frequency. The vibrational spectra contained impurity bands and the CSClBr assignment was made only after a thorough analysis of the impurities themselves. A normal co-ordinate analysis calculation was performed assuming a Urey-Bradley force field. This calculation yielded the fundamental frequencies in good agreement with those observed after refinement of the originally transferred force constants. The theoretical frequencies are the eigenvalues of the secular equation and the calculation also gave the corresponding eigenvectors in the form of the very important LLj matrix. The [l] matrix is the transfoirmation between internal co-ordinates and normal co-ordinates and it is essential for Franck-Condon calculations on electronically excited molecules and for infrared Integrated band intensity studies. Using a self-consistent molecular orbital calculation termed "complete neglect of differential overlap" (CNDO/2) , theoretical values of equilibrium bond lengths and angleswere calcuted for a series of carbonyl and thlocarbonyl molecules. From these calculations valence force field force constants were also determined but with limited success. With the CNIX)/2 method theoretical dipole moment derivatives with respect to symmetrized internal co-ordinates were calculated and the results should be useful in a correlation with experimentally determined values.

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We have calculated the thermodynamic properties of monatomic fcc crystals from the high temperature limit of the Helmholtz free energy. This equation of state included the static and vibrational energy components. The latter contribution was calculated to order A4 of perturbation theory, for a range of crystal volumes, in which a nearest neighbour central force model was used. We have calculated the lattice constant, the coefficient of volume expansion, the specific heat at constant volume and at constant pressure, the adiabatic and the isothermal bulk modulus, and the Gruneisen parameter, for two of the rare gas solids, Xe and Kr, and for the fcc metals Cu, Ag, Au, Al, and Pb. The LennardJones and the Morse potential were each used to represent the atomic interactions for the rare gas solids, and only the Morse potential was used for the fcc metals. The thermodynamic properties obtained from the A4 equation of state with the Lennard-Jones potential, seem to be in reasonable agreement with experiment for temperatures up to about threequarters of the melting temperature. However, for the higher temperatures, the results are less than satisfactory. For Xe and Kr, the thermodynamic properties calculated from the A2 equation of state with the Morse potential, are qualitatively similar to the A 2 results obtained with the Lennard-Jones potential, however, the properties obtained from the A4 equation of state are in good agreement with experiment, since the contribution from the A4 terms seem to be small. The lattice contribution to the thermal properties of the fcc metals was calculated from the A4 equation of state, and these results produced a slight improvement over the properties calculated from the A2 equation of state. In order to compare the calculated specific heats and bulk moduli results with experiment~ the electronic contribution to thermal properties was taken into account~ by using the free electron model. We found that the results varied significantly with the value chosen for the number of free electrons per atom.

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Factors affecting the detennination of PAHs by capillary GC/MS were studied. The effect of the initial column temperature and the injection solvent on the peak areas and heights of sixteen PAHs, considered as priority pollutants, USillg crosslinked methyl silicone (DB!) and 5% diphenyl, 94% dimethyl, 1% vinyl polysiloxane (DBS) columns was examined. The possibility of using high boiling point alcohols especially butanol, pentanol, cyclopentanol, and hexanol as injection solvents was investigated. Studies were carried out to optimize the initial column temperature for each of the alcohols. It was found that the optimum initial column temperature is dependent on the solvent employed. The peak areas and heights of the PAHs are enhanced when the initial column temperature is 10-20 c above the boiling point of the solvent using DB5 column, and the same or 10 C above the boiling point of the solvent using DB1 column. Comparing the peak signals of the PAHs using the alcohols, p-xylene, n-octane, and nonane as injection solvents, hexanol gave the greatest peak areas and heights of the PAHs particularly the late-eluted peaks. The detection limits were at low pg levels, ranging from 6.0 pg for fluorene t9 83.6 pg for benzo(a)pyrene. The effect of the initial column temperature on the peak shape and the separation efficiency of the PARs was also studied using DB1 and DB5 columns. Fronting or splitting of the peaks was obseIVed at very low initial column temperature. When high initial column temperature was used, tailing of the peaks appeared. Great difference between DB! and.DB5 columns in the range of the initial column temperature in which symmetrical.peaks of PAHs can be obtained is observed. Wider ranges were shown using DB5 column. Resolution of the closely-eluted PAHs was also affected by the initial column temperature depending on the stationary phase employed. In the case of DB5, only the earlyeluted PAHs were affected; whereas, with DB1, all PAHs were affected. An analytical procedure utilizing solid phase extraction with bonded phase silica (C8) cartridges combined with GC/MS was developed to analyze PAHs in water as an alternative method to those based on the extraction with organic solvent. This simple procedure involved passing a 50 ml of spiked water sample through C8 bonded phase silica cartridges at 10 ml/min, dried by passing a gentle flow of nitrogen at 20 ml/min for 30 sec, and eluting the trapped PAHs with 500 Jll of p-xylene at 0.3 ml/min. The recoveries of PAHs were greater than 80%, with less than 10% relative standard deviations of nine determinations. No major contaminants were present that could interfere with the recognition of PAHs. It was also found that these bonded phase silica cartridges can be re-used for the extraction of PAHs from water.

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Analytical methods for the determination of trace amounts of germanium, tin and arsenic were established using hydride generation coupled with direct current plasma atomic emission spectrometry. A continuous gas flowing batch system for the hydride generation was investigated and was applied to the determination of germanium(Ge), tin(Sn), antimony(Sb) and lead(Pb) (Preliminary results suggest that it is also applicable to arsenic)As) ). With this system, the reproducibility of signals was improved and the determination was speeded up, compared with the conventional batch type hydride generation system. Each determination was complete within one minute. Interferences from a number of transition metal ions, especially from Pd(II), Pt(IV), Ni(II), Cu(II), Co(II), and Fe(II, III), have proven to be very serious under normal conditions, in the determination of germanium, tin, and arsenic. These interference effects were eliminated or significantly reduced in the presence of L-cystine or L-cysteine. Thus, a 10-1000 fold excess of Ni(II), Cu(II), Co(II), Fe(II), Pt(IV), Pd(II), etc. can be tolerated without interference, In the presence of L-cystine or L-cysteine, compared with absence of interference reducing agent. The methods for the determination of Ge, Sn, and As were examined by the analyses of standard reference materials. Interference effects from the sample matrix, for example, in transition metal-rich samples, copper, iron and steel, were eliminated by L-cystine (for As and Sn) and by LI cysteine (for Ge). The analysis of a number of standard reference materials gave excellent results of As and Sn contents in agreement with the certified values, showing there was no systematic interference. The detection limits for both germanium and tin were 20 pg ml- I . Preliminary studies were carried out for the determination of antimony and lead. Antimony was found to react with NaBH4, remaInIng from the previous determinations, giving an analytical signal. A reversed injection manner, i.e., injection of the NaBH4 solution prior to the analyte solution was used to avoid uncertainty caused by residual NaBH4 present and to ensure that an excess of NaB H4 was available. A solution of 0.4% L-cysteine was found to reduce the interference from selected transition metal ions, Co(II), Cu(II), Ni(II) and Pt(IV). Hydrochloric acid - hydrogen peroxide, nitric acid - ammonium persulphate, and potassium dichromate malic acid reaction systems for lead hydride generation were compared. The potassium dichromate - malic acid reaction medium proved to be the best with respect to reproducibility and minimal interference. Cu(II), Ni(II), and Fe(II) caused strong interference In lead determinations, which was not reduced by L-cysteine or Lcystine. Sodium citrate, ascorbic acid, dithizone, thiosemicarbazide and penicillamine reduced interferences to some extent. Further interference reduction studies were carried out uSIng a number of amino acids, glycine, alanine, valine, leucine and histidine, as possible interference reducing agents in the determination of germanium. From glycine, alanine, valine to leucine, the interference reduction effect in germanium determinations decreased. Histidine II was found to be very promising In the reduction of interference. In fact, histidine proved more efficient than L-cystine and L-cysteine In the reduction of interference from Ni(II) in the determination of germanium. Signal enhancement by easily ionized elements (EIEs), usually regarded as an interference effect in analysis by DCP-AES, was studied and successfully applied to advantage in improving the sensitivity and detection limit in the determination of As, Ge, Sn, Sb, and Pb. The effect of alkali and alkaline-earth elements on the determination of the above five hydride forming elements was studied. With the appropriate EIE, a signal enhancement of 40-115% was achieved. Linear calibration and good reproducibility were also obtained in the presence of EIEs. III

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Bovine adenovirus type 3 (BAV3) is a medium size DNA virus that causes respiratory and gastrointestinal disorders in cattle. The viral genome consists of a 35,000 base pair, linear, double-stranded DNA molecule with inverted terminal repeats and a 55 kilodalton protein covalently linked to each of the 5' ends. In this study, the viral genome was cloned in the form of subgenomic restriction fragments. Five EcoRI internal fragments spanning 3.4 to 89.0 % and two Xb a I internal fragments spanning 35.7 to 82.9 % of the viral genome were cloned into the EcoRI and Xbal sites of the bacterial vector pUC19. To generate overlap between cloned fragments, ten Hi n dIll internal fragments spanning 3.9 to 84.9 and 85.5 to 96% and two BAV3 BamHI internal fragments spanning 59.8 to 84.9% of the viral genome were cloned into the HindllI and BamHI sites of pUC19. The HindlII cloning strategy also resulted in six recombinant plasmids carrying two or more Hi ndII I fragments. These fragments provided valuable information on the linear orientation of the cloned fragments within the viral genome. Cloning of the terminal fragments required the removal of the residual peptides that remain attached to the 5' ends of the genome. This was accomplished by alkaline hydrolysis of the DNA-peptide bond. BamH I restriction fragments of the peptide-free DNA were cloned into pUC19 and resulted in two plasmids carrying the BAV3 Bam HI terminal fragments spanning 0 to 53.9% and 84.9 to 100% of the viral genome.

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Hematological status in rainbow trout, Salmo gairdneri, was examined in relation to eight combinations of three environmental fa ctors; temperature (5°, 20°C), oxygen availability «35%, >70% saturation) and photoperiod (16L:8D, 8L:16D) and evaluated by 3-factor analysis of variance. Hemog l obin and hematocrit , indicators of oxygenc arrying capacity increased significantly at the higher temperature, following exposure to hypoxia and in relation to reduced light period. Significant variations in mean corpuscular hemoglobin concentration were not detected. The effects of temperature and oxygen availability were more pronounced than that of photoperiod which was generally masked. Although oxygen availability and photoperiod did not interact with temperature, the interaction of the former fac tors was significant. Elec trophoresis revealed twelve hemoglobin isomorphs. Relative concentration changes were found in re lation to the factors c onsidered with temperature>hypoxia>photoperiod. Howeve r , in terms of absolute concentration, effects were hypoxia>temperature>photoperiod. Photoperiod effects were again masked by temperature and (or) hypoxia. Red cell +2 l eve ls of [CI ] and [Mg ], critical elements in the hemoglobin-oxygen affinity regulating system, were also significantly altered. Red cell CI +2 was influenced only by temperature ; Mg by temper ature and oxygen. No photoperiod influence on either ions was observed. Under nominal 'summer' conditions, these changes point to the likelihood of increases in oxygen-c arrying c apac ity coupled with low Hb-02 affinity adjustments which would be expected to increase oxygen delivery rates to their more rapidly metabolising tissues.

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A simple, low-cost concentric capillary nebulizer (CCN) was developed and evaluated for ICP spectrometry. The CCN could be operated at sample uptake rates of 0.050-1.00 ml min'^ and under oscillating and non-oscillating conditions. Aerosol characteristics for the CCN were studied using a laser Fraunhofter diffraction analyzer. Solvent transport efficiencies and transport rates, detection limits, and short- and long-term stabilities were evaluated for the CCN with a modified cyclonic spray chamber at different sample uptake rates. The Mg II (280.2nm)/l\/lg 1(285.2nm) ratio was used for matrix effect studies. Results were compared to those with conventional nebulizers, a cross-flow nebulizer with a Scott-type spray chamber, a GemCone nebulizer with a cyclonic spray chamber, and a Meinhard TR-30-K3 concentric nebulizer with a cyclonic spray chamber. Transport efficiencies of up to 57% were obtained for the CCN. For the elements tested, short- and long-term precisions and detection limits obtained with the CCN at 0.050-0.500 ml min'^ are similar to, or better than, those obtained on the same instrument using the conventional nebulizers (at 1.0 ml min'^). The depressive and enhancement effects of easily ionizable element Na, sulfuric acid, and dodecylamine surfactant on analyte signals with the CCN are similar to, or better than, those obtained with the conventional nebulizers. However, capillary clog was observed when the sample solution with high dissolved solids was nebulized for more than 40 min. The effects of data acquisition and data processing on detection limits were studied using inductively coupled plasma-atomic emission spectrometry. The study examined the effects of different detection limit approaches, the effects of data integration modes, the effects of regression modes, the effects of the standard concentration range and the number of standards, the effects of sample uptake rate, and the effect of Integration time. All the experiments followed the same protocols. Three detection limit approaches were examined, lUPAC method, the residual standard deviation (RSD), and the signal-to-background ratio and relative standard deviation of the background (SBR-RSDB). The study demonstrated that the different approaches, the integration modes, the regression methods, and the sample uptake rates can have an effect on detection limits. The study also showed that the different approaches give different detection limits and some methods (for example, RSD) are susceptible to the quality of calibration curves. Multicomponents spectral fitting (MSF) gave the best results among these three integration modes, peak height, peak area, and MSF. Weighted least squares method showed the ability to obtain better quality calibration curves. Although an effect of the number of standards on detection limits was not observed, multiple standards are recommended because they provide more reliable calibration curves. An increase of sample uptake rate and integration time could improve detection limits. However, an improvement with increased integration time on detection limits was not observed because the auto integration mode was used.

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Flow injection analysis (FIA) was applied to the determination of both chloride ion and mercury in water. Conventional FIA was employed for the chloride study. Investigations of the Fe3 +/Hg(SCN)2/CI-,450 nm spectrophotometric system for chloride determination led to the discovery of an absorbance in the 250-260 nm region when Hg(SCN)2 and CI- are combined in solution, in the absence of iron(III). Employing an in-house FIA system, absorbance observed at 254 nm exhibited a linear relation from essentially 0 - 2000 Jlg ml- 1 injected chloride. This linear range spanning three orders of magnitude is superior to the Fe3+/Hg(SCN)2/CI- system currently employed by laboratories worldwide. The detection limit obtainable with the proposed method was determin~d to be 0.16 Jlg ml- 1 and the relative standard deviation was determined to be 3.5 % over the concentration range of 0-200 Jig ml- 1. Other halogen ions were found to interfere with chloride determination at 254 nm whereas cations did not interfere. This system was successfully applied to the determination of chloride ion in laboratory water. Sequential injection (SI)-FIA was employed for mercury determination in water with the PSA Galahad mercury amalgamation, and Merlin mercury fluorescence detection systems. Initial mercury in air determinations involved injections of mercury saturated air directly into the Galahad whereas mercury in water determinations involved solution delivery via peristaltic pump to a gas/liquid separator, after reduction by stannous chloride. A series of changes were made to the internal hardware and valving systems of the Galahad mercury preconcentrator. Sequential injection solution delivery replaced the continuous peristaltic pump system and computer control was implemented to control and integrate all aspects of solution delivery, sample preconcentration and signal processing. Detection limits currently obtainable with this system are 0.1 ng ml-1 HgO.

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Combined gas chromatography and mass spectrometry has been used to identify unknown residues in soils (especially pesticides). The effect of U.V. light on DDT and linuron and quantitative estimation of elemental sulfur in different soils has also been carried out.