Carbon Tetrachloride Vapor Research Articles

Efficiency of sample introduction into inductively coupled plasma by graphite furnace electrothermal vaporization

A laboratory constructed graphite furnace electrothermal vaporizer (GF-ETV) was used for studying transport efficiencies. This device enables collection of the vaporization products that exit the central sampling hole of the horizontal graphite tube. For determination of the transport efficiency between the GF-ETV and the ICP-torch three methods were tested: (1) deposition of the aerosol particles and the vapour of certain elements by mixing the vaporization product with supersaturated steam and subsequent condensation (direct method); (2) dissolution of the deposited sample fraction from the interface components (indirect method); and (3) calculation from line intensities when applying GF-ETV and pneumatic nebulization sample introduction methods using mercury as a reference element. The latter, `mercury reference method' required 100% transport efficiency for mercury with the ETV, which could be approximated with the use of argon as carrier gas (without halocarbon addition). With a 200 cm 3/min flow rate of internal argon in the graphite tube, the transport efficiency was between 67 and 76% for medium volatility elements (Cu, Mn and Mg) and between 32 and 38% for volatile elements (Cd and Zn). By adding carbon tetrachloride vapour to the internal argon flow, the transport efficiency increased to 67–73% for the five elements studied.

Highly Sorbent Films Derived from Ni(SCN)2(4-picoline)4 for the Detection of Chlorinated and Aromatic Hydrocarbons with Quartz Crystal Microbalance Sensors

A quartz crystal microbalance (QCM) spray-coated with a Ni(SCN)(2)(4-picoline)(4) film is a sensitive detector for small aromatic (benzene, toluene) and chlorinated (trichloroethylene, perchloroethylene) vapors with a planar molecular geometry. Frequency changes during transient exposures to these vapors are rapid and reversible. In contrast, frequency changes during transient exposures to carbon tetrachloride vapor exhibit a very slow rise and decay. Impedance studies demonstrate that the QCMs are responding only to mass changes in the film. Calibration curves exhibit both linear and near-saturation responses, depending on the vapor and vapor concentration. Partition coefficients obtained from the linear response regimes of the calibration curves are in the 10 000-100 000 range, more than an order of magnitude larger than the partition coefficients for a prototypical soft polymer, poly(isobutylene). Despite the absence of evidence for crystallinity by optical or X-ray diffraction methods, the spray-coated films appear to be forming clathrates with the organic vapors. The Ni(SCN)(2)(4-picoline)(4) film is promising for the development of very sensitive and partially selective piezoelectric sensors for nonpolar or weakly polar organic vapors in air.

蒸発・凝縮の分子論的メカニズムと凝縮係数

The recent development on studies of the phase transition from a vapor to liquid phase at the vapor-liquid interface is reviewed. An experimental method by a shock tube makes it possible to determine the condensation coefficient through the measurement of the growth rate of a liquid film formed on the shock tube endwall behind a reflected shock wave. Theoretical basis for the method is given on the basis of the analysis of gas dynamics equations with kinetic boundary conditions. The condensation coefficients of methanol, acetic acid, and carbontetrachloride vapor are determined with good accuracies. Computer simulations of dynamic processes of evaporation and condensation at the interface are also introduced.

ADSORPTION EQUILIBRIUM OF CARBON TETRACHLORIDE ON DRY SOILS*

Vapor phase adsorption equilibrium of carbon tetrachloride, a priority pollutant, on dry soils was studied at 288, 293, and 298 K. Using a gravimetric adsorption apparatus, adsorption /desorption isotherms of carbon tetrachloride were generated on two different soil samples. The effects of temperature and soil characteristics were examined. Isosteric heals of adsorption were calculated and heat curves were constructed. Adsorption isotherms of carbon tetrachloride on dry soil samples were Type II, indicating formation of multilayers of adsorbate on the soil particle surface. Considerable hysteresis effects, associated with capillary condensation, were observed upon desorption. Thermal data confirmed that the adsorption of carbon tetrachloride vapor on soil was primarily physical adsorption. Heat curves showed that the soil samples had energetically heterogeneous surfaces. A positive correlation between The soil's specific surface area and its sorption capacity was observed. Clay content and pore size were also dominating factors. The experimental data were correlated by the Polanyi Potential, the BET, and the GAB models in order to provide input lo fate and transport models predicting the degradation or movement of volatile organic pollutants in soil. The BET equation gave accurate data fit, within a deviation range of 2·63-5·40%, for up to 40% of the saturation pressure. The GAB equation provided superior fit of the data for the entire relative pressure range. Absolute error percentages from the GAB model ranged from 1·77 to 5·38%. Results followed the Potential Theory satisfactorily and led to a single temperature-independent characteristic curve.

Use of artificial sweeteners to promote alcohol consumption by rats

Cirrhosis may be reliably produced in rats by exposing them intermittently to low levels of carbon tetrachloride vapour while feeding alcohol in the Lieber-DeCarli liquid diet. Providing the alcohol in drinking water that has been sweetened with sucrose is a cheaper and more convenient method but it does not yield reliable results. This study aimed to determine whether alcohol in drinking water sweetened with artificial sweeteners would give adequate alcohol intake to achieve the desired hepatic effects. Rats were fed alcohol (8% v/v) in drinking water sweetened with sucrose (5% w/v) (n = 12), or with one of the artificial sweeteners aspartame (0.025%), saccharin (0.025%) or cyclamate (0.05%) (n = 8 per agent). During the alcohol treatment the animals were exposed to carbon tetrachloride vapour, 40 ppm, six hours per night for five nights per week, over a period of 14 weeks. All groups achieved good alcohol intakes of 5-6 g/kg/day. Only one rat, in the aspartame group, became cirrhotic; all the others had varying degrees of fibrosis which did not differ significantly among the treatments. Although it was not effective in reliably achieving cirrhosis, sweetening the alcohol solution with artificial sweeteners led to reasonable alcohol intakes with resultant hepatic fibrosis, and without the high carbohydrate intake which occurs when sucrose is used.

Binary Adsorption of Vapours in Active Carbons Described by the Dubinin Equation

It is shown that the use of the Dubinin–Radushkevich isotherm within the framework of the Myers–Prausnitz theory provides a satisfactory description of the adsorption of mixtures of chlorobenzene + carbon tetrachloride vapours by active carbons. This approach can be extended to other systems and full use can be made of the advantages of Dubinin's theory. The experimental data was obtained by Headspace-GC, a rapid and reliable technique.

Collision induced hyper-Rayleigh light scattering in CCl4

Measurements of hyper-Rayleigh scattering in carbon tetrachloride liquid and vapour indicate that interaction induced contributions account for more than half of the scattered intensity from the liquid phase. The spectral characteristics of hyper-Rayleigh scattering from carbon tetrachloride are influenced by the effects of hindered rotation, orientational correlations, and dipole-induced-dipole and octupole-induced-dipole interactions, as well as the usual local field factors. The unimolecular contribution is associated with the narrow Lorentzian feature of the hyper-Rayleigh spectrum. The first hyper-polarizability β determined from the intensity of just the narrow Lorentzian feature of the liquid hyper-Rayleigh spectrum agrees with the gas phase value of β, but is 1⋅57 times smaller than the value obtained by including the entire liquid hyper-Rayleigh spectrum.

Breakthrough time of a respirator cartridge for carbon tetrachloride vapor flow of workers' respiratory patterns.

Breakthrough times of a commercially-available respirator cartridge packed with a small amount of activated carbon were determined by three different flow patterns: workers' respiratory patterns, conventional steady-state flows, and three standard patterns consisting of rectangle, sine, and triangle waves. A mechanical breathing simulator was used to reproduce the three standard wave patterns as well as the workers' respiratory patterns, which had been recorded from three workers of a paint manufacturing plant wearing a gas mask equipped with a respirator cartridge. The breakthrough test was carried out with 300 ppm carbon tetrachloride vapor at average flow rates of the respiratory and standard patterns equivalent to the steady-state flow rates. The breakthrough times determined by the workers' respiratory patterns were found to be shorter than those by a steady-state flow of the equivalent flow rate, and to be as short as those by sine and triangle wave patterns. It was considered that shorter breakthrough times in the workers' respiratory patterns could be attributed to a faster maximum inspiratory flow rate than that in the case of steady-state flow. The present results suggest that the passing time of CCl4 molecules through the thin activated carbon layer of respirator cartridge may be too short to attain an adsorption equilibrium.

Studies on kinetics of low-temperature chlorination of ZrO2 by gaseous carbon tetrachloride

Studies on the kinetics of chlorination of ZrO2. powder by carbon tetrachloride vapor in mixture with nitrogen in a low-temperature range of 650 to 825 K at different periods and partial pressures of carbon tetrachloride were carried out. The chlorination results at 650 and 675 K seem to follow a diffusion-controlled reaction model of Jander’s type: [1−(1−R)1/3]2 =k1t

Iron overload facilitates hepatic fibrosis in the rat alcohol/low-dose carbon tetrachloride model

The role of iron deposition in initiating hepatic fibrosis in iron overload disorders is not clearly established, and it is becoming increasingly recognized that iron may be interacting with other potential liver-damaging agents. The authors therefore examined the interplay of iron and alcohol in rats administered subtoxic doses of carbon tetrachloride (CCL 4) vapor at 20 ppm in customized chambers. At birth, the offspring of seven pregnant Porton rats were divided into two groups: one group was fed a normal rat chow diet and the other a diet supplemented with 3% (w/w) carbonyl iron for 10 weeks after weaning. In this latter group, the mothers were fed an iron supplement while breastfeeding. At 10 weeks, the animals from the first group (normal chow) were divided into two groups of six animals and fed a LieberDeCarli liquid diet with daily exposure to CCL 4 vapor: group 1, liquid diet + CCL 4; group 2, liquid diet + alcohol 150 kcal/I + CCL 4. The animals from the second iron-supplemented group were divided into two groups of six animals and fed a liquid diet with 3% (w/v) carbonyl iron and exposed to CCL 4 vapor for 10 weeks: group 3, liquid diet + iron + CCL 4 group 4, liquid diet + iron + alcohol supplement + CCL 4. Two animals from each group of six had a liver biopsy at 4, 6, and 8 weeks, and all animals were killed after 10 weeks of CCL 4 exposure. After the first 10-week iron loading period, the rats fed the carbonyl iron-supplemented diet had a 10-fold elevation in hepatic iron concentration. In the second 10-week (CCL 4 exposure) period, fibrosis was scored on a four-point scale in each liver biopsy and in all animals at 10 weeks. At 10 weeks, the animals exposed to iron and alcohol in addition to CCL 4 all had an established or developing cirrhosis with the development of fibrosis apparent at 4 weeks. Animals in the other groups had markedly less fibrosis, with none seen in the control group up to 10 weeks. Thus, the addition of iron to alcohol facilitates the development of fibrosis in animals exposed to subtoxic doses of CCL 4 vapor. This model should allow a more detailed analysis of the mechanism(s) underlying this process.

Iron overload facilitates hepatic fibrosis in the rat alcohol/low-dose carbon tetrachloride model

The role of iron deposition in initiating hepatic fibrosis in iron overload disorders is not clearly established, and it is becoming increasingly recognized that iron may be interacting with other potential liver-damaging agents. The authors therefore examined the interplay of iron and alcohol in rats administered subtoxic doses of carbon tetrachloride (CCl4) vapor at 20 ppm in customized chambers. At birth, the offspring of seven pregnant Porton rats were divided into two groups: one group was fed a normal rat chow diet and the other a diet supplemented with 3% (w/w) carbonyl iron for 10 weeks after weaning. In this latter group, the mothers were fed an iron supplement while breastfeeding. At 10 weeks, the animals from the first group (normal chow) were divided into two groups of six animals and fed a Lieber-DeCarli liquid diet with daily exposure to CCl4 vapor: group 1, liquid diet+CCl4; group 2, liquid diet+alcohol 150 kcal/l+CCl4. The animals from the second iron-supplemented group were divided into two groups of six animals and fed a liquid diet with 3% (w/v) carbonyl iron and exposed to CCl4 vapor for 10 weeks: group 3, liquid diet+iron+CCl4; group 4, liquid diet+iron+alcohol supplement+CCl4. Two animals from each group of six had a liver biopsy at 4, 6, and 8 weeks, and all animals were killed after 10 weeks of CCl4 exposure. After the first 10-week iron loading period, the rats fed the carbonyl iron-supplemented diet had a 10-fold elevation in hepatic iron concentration.(ABSTRACT TRUNCATED AT 250 WORDS)

Alcohol/“Low‐Dose” Carbon Tetrachloride‐Induced Cirrhosis in Rats Using Different Methods of Alcohol Feeding

Cirrhosis may be reliably produced in rats by exposing them to low levels of carbon tetrachloride vapor while feeding alcohol in the Lieber-DeCarli liquid diet. This study aimed to determine whether alternative cheaper and more convenient ways of feeding alcohol would also allow the production of cirrhosis. Animals were fed alcohol in the Lieber-DeCarli diet, in a gel diet, or by addition of alcohol + sucrose to their drinking water, and were exposed to carbon tetrachloride vapor 6 hr/night, 5 nights/week. After 12 weeks of treatment, all animals (4 of 4) receiving alcohol in the Lieber-DeCarli diet, but only two in each of the gel and drinking water groups, were cirrhotic. The variable results with the gel diet may be due to loss of alcohol by evaporation from the gel. Alcohol intake in the group receiving alcohol in drinking water was greater than in those receiving Lieber-DeCarli diet. We suggest that the increased carbohydrate intake due to addition to sucrose to the water exerted a protective effect on the liver.

Atomization efficiencies in halocarbon-loaded acetylene-air flames—I. Monochlorides of readily volatilized elements

Carbon tetrachloride vapour was introduced with a carrier air stream into the mixing chamber of an acetylene-air flame while nebulizing aqueous solutions of several metal salts. The atomic absorption signal was measured under increasing flow rate of the halocarbon vapour at constant fuel-to-oxidant ratio, and the latter parameter was also varied in separate experiments. By applying the theory developed by Sugden and Bulewicz, the exclusive formation of monochlorides in the gaseous phase (presented here, in Part I) and the additional formation of hydroxychlorides and dichlorides (presented in Part II) could be elucidated. From the decrease of the signal measured for the alkali elements of known monochloride dissociation constants and dissociation energies, the temperature and the chlorine concentration present in the observed flame zone could be calculated. It is inferred that only 19% of the total halogen introduced is converted to HCl and Cl species in a slightly fuel-rich flame. The signal depression is stronger in a fuel-lean flame of higher monoatomic chlorine concentration for those elements which have a relatively efficient atomization under these flame conditions. An increase of the electron concentration resulting from the introduction of the halocarbon in an alkali-containing flame was deduced from the experimental findings, in agreement with earlier observations.

The pathology of liver injury induced by the chronic administration of alcohol and 'low-dose' carbon tetrachloride in Porton rats.

We have previously established a model for micronodular cirrhosis by feeding Wistar rats alcohol, in the Lieber-DeCarli liquid diet, and exposing them to 'low-dose' carbon tetrachloride (CCl4) vapour for 10 weeks. This study reports the spectrum of liver pathology seen in male Porton rats exposed to 'low-dose' CCl4 vapour 5 nights/week, 6 h/night while being fed alcohol (300 kcal/L) in the Lieber-DeCarli diet. Micronodular cirrhosis developed in all animals after 5-7 weeks of treatment. The simultaneous administration of silymarin, a putative hepatoprotective agent, in the liquid diet, did not alleviate or prevent the chronic liver injury. The histopathological features of the liver injury are described, with particular emphasis on the presence of small epithelial cells ('progenitor or stem cell'), which appear to be playing a role in liver regeneration.

Biological Monitoring of Workers Exposed to Carbon Tetrachloride Vapor

Abstract Occupational exposure to carbon tetrachloride was studied by analysis of environmental air, blood, and urine from 55 workers operating in two chemical plants where carbon tetrachloride was used. For the measurement of environmental concentration of carbon tetrachloride (Ci), the ambient air was sampled using personal passive dosimeters. The activated charcoal was de-sorbed with carbon disulfide and injected into a gas cromatograph-mass spectrometer (GC-MSD). The biological monitoring of exposed workers was conducted by determining the concentration of carbon tetrachloride in blood and urine. Urine and blood concentrations of carbon tetrachloride were determined by headspace analysis using GC-MSD. Significant correlations were found between the environmental carbon tetrachloride concentration and the blood and urinary concentrations. The use of a regression equation between Cu (ng/L) and Ci (mg/m3) (Cu = 125.7 × Ci + 56.2) result in a value of Cu corresponding to threshold limit value-time-weighte...

ICP-AES detection of silicon carbide impurities volatilized in a graphite furnace with the use of carbon tetrachloride vapour

The analytical capability of high-temperature halogenation with carbon tetrachloride vapour in a graphite furnace was investigated for silicon carbide powder with known chemical composition and particle size. Intensity vs heating time curves were determined for analytical lines of Al, B, Ba, Ca, Cr, Cu, Fe, Mg, Mn, Ti, V and Si constituents, volatilized with and without the presence of CCl4 vapour in the furnace atmosphere. Igniting 10 mg SiC at 2100 °C for 60 s in chlorinating atmosphere, the evaporated fraction of most of the constituents was higher than 90% (for Al about 50%). The line intensity vs sample mass (4–26 mg) relationships were linear for all impurities studied, while the intensity of silicon line showed a relatively small change with the sample mass. BEC (background equivalent concentration) values for this solid sampling technique (10 mg loaded sample) were 2–20 fold lower than those calculated for the conventional solution sample introduction method.

Hepatic fibrosis and cirrhosis after chronic administration of alcohol and “low-dose” carbon tetrachloride vapor in the rat

Rats were exposed to carbon tetrachloride vapor, 5 days/wk, 6 hr/day, for periods of 5 or 10 wk at a concentration that by itself caused only fatty change with minimal liver cell necrosis and no fibrosis. The same carbon tetrachloride exposure when given in association with chronic alcohol feeding resulted in extensive hepatic fibrosis at 5 wk and established micronodular cirrhosis at 10 wk. The periodicity of the exposure profile was chosen to simulate that of human exposure to environmental toxins, albeit at a higher dose than would be permitted in the workplace. The development of significant liver injury in this animal model raises the possibility that some chronic liver injury in humans may be due to alcohol potentiation of other hepatotoxins present in the environment at subtoxic levels. (Hepatology 1991;13:815-819).

Hepatic fibrosis and cirrhosis after chronic administration of alcohol and “low-dose” carbon tetrachloride vapor in the rat

Rats were exposed to carbon tetrachloride vapor, 5 days/wk, 6 hr/day, for periods of 5 or 10 wk at a concentration that by itself caused only fatty change with minimal liver cell necrosis and no fibrosis. The same carbon tetrachloride exposure when given in association with chronic alcohol feeding resulted in extensive hepatic fibrosis at 5 wk and established micronodular cirrhosis at 10 wk. The periodicity of the exposure profile was chosen to simulate that of human exposure to environmental toxins, albeit at a higher dose than would be permitted in the workplace. The development of significant liver injury in this animal model raises the possibility that some chronic liver injury in humans may be due to alcohol potentiation of other hepatotoxins present in the environment at subtoxic levels.

Vibrational structure in the laser excitation spectrum of nickel dichloride at 360 nm

Nickel dichloride has been formed “cold” in the vapor phase by heating the solid to about 750°C, entraining the vapor in a high pressure of argon and expanding it supersonically through a small hole into a vacuum chamber. The laser excitation spectrum of the sample prepared in this way has been recorded in the region of 360 nm. Under these conditions, it is possible to resolve both vibrational and rotational fine structure. The same spectrum was recorded when carbon tetrachloride vapor was passed over the hot metal and expanded through the nozzle. Some “hot” bands have been identified by dispersing the fluorescence with a small monochromator. Virtually no chlorine isotope structure could be identified, even when isotopically enriched samples were used. A partial analysis of the vibrational structure has been achieved in which several progressions in the symmetric stretching vibration have been identified. These progressions are consistent with a value for v ̃ 1 of 360 cm −1 for the lower electronic state and 345 cm −1 for the upper electronic state. The complications in the observed spectrum may be caused by two or more upper electronic states being involved in the band system.

Non-equilibrium condensation of water and carbontetrachloride vapour in a shock-tube

This paper deals on molecular levels with the condensation parameter and the condensation coefficient (sticking probability) of both water and carbontetrachloride vapour. The time-dependent thickness of a liquid film on a shock-tube endwall behind a reflected shock wave is measured by an optical method based on multiple reflections of light in the film. The measured thickness of the film is compared with theoretical one which is a solution of gasdynamics equations under molecular gasdynamical boundary conditions. The condensation parameter and the condensation coefficient of the above two kinds of vapour are determined from the comparison between experiment and theory. They are reasonably explained by the transition state theory on the basis of statistical mechanics of gases and liquids.