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In this study, trends in the prediction of acentric factors of halogenated alkanes (HAs) were investigated using two group contribution techniques. The examination of discrepancies between predicted and experimental values for both methods served to delineate the precision and constraints of these prediction techniques. It was observed that while predictions for certain compounds conformed closely to experimental data, others manifested substantial deviations, thereby accentuating the intricacies inherent in predicting acentric factors. The discourse extended to practical implications for applications within the realm of engineering, particularly emphasizing the imperative for the refinement of methods and the conduct of comparative analyses to enrich predictive accuracy. The academic contributions of this investigation are notable for the advancement of predictive methodologies over traditional laboratory procedures in addressing environmental concerns associated with halogenated hydrocarbons. [ABSTRACT FROM AUTHOR]

This study investigates the effects of trifluoromethane (CHF 3) and pentafluoroethane (C 2 HF 5) content on maximum explosion overpressure and maximum rate of pressure rise by changing the equivalence ratio. Then, the critical content of hydrogen explosion inhibition is measured. The inhibition and enhancement mechanisms are analyzed using thermodynamics and reaction kinetics. The results indicate that both sub-inhibitory CHF 3 and C 2 HF 5 enhance hydrogen explosion on the lean and stoichiometric sides, and C 2 HF 5 exhibits stronger enhancement. As the equivalence ratio increases, CHF 3 and C 2 HF 5 directly reduce the maximum explosion overpressure, while C 2 HF 5 shows stronger inhibition. The maximum rate of pressure rise of different equivalence ratios decreases directly with increasing CHF 3 and C 2 HF 5 content. For the same equivalence ratio, the critical content of explosion inhibition of C 2 HF 5 is lower than that of CHF 3. Additionally, R31, R829, R927, and R944 contribute to explosion enhancement by consuming CO, producing [H], or releasing heat, while R824, R830, and R861 for CHF 3 as well as R830, R988, R1097, and R1099 for C 2 HF 5 inhibit hydrogen explosion intensity. • CHF 3 and C 2 HF 5 enhance hydrogen explosions on the lean side. • Production of CO is related to the explosion enhancement caused by CHF 3 and C 2 HF 5. • Critical content of hydrogen explosion inhibition of C 2 HF 5 is lower than that of CHF 3. [ABSTRACT FROM AUTHOR]

• A novel NTD was developed using an amide-based COF and characterized. • The COF-packed NTD was coupled with GC-FID for the microextraction analysis of HHCs in the air for a first time. • The NTD-GC-FID exhibited high adsorption capacity and thermal stability. • The approach provides a solvent-free method for assessing exposure to hazardous hydrocarbons. • TMC-BD COF@SiO 2 could be considered as a new adsorbent in air pollutant sampling. A needle trap device (NTD) was developed using an amide-based covalent-organic framework (COF), chemically bonded to silica nanoparticles. The NTD was coupled with gas chromatography-flame ionization detection (GC-FID) and employed for the headspace microextraction analysis of halogenated hydrocarbons (HHCs) in the air. The adsorbent was characterized using Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction analysis (XRD), transmission electron microscopy (TEM), and field-emission scanning electron microscopy (FE-SEM) techniques. Optimal values for the experimental variables were assessed using response surface methodology (RSM) with a central composite design (CCD), thereby reducing the number of experiments, material consumption, costs, and time. The optimal values for desorption time and temperature were obtained 5 min and 260 °C, respectively. Breakthrough volume (BtV) was studied over the range of 0.5 - 3 times the occupational exposure limit (OEL) and its optimal value was found to be 1200 mL. The optimal sampling temperature and relative humidity (RH) were obtained 20 °C, and 15 %, respectively. The limits of detection (LODs) and limits of quantification (LOQs) were ranged from 0.013 to 0.077 μg l -1 and 0.041 to 0.21 μg l -1, respectively, with a linear dynamic range (LDR) of 0.04 to 100 μg l -1. The method's repeatability and reproducibility (RSD %) were observed over the ranges of 5.3 - 6.4 % and 4.7 -6.9 %, respectively. A statistically validated agreement was observed between the NTD-GC-FID method and the NIOSH 1003 standard procedure for the sampling and determination of HHCs in real workplace air samples, demonstrating the reliability and accuracy of the developed approach. [Display omitted] [ABSTRACT FROM AUTHOR]

Halogenated hydrocarbon organic tracer is a kind of chemical tracer, which has the characteristics of less adsorption on the bottom surface and easy to be detected. In this resear ch, gas chromatography-mass spectrometry (GC/MS) was applied to analyse p-fl uoro bro mo benzene, bromobenzene, bromocyclohexane, p-dichlorobenzene, m-dichlorobenzene, o-dichlorobenzene, p -bromochlorobenzene, 1, 3, 5-trichlorobenzene, 1, 2, 4-trichloro benzene, p-di bromobenzene, 1, 2, 3-trichloro benzene and bromododecane as t welve halogenated hydrocarbon organic petroleum tracer. The separation was performed on a Kromasil HP-5 column (phenyl met hyl siloxane, 60 m X 320 µm X O. 25 µm). The carrier gas (N2 ) was at a flow rate of 1. 0 mL/min. Quantitative analysis of halogenated hydrocarbon organic petroleum tracer was carried out by electron ionizatio n (El) source and selective ion monitoring (SIM) mode, the sample inject volume was 2 µL, the ion source temperature was 260 °C and the auxiliary heating temperature was 280 °C. The results showed that twelve halogenated hydrocarbon organic petroleum tracer had good linear relationship in the range of 10-10 000 µg/L, the limit detection was 10-4 µg/L, and the standard addition recovery rate was less than 3% . This method has good precision, sensitive, simple and rapid pretreatment, which is suit able for determine the content of petroleum tracer, also can provide a technical way for petroleum tracer detection in the process of petroleum development. [ABSTRACT FROM AUTHOR]

Highlights • We evaluated thirteen hydrophobic ionic liquids (ILs) for destruction of three halogenated hydrocarbons. • We evaluated the effect of contact time on the destruction efficiency of ILs. • We also assessed the effect of potassium superoxide (KO 2) dose on the destruction efficiency. • We interpolated physico-chemical properties of halogenated hydrocarbons regarding the destruction efficiency. Abstract Ionic liquids (ILs) have been investigated as a media for destruction of halogenated hydrocarbons (HHCs) because of their affinity to solubilize pollutants, hydrophobicity, ability to generate and maintain free radicals, and long term stability with superoxide ion radical (O 2 −). Three HHCs (CCl₄, CHCl 3 , and CHBr 3) were successfully destructed by O 2 − in 13 hydrophobic ILs, including two piperidinium (PIP-ILs), four pyrrolidinium (PYRR-ILs), and seven ammonium-cation based ILs (AM-ILs). The effects of contact time and potassium superoxide (KO 2) dose on the destruction efficiency were evaluated using analysis of variance. 1-propyl -1- methylpiperidinium, 1-octyl-1-Methylpyrrolidinium, and octyltriethylammonium paired with bis (trifluoromethylsulfonyl) imide were found to be the best performers amongst PIP-ILs, PYRR-ILs, and AM-ILs. CHCl 3 , CCl₄ and CHBr 3 consumed about 8, 11, and 14 KO 2 /HHC mole ratio to achieve 95% of optimum destruction efficiency. High viscosity was identified as the main drawback of [N8881][Tf 2 N] and [N4441][Tf 2 N]. Destruction was moderately fast and steady state efficiency was achieved within 30 min. The strong correlations between empirical polarity E T N of HHCs, work as co-solvents, and destruction efficiencies were obtained with R 2 values higher than 0.99. The study presents a useful insight to use ILs as alternative solvents for treatment of hazardous wastes. [ABSTRACT FROM AUTHOR]

The Montreal Protocol’s Multilateral Fund is often hailed as a key component of strategies aimed at reducing the amount of ozone-depleting substances in the less-developed countries. Yet, while there are studies that exemplify how the fund has been implemented as well as the strategies that individual countries adopt, there is still a lack of academic literature about the steps taken and implemented to devise successful alternative production strategies. In this case study, we analyze Jordon’s current strategy to reduce ozone-depleting Halon 1211 and 1301, two fully halogenated hydrocarbons that are extensively used in Jordan for their exceptional fire-extinguishing characteristics. In response to the Montreal Protocol, an international treaty to phase out halon use, Jordan adopted a halon management program to manage the use of halons, build strategic reserves for “essential uses,” and limit the amount of these substances that are released into the atmosphere. This study presents the actual inventory data of halons in Jordan in addition to the challenges and obstacles in the halon bank management system in Jordan. Moreover, this research covers the prospects of Jordan halons banking to achieve the goal of meeting Jordan’s halons demand for essential uses up to the year 2030. To this end as well as to fulfill Jordan’s commitment to the Montreal Protocol, the research recommends finding the balance between effectively enforcing regulations against the use of ozone-depleting substances while being able to meet halons demand for the essential uses until alternatives are comparably affordable and available on the national market. The research recommends that regulations should be supported with effective governance measures to minimize the occurrences of ozone-depleting substances escaping into the atmosphere as well as to meet halons demand. [ABSTRACT FROM AUTHOR]

Halogenated hydrocarbons (HHCs) are members of priority water pollutants due to their adverse health and environmental impacts and their removal from water is of paramount importance. In this research, six different types of hydrophobic ionic liquids (ILs) were evaluated for the extraction of three HHCs from water, namely carbon tetrachloride (CCl 4 ), chloroform (CHCl 3 ), and bromoform (CHBr 3 ). The ILs were selected based on their: (i) affinity to solubilize contaminants of concern, (ii) moderate viscosity, (iii) hydrophobicity, and (iv) stability in the presence of the superoxide ion that will be used for the destruction of HHCs. The selected ILs successfully removed HHCs from water with extraction efficiencies ranging from 83% to 99%. It was found that octyltriethyl-ammonium and -pyrrolidinium cation paired with bis (trifluoromethylsulfonyl) imide [Tf 2 N] anion exhibit high performance for extracting CCl 4 , CHCl 3 , and CHBr 3 . The effect of process parameters, including contact time, temperature, pH, hydrogen bond donor ( α ), hydrogen bond acceptor ( β ), dipolarity/polarizability ( π ∗ ), and octanol/water partition coefficient ( K ow ) on the extraction efficiency were also investigated. It was also found that optimal extraction efficiency was achieved within 5 min contact time. The study found selected ILs can be effectively used for water and wastewater treatment. The extraction of HHCs through ILs can also be used as a potential analytical approach for the identification of HHCs in water by chromatography technique. [ABSTRACT FROM AUTHOR]

Emergency exposure guidance levels have been developed for many halogenated hydrocarbons. These can be employed in the event of accidental releases or terrorist actions. However, for a chemical release involving a substance without existing guidance levels, there is a need to be able to develop one rapidly. Two data sources are available, the Acute Exposure Guideline Levels (AEGL) and Emergency Response Guideline Levels (ERPG). The subset of halogenated hydrocarbons and related substances included in these data sources represent 30 chemicals and 41 risk assessments. The ratios for serious toxicity/annoyance level and for potential lethality/serious toxicity were calculated. On reviewing the results, the geometric means provided the best basis for extrapolation. When the geometric means of the ratios of ERPG-3/ERPG-2 and AEGL-3/AEGL-2 were calculated their combined mean was 4.40. The geometric standard deviation for the combined data set was 2.00 suggesting the data were homogeneous. Likewise, calculation of the geometric means for ERPG-2/1 and AEGL-2/1 the combined ratio was 3.93. The geometric standard deviation for the combined set was 1.46, again suggesting homogeneity of the data. The review described in this paper confirmed that the time default “n” values of 3 and 1 (ten Berge et al., 1986) are appropriate for extrapolation to shorter and longer exposure times, respectively. [ABSTRACT FROM AUTHOR]

Between 1975 and 2006, drilling rigs and utility trucks were assembled at the site. The geology and hydrogeology at the site was defined based on subsurface data, soil descriptions and geophysical logs from 38 wells and 3 coreholes. The results of the water samples collected from shallow and deep wells indicate that many wells have concentrations of halogenated hydrocarbons above regulatory standards and that contaminant migration has occurred vertically, laterally, and along strike. Impacted groundwater covers most of the property and has migrated to 68.5 m below land surface. Two pilot studies (one bench-scale and one on-site) have been completed to evaluate the application of technologies in addressing contamination of shallow and deep groundwater at the site underlain by the Conasauga Formation. [ABSTRACT FROM AUTHOR]

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Measurement assurance in the identification of ozone-depleting substances is considered. It is indicated thatozone-depleting halogenated hydrocarbons must be monitored, and portable devices for detecting counterfeits in customs border control are needed. [ABSTRACT FROM AUTHOR]

A quantitative structure-infinite dilution activity relationship was developed to predict the infinite dilution activity coefficients of halogenated hydrocarbons, γ, in water at 298.15 K. A set of 1,497 zero-to three-dimentional descriptors were used for each molecule in the data set. Classification and regression tree (CART) were successfully used as a descriptor selection method. Three descriptors were selected and used as inputs for the adaptive neuro-fuzzy inference system (ANFIS). The root mean square errors for both calibration and prediction sets are 0.48. The results were compared with those obtained from other models. The results showed that CART-ANFIS can be used as a powerful model for prediction of the infinite dilution activity coefficients of halogenated hydrocarbons. [ABSTRACT FROM AUTHOR]

The distribution of electronic charge in a molecule plays a major role in determining the molecule's physical, chemical, and biological properties. For studies of charge distributions, halogenated hydrocarbons are especially informative prototype systems, because the overall charge distributions depend strongly on both the identities and relative positions of the halogen substituents. In this report, we examine how the placement and identities of the halogen substituents affect the natural population analysis, atoms in molecules, and Gasteiger partial atomic charge distributions in representative saturated (methanes and ethanes), unsaturated (ethylenes), and aromatic (benzenes) halogenated hydrocarbons, using density functional calculations. The results are interpreted in terms of the electronegativities and the charge capacities of the halogens. The relationships of these charge distributions to the electrostatic potential maps of the compounds are also explored. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2012 [ABSTRACT FROM AUTHOR]

Abstract: We measured partial pressures of CH2Cl2 (dichloromethane) and CCl3F (CFC-11) in air and surface seawater of the Indian and Southern Oceans from November 2009 to January 2010. The excess CH2Cl2 saturation anomaly (ΔSACH2Cl2 >0) in surface seawater between 10°S and 40°S, which is the corrected value of saturation anomaly after subtracting the effects of summertime sea-surface temperature increase and of summertime decrease of atmospheric CH2Cl2 level, provides evidence for in-situ production of CH2Cl2. Depth profiles from the South Indian Ocean at 5°S, 20°S and 30°S showed concentration maxima of dihalomethanes (CH2I2, CH2ClI and CH2Cl2) and chlorophyll-a in the subsurface layer (20–150m). Our data suggest that phytoplankton production of dihalomethanes leads to concentration maxima in the subsurface layer and ΔSACH2Cl2 >0 in surface seawater between 10°S and 40°S. The average oceanic emission of CH2Cl2 derived from the region between 10°S and 40°S in the South Indian Ocean was calculated to be 0.29–0.43μg m−2 d−1. [Copyright &y& Elsevier]

n enzyme-based biosensor was developed by co-immobilization of purified enzyme haloalkane dehalogenase (EC 3.8.1.5) and a fluorescence pH indicator on the tip of an optical fiber. Haloalkane dehalogenase catalyzes hydrolytic dehalogenation of halogenated aliphatic hydrocarbons, which is accompanied by a pH change influencing the fluorescence of the indicator. The pH sensitivity of several fluorescent dyes was evaluated. The selected indicator 5(6)-carboxyfluorescein was conjugated with bovine serum albumin and its reaction was tested under different immobilization conditions. The biosensor was prepared by cross-linking of the conjugate in tandem with haloalkane dehalogenase using glutaraldehyde vapor. The biosensor, stored for 24 h in 50 mM phosphate buffer (pH 7.5) prior to measurement, was used after 15 min of equilibration, the halogenated compound was added, and the response was monitored for 30 min. Calibration of the biosensor with 1,2-dibromoethane and 3-chloro-2-(chloromethyl)-1-propene showed an excellent linear dependence, with detection limits of 0.133 and 0.014 mM, respectively. This biosensor provides a new tool for continuous in situ monitoring of halogenated environmental pollutants. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Abstract: Biogenic trace gases, especially halomethanes, which are important with respect to atmospheric chemistry, are released from the ocean and carry halogens to the troposphere and stratosphere. The concentrations of 10 halocarbons and isoprene in seawater were measured during the spring of 2007 in the western North Pacific Ocean (37–43° N, 143–146° E). Sea–air fluxes of CH3Cl, CH3Br, CH2ClI, and CH2I2 were also estimated based upon the atmospheric as well as oceanic measurement of these species. Temperature–salinity scatter diagram analyses divided the sampling stations into the Oyashio region, Tsugaru warm current region, and Kuroshio region. Mean (range) concentrations of the gases in the water columns (5–100m) were 114 (56–150) pmolL−1 CH3Cl, 6.9 (4.1–19.4) pmolL−1 CH3Br, 1.7 (0.7–2.9) pmolL−1 CH3I, 1.9 (0.9–4.1) pmolL−1 CH2BrCl, 4.8 (3.2–8.1) pmolL−1 CH2Br2, 1.0 (0.6–1.8) pmolL−1 CHBrCl2, 1.2 (0.7–2.0) pmolL−1 CHBr2Cl, 10.8 (4.7–24.5) pmolL−1 CHBr3, 1.7 (0.7–5.4) pmolL−1 CH2ClI, 3.0 (<0.1–22.2) pmolL−1 CH2I2, and 19.7 (3.8–68.2) pmolL−1 isoprene. The maximum concentration of isoprene was observed in the Oyashio region, where concentrations of chlorophyll a (maximum: 2.94µgL−1) were highest in the present study. However, the peaks of CH3Br, CH2ClI, and CH2I2 were observed in the Tsugaru warm current region, where concentrations of chlorophyll a were not as high (maximum: 0.65µgL−1). The results of chlorophyll a size fractionation showed a high occurrence of halomethanes in the stations dominated by pico-sized phytoplankton. These results indicate the importance of picoplankton as a possible source of halocarbon production. Chlorophyll b and prasinoxanthin had a statistically significant positive correlation with CH2I2 (r 2 =0.69 and r 2 =0.71, respectively) and with CH2ClI (r 2 =0.87 and r 2 =0.77, respectively). These results suggest that some species of prasinophytes might contribute to CH2I2 and CH2ClI production. For other compounds, there was no peak in the vertical profile in seawater. In the depth profiles, the peak of CH2ClI was observed above the peak of CH2I2; these profiles suggest that a photochemical reaction could yield CH2ClI from CH2I2 in seawater. The mean mixing ratio and range of CH3Cl, CH3Br, and CH2ClI in the air were measured as 548 (524–609), 12.1 (8.6–19.0), and 0.27 (0.03–0.90) pptv, respectively. CH2I2 was not detected in the atmosphere (<1pptv). The saturation anomaly of CH3Br was positive at all stations (the sea surface temperature varied from 1.7°C to 19°C). The highest mixing ratio of CH2ClI in air was also observed near the station at which the highest concentration of CH2ClI was observed in seawater; the sea-to-air fluxes of CH2ClI and CH2I2 were 3.8 and 1.6nmolm−2 day−1, respectively. These results suggest that the production of CH2ClI and CH2I2 in seawater is an important source of organic iodine compounds in the remote atmosphere. [Copyright &y& Elsevier]

Abstract: We determined the distributions and fluxes of methyl chloride and methyl bromide in the East China Sea (ECS) and the Southern Yellow Sea (SYS) in November 2007. Methyl chloride and methyl bromide concentrations in the surface waters ranged from 47.1 to 163pmolL− 1 and from 0.70 to 9.82pmolL−1, with average values of 87.6 and 2.97pmolL−1, respectively. The distributions of the two methyl halides were clearly influenced by the Yangtze (Changjiang) River effluent and Kuroshio water, with high concentrations appearing in the coastal zone and low values occurring in the open waters. A positive linear correlation was observed between methyl chloride and methyl bromide concentration anomalies in the surface waters, suggesting that they may share some origins in this coastal area. However, no correlation was found between the two methyl halide concentration anomalies and chlorophyll a in the surface waters. The vertical profiles of the two methyl halides were characterized by the maxima in the upper mixed layer. Both gases were generally supersaturated in the surface seawater, with mean sea-to-air fluxes of methyl chloride and methyl bromide of 391 and 20.0nmolm− 2 d−1, respectively. [Copyright &y& Elsevier]

Abstract: Measurements of bromoform (CHBr3), diiodomethane (CH2I2), chloroiodomethane (CH2ICl) and bromoiodomethane (CH2IBr) were made in the water column (5–100 m depth) of the Southern Ocean within 0–40 km of the Antarctic sea ice during the ANTXX1/2 transect of the German R/V Polarstern, at five locations between 70–72°S and 9–11°W in the Antarctic spring/summer of 2003–2004. Some of the profiles exhibited a very pronounced layer of surface sea-ice meltwater, as evidenced by salinity minima and temperature maxima, along with surface maxima in concentrations of CHBr3, CH2I2, CH2ICl and CH2IBr. These results are consistent with in situ surface halocarbon production by ice algae liberated from the sea ice, although production within the sea ice followed by transport cannot be entirely ruled out. Additional sub-surface maxima in halocarbons occurred between 20 and 80 m. At a station further from shore and not affected by surface sea-ice meltwater, surface concentrations of CH2I2 were decreased whereas CH2ICl concentrations were increased compared to the stations influenced by meltwater, consistent with photochemical conversion of CH2I2 to CH2ICl, perhaps during upward mixing from a layer at ∼70 m enhanced in iodocarbons. Mean surface (5–10 m) water concentrations of halocarbons in these coastal Antarctic waters were 57 pmol l−1 CHBr3 (range 44–78 pmol l−1), 4.2 pmol l−1 CH2I2 (range 1.7–8.2 pmol l−1), 0.8 pmol l−1 CH2IBr (range 0.2–1.4 pmol l−1), and 0.7 pmol l−1 CH2ICl (range 0.2–2.4 pmol l−1). Concurrent measurements in air suggested a sea-air flux of bromoform near the Antarctic coast of between 1 and 100 (mean 32.3, median 10.4) nmol m−2 day−1 and saturation anomalies of 557–1082% (mean 783%, median 733%), similar in magnitude to global shelf values. In surface samples affected by meltwater, CH2I2 fluxes ranged from 0.02 to 6.1 nmol m−2 day−1, with mean and median values of 1.9 and 1.1 nmol m−2 day−1, respectively. [Copyright &y& Elsevier]

Standard enthalpies of formation of halogenated hydrocarbons were calculated from models developed for the computer program SPARC. SPARC uses computational algorithms based on chemical structure theory to calculate molecular properties. Molecular structures are broken into simple functional units (reactophores) with intrinsic properties. Each reactophore is analyzed and the effects of appended molecular structures are quantified through perturbation theory. The halohydrocarbons modeled include multi-branched chains, simple conjugated rings, and aromatic compounds. SPARC calculates an RMS deviation of 5.18 kJ mol-1 for these 202 compounds. [ABSTRACT FROM AUTHOR]

Metal fluorides are more stable than metals and metal oxides; therefore, no oxides can be applied as catalyst supports for the reactions in which hydrogen fluoride is involved. The authors observed that metal phosphates are not reactive to HF at higher reaction temperatures such as 973 K. Hence, the decomposition of CClF2CClF2 was studied over Pt-supported SiO2, Al2O3, and AlPO4-based catalysts. Hydrodehalogenation proceeded and CHF2CClF2 and C2H6 were formed as major products, small amounts of CHF2CHF2, CH2FCClF2, CH2FCF3, and CH4 were also formed. Pt/SiO2 was the most active; however, SiO2 reacted with HF and the SiF4 formed sublimated. Following these, Al2O3 was the most active; however, it reacted with HF to form AlF3 and was deactivated. Similar hydrodehalogenation proceeded over Pt/AlPO4 and Pt/(CePO4一AlPO4). The crystal structure of these catalysts did not change during the catalytic reaction, although the reduction of specific surface areas (SSA) was observed. Therefore, AlPO4 and Ce containing AlPO4 are suitable as catalyst supports in reactions in which HF is involved. XPS showed that the electronic effects of AlPO4 lie between that of SiO2 and Al2O3. A good linear relationship is found to exist between the initial reaction rates per unit surface area of Pt metal supported on the supports and the binding energy of supported Pt. This suggests that the more cationic the Pt, the more easily it could abstract Cl− from CClF2CClF2. [Copyright &y& Elsevier]

Two small-size plasmas used as detectors of halogenated hydrocarbons and suitable for miniaturized instrumentation are discussed. A reduced pressure dielectric barrier discharge was integrated in a diode laser atomic absorption spectrometer and the already reported chlorine detection limits of 5 ppm (v/v) can be improved with one order of magnitude by spatially resolved measurements. A microstructured electrode discharge at atmospheric pressure was coupled with a miniaturized E´chelle spectrometer and detection limits were found to be 20 ppb for chlorine as well as for fluorine. [Copyright &y& Elsevier]

Toxicological and genotoxicological investigation of complex mixtures is one of the main focus of the recent research in toxicology. Testing complex mixtures present a formidable scientific problem since most recently available toxicological data has been obtained from single substance studies and is not simply transferable to mixtures of chemicals. Although there are no special strategies and standard protocols available for determining toxic and genotoxic effects of complex mixtures, the fundamental concepts of evaluation are the same as those for single substances .The focus of interest of the submitted paper is the genotoxicological characterisation of a complex mixture of mostly perhalogenated hydrocarbons which is generated as a waste product from the plasma etching process in the semiconductor industry. By use of several in vitro test systems (comet assay and micronucleus test), the clastogenic potency of the mixture was tested in various human cell types (lymphocytes and normal bronchial epithelial cells) and in rat hepatocytes. Results demonstrated that the complex perhalogenated hydrocarbons mixture causes DNA single-strand breaks and micronuclei formation, and direct concentration-to-effect correlations were proved in all experiments. The presence of an external metabolising system (S9 mix from rat hepatocytes) in human cell culture systems did not cause any change of the observed effects when compared to experiments performed in the absence of the S9 mix. Therefore, we conclude that the mixture acts as direct genotoxicant and that there is no detoxification by the external enzyme system.Further, convincing and reproducible results of the in vitro comet assay and the micronucleus assay in primary human cell cultures indicated these tests may be utilized for the genotoxicological analyses of complex mixtures with concern to human health hazard. [Copyright &y& Elsevier]

Chloronitrobenzenes are important chemical intermediates in the manufacture of industrial, agricultural and pharmaceutical agents. Toxicity induced by the various chloronitrobenzene isomers in vivo includes hematotoxicity, immunotoxicity, hepatotoxicity and nephrotoxicity. The purpose of the study was to determine the direct nephrotoxic effects of nitrobenzene and ten chlorinated nitrobenzene derivatives using renal cortical slices as the in vitro model. Renal cortical slices were prepared from kidneys of untreated, male Fischer 344 rats and incubated with nitrobenzene (1.0–5.0 mM), a chloronitrobenzene (0.5–5.0 mM) or vehicle for 2 h. At the end of the 2 h incubation, tissue gluconeogenesis capacity (pyruvate-stimulated gluconeogenesis) and lactate dehydrogenase (LDH) release were determined as measures of cellular function and cytotoxicity. Based on decreased pyruvate-stimulated gluconeogenesis and increased LDH release, the order of decreasing nephrotoxic potential was trichloronitrobenzenes>dichloronitrobenzenes>monochloronitrobenzenes>nitrobenzene. Among the mono- and dichloronitrobenzenes, 1-chloro-3-nitrobenzene and 3,4-dichloronitrobenzene were the most potent nephrotoxicants, while the two trichloronitrobenzenes tested exhibited similar nephrotoxic potentials. These results demonstrate that chloronitrobenzenes are directly nephrotoxic in vitro and that increasing the number of chloro groups increases the nephrotoxic potential of the resulting chloronitrobenzene derivative. [Copyright &y& Elsevier]

Male and female rats were exposed by inhalation (whole body) to HCC-230fa (1,1,1,3,3,3-hexachloropropane) for 6 h/day, 5 days/week over a 15-week period. Concentrations of 0, 0.50, 2.5, and 25 ppm were studied. A total of eight groups/sex were exposed. Four groups of male and four groups of female rats were used to measure clinical signs and growth, clinical pathology, and tissue pathology. The remaining four groups of male rats were used for immunotoxicological and sperm assessment evaluations, and the remaining four groups of female rats were used for immunotoxicological evaluation. Following the exposure period, surviving male rats were kept for a 1- or 3-month recovery period. Male and female rats exposed to 25 ppm had lower mean body weights, mean body weight gains, and food consumption during the exposure period. Male and female rats exposed to 25 ppm and sacrificed immediately after the exposure period had minimally decreased total leukocyte and lymphocyte counts. These changes were considered to be marginally adverse. Pathologic examination revealed hepatocellular hypertrophy in 0-day recovery males and an increased incidence and/or severity in chronic progressive nephropathy in 0-day, 1-month recovery, and 3-month recovery males at 25 ppm. No other pathological changes, including the testis, epididymis, and other accessory sex organs, were noted in rats during the study. Evaluation of sperm parameters at the end of the exposure period showed statistically significant decreases in epididymal sperm number per cauda epididymis, percent motile sperm, and percent normal sperm morphology at 25 ppm. The biological significance of the slight changes observed in the sperm parameters in the absence of histopathological changes is unclear. After a 1-month recovery period, no biologically significant differences in sperm parameters were noted at 25 ppm compared with controls. Exposure to HCC-230fa did not significantly alter the primary humoral immune response to sheep red blood cell (SRBC). Under the conditions of this study, the no-observed-adverse-effect level (NOAEL) was considered to be 2.5 ppm. [ABSTRACT FROM PUBLISHER]

Human exposure guidelines for halogenated hydrocarbons (halons) and halon replacement chemicals have been established using dose-response data obtained from canine cardiac sensitization studies. In order to provide a tool for decision makers and regulators tasked with setting guidelines for egress from exposure to halon replacement chemicals, a quantitative approach, using a physiologically based pharmacokinetic model, was established that allowed exposures to be assessed in terms of the chemical concentrations in blood during the exposure. This model, which includes a respiratory tract compartment containing a dead-space region, a pulmonary exchange area, and a breath-by-breath description of respiratory tract uptake, allows successful simulation of exhaled breath concentrations of humans during the first minute of exposure to the anesthetics halothane, isoflurane, and desflurane. In the current study, the human model was modified with canine parameters and validated with data obtained from dog studies with halothane, isoflurane, desflurane, and CFC-11. With consideration of appropriate values for ventilation and cardiac output, the model successfully simulated data collected under a variety of exposure scenarios. The canine model can be used for simulating blood concentrations associated with the potential for cardiac sensitization. These target blood concentrations can then be used with the human model for establishing safe human exposure duration. Development of the canine model stresses the need for appropriate data collection for model validation. [ABSTRACT FROM PUBLISHER]