Replacements For Chlorofluorocarbons Research Articles

Levels and distribution profiles of Per- and Polyfluoroalkyl Substances (PFAS) in a high Arctic Svalbard ice core

Per- and polyfluoroalkyl substances (PFAS) are a group of persistent organic contaminants of which some are toxic and bioaccumulative. Several PFAS can be formed from the atmospheric degradation of precursors such as fluorotelomer alcohols (FTOHs) as well as hydrochlorofluorocarbons (HFCs) and other ozone-depleting chlorofluorocarbon (CFC) replacement compounds. Svalbard ice cores have been shown to provide a valuable record of long-range atmospheric transport of contaminants to the Arctic. This study uses a 12.3 m ice core from the remote Lomonosovfonna ice cap on Svalbard to understand the atmospheric deposition of PFAS in the Arctic. A total of 45 PFAS were targeted, of which 26 were detected, using supercritical fluid chromatography (SFC) tandem mass spectrometry (MS/MS) and ultra-performance liquid chromatography (UPLC) MS/MS. C2 to C11 perfluoroalkyl carboxylic acids (PFCAs) were detected continuously in the ice core and their fluxes ranged from 2.5 to 8200 ng m−2 yr−1 (9.51–16,500 pg L−1). Trifluoroacetic acid (TFA) represented 71 % of the total mass of C2 – C11 PFCAs in the ice core and had increasing temporal trends in deposition. The distribution profile of PFCAs suggested that FTOHs were likely the atmospheric precursor to C8 – C11 PFCAs, whereas C2 – C6 PFCAs had alternative sources, such as HFCs and other CFC replacement compounds. Perfluorooctanesulfonic acid (PFOS) was also widely detected in 82 % of ice core subsections, and its isomer profile (81 % linear) indicated an electrochemical fluorination manufacturing source. Comparisons of PFAS concentrations with a marine aerosol proxy showed that marine aerosols were insignificant for the deposition of PFAS on Lomonosovfonna. Comparisons with a melt proxy showed that TFA and PFOS were mobile during meltwater percolation. This indicates that seasonal snowmelt and runoff from post-industrial accumulation on glaciers could be a significant seasonal source of PFAS to ecosystems in Arctic fjords.

Increasing Accumulation of Perfluorocarboxylate Contaminants Revealed in an Antarctic Firn Core (1958-2017).

Perfluoroalkyl acids (PFAAs) are synthetic chemicals with a variety of industrial and consumer applications that are now widely distributed in the global environment. Here, we report the measurement of six perfluorocarboxylates (PFCA, C4–C9) in a firn (granular compressed snow) core collected from a non-coastal, high-altitude site in Dronning Maud Land in Eastern Antarctica. Snow accumulation of the extracted core dated from 1958 to 2017, a period coinciding with the advent, use, and geographical shift in the global industrial production of poly/perfluoroalkylated substances, including PFAA. We observed increasing PFCA accumulation in snow over this time period, with chemical fluxes peaking in 2009–2013 for perfluorooctanoate (PFOA, C8) and nonanoate (PFNA, C9) with little evidence of a decline in these chemicals despite supposed recent global curtailments in their production. In contrast, the levels of perfluorobutanoate (PFBA, C4) increased markedly since 2000, with the highest fluxes in the uppermost snow layers. These findings are consistent with those previously made in the Arctic and can be attributed to chlorofluorocarbon replacements (e.g., hydrofluoroethers) as an inadvertent consequence of global regulation.

Ice Core Record of Persistent Short‐Chain Fluorinated Alkyl Acids: Evidence of the Impact From Global Environmental Regulations

AbstractShort chain perfluoroalkylcarboxylic acids (scPFCAs, CxF2x+1COOH, x ≤ 3) are persistent compounds formed from atmospheric oxidation of fluorotelomer compounds and chlorofluorocarbon (CFC) replacements introduced as a result of the Montreal Protocol. Understanding sources and impacts of scPFCAs has been limited by observational data. We report multidecadal depositional fluxes for trifluoroacetic acid (TFA), perfluoropropionic acid (PFPrA), and perfluorobutanoic acid (PFBA) from two Arctic ice cores. Fluxes of all three scPFCAs increase starting around 1990. Through comparison with chemical transport models and assessment of temporal trends, we observe the importance of CFC replacements in the increased deposition of TFA. Fluorotelomer degradation may contribute to the deposition of PFBA but is insignificant for TFA and PFPrA. Deposition of TFA is expected to increase as new CFC replacement compounds are phased in. This work demonstrates the increased environmental burden of persistent and potentially toxic scPFCAs as a result of global regulation.

CFC replacements are polluting the Arctic

Most countries began phasing out ozone-depleting chlorofluorocarbons (CFCs) in the early 1990s under the Montreal Protocol on Substances That Deplete the Ozone Layer. Replacing these refrigerants and propellants did the trick—the ozone layer recovered. However, a new analysis of Arctic ice cores points to an unintended consequence of this regulation. Over the years, the compounds that replaced CFCs have been transported and transformed in the atmosphere, getting deposited far from their sources. As a result, short-chain fluorinated alkyl acids, which are highly mobile persistent organic pollutants, are accumulating in the Arctic, and likely all around the Northern Hemisphere (Geophys. Res. Lett. 2020, DOI: 10.1029/2020GL087535). York University atmospheric chemist Cora Young has previously found long-chain per- and polyfluoroalkyl substances (PFAS) in Arctic ice. In her new research, she focused on smaller compounds in this class, which haven’t been studied as much. Researchers had hypothesized that levels of these short-chain compounds were

Decoupling the Effects of Transport and Chemical Loss on Tropospheric Composition: A Model Study of Path‐Dependent Lifetimes

AbstractThe distribution of most trace species within the troposphere depends on a complex interplay between chemistry and transport. Holzer and Waugh (2015) introduced the concept of a path‐dependent lifetime τc(r), that parameterizes the integrated chemical loss during transport from the source to a given location r. Here we examine whether this parameterization provides a new approach for decoupling transport and chemistry. We present calculations of path‐dependent lifetimes for a suite of chlorofluorocarbon replacement gases in a simple 12‐box model and show that for trace species with global lifetimes from 0.5 years to 50 years τc provides an accurate representation of the integrated chemical loss during transport. The value of τc is shown to be sensitive to tropical hydroxyl radical (OH) concentrations, with much weaker sensitivity to extratropical OH or transport. Furthermore, fractional changes in Southern Hemisphere extratropical τc are similar to the corresponding fractional changes in tropical OH; that is, a 10% increase in tropical OH results in a 10% decrease in τc. This suggests that observation‐based estimates of τc may be used to constrain tropical OH concentrations provided that τc can be determined with sufficient precision.

Manufacture of hydrofluorocarbons and hydrofluoroolefins as the CFCs-alternatives: from fundamental of catalytic reaction to commercialization

Fluorohydrocarbons including hydrofluorocarbons and hydrofluoroolefins are environment-friendly replacements for chlorofluorocarbons, one kind of ozone-depleting substances. The development and application of catalytic synthesis technologies for fluorohydrocarbon have become an important approach to protect ozone layer, to response climatic change and to fulfill the international environmental conventions. In this paper, the progress on catalytic synthesis technologies for fluorohydrocarbon was summarized on the basis of thirty year’s research of Xi’an Modern Chemistry Research Institute. As the core of synthesis for fluorohydrocarbon, the recent progress of gas-phase catalytic fluorination is reviewed from fundamental research to engineering application, such as reaction mechanism, catalyst preparation, and integration of synthesis technologies. The relative technologies for commercialization and the future technological progress in this field are also briefly analyzed and discussed.

Experimental estimation of the atmospheric lifetimes of CF2HI, CF3CH2I, CF3(CH2)2I and CF3(CH2)3I with removal via the sunlight photolysis and the reactions with NO3

Hydroiodofluorocarbons (HIFCs) have recently attracted attention as new candidates for replacements for chlorofluorocarbons and bromofluorocarbons. Thus, it is very important for the practical and industrial use of HIFCs to know the atmospheric removal processes of HIFCs emitted into the atmosphere. In this study, the absorption spectra of difluoroiodomethane (CF2HI), 1,1,1-trifluoro-2-iodoethane (CF3CH2I), 1,1,1-trifluoro-3-iodopropane [CF3(CH2)2I] and 1,1,1-trifluoro-4-iodobutane [CF3(CH2)3I] were experimentally determined to estimate the lifetimes of the removals from the atmosphere by the sunlight photolysis. The absorption maxima for these HIFCs are at ~262 nm and their peak absorption cross sections range from 6.8 × 10−19 to 8.5 × 10−19 cm2 molecule−1. These results suggest that the lifetimes of the studied HIFCs by solar photolysis are ranged from 7.2 to 14 h. The reactions of NO3 with the four HIFCs were also investigated using time-resolved cavity ring-down spectroscopy. The rate constant values of (4.3 ± 1.1), (5.5 ± 2.7), (6.6 ± 3.7), (9.5 ± 3.1) × 10−14 cm3 molecule−1 s−1 have been determined for the reactions of NO3 with CF2HI, CF3CH2I, CF3(CH2)2I and CF3(CH2)3I at 298 K and 100 Torr of total pressure (the errors designate 2σ statistical uncertainty). The determined values of the rate constants suggest that the lifetimes of the studied four HIFCs with respect to reactions with NO3 range from 12 to 26 h.

Identification of a N 7-guanine adduct of 1-bromopropane in calf thymus DNA by mass spectrometry

As a replacement for chlorofluorocarbons that cause ozone depletion, 1-bromopropane has been widely used in work place. In the present study, the formation of N 7-guanine adduct in DNA by 1-bromopropane was evaluated in vitro to elucidate the possible mechanism of its toxic action. N 7-Propyl guanine was chemically synthesized and structurally characterized by NMR, UV, HPLC, and liquid chromatographyelectrospray ionization mass spectrometry (LC- ESI MS) for using as a reference standard. An incubation of 2ʹ-deoxyguanosine with 1-bromopropane produced N 7-propyl adduct, which was identified by UV, HPLC and ESI-MS. In addition, N7-guanine adduct was also identified from the incorporation of calf thymus DNA with 1-bromopropane at the physiological condition by LC-ESI MS. Furthermore, the production of adduct was proportional to the amounts of 1-bromopropane used. These results indicated that the molecular mechanism underlying toxic effects of 1-bromopropane would be associated with the adduct formation on DNA at least in part.

The Madrid Statement on Poly- and Perfluoroalkyl Substances (PFASs).

As scientists and other professionals from a variety of disciplines, we are concerned about the production and release into the environment of an increasing number of poly- and perfluoroalkyl substances (PFASs) for the following reasons: PFASs are man-made and found everywhere. PFASs are highly persistent, as they contain perfluorinated chains that only degrade very slowly, if at all, under environmental conditions. It is documented that some polyfluorinated chemicals break down to form perfluorinated ones (D’Eon and Mabury 2007). PFASs are found in the indoor and outdoor environments, wildlife, and human tissue and bodily fluids all over the globe. They are emitted via industrial processes and military and firefighting operations (Darwin 2011; Fire Fighting Foam Coalition 2014), and they migrate out of consumer products into air (Shoeib et al. 2011), household dust (Bjorklund et al. 2009), food (Begley et al. 2008; Tittlemier et al. 2007; Trier et al. 2011), soil (Sepulvado et al. 2011; Strynar et al. 2012), ground and surface water, and make their way into drinking water (Eschauzier et al. 2012; Rahman et al. 2014). In animal studies, some long-chain PFASs have been found to cause liver toxicity, disruption of lipid metabolism and the immune and endocrine systems, adverse neurobehavioral effects, neonatal toxicity and death, and tumors in multiple organ systems (Lau et al. 2007; Post et al. 2012). In the growing body of epidemiological evidence, some of these effects are supported by significant or suggestive associations between specific long-chain PFASs and adverse outcomes, including associations with testicular and kidney cancers (Barry et al. 2013; Benbrahim-Tallaa et al. 2014), liver malfunction (Gallo et al. 2012), hypothyroidism (Lopez-Espinosa et al. 2012), high cholesterol (Fitz-Simon et al. 2013; Nelson et al. 2009), ulcerative colitis (Steenland et al. 2013), lower birth weight and size (Fei et al. 2007), obesity (Halldorsson et al. 2012), decreased immune response to vaccines (Grandjean et al. 2012), and reduced hormone levels and delayed puberty (Lopez-Espinosa et al. 2011). Due to their high persistence, global distribution, bioaccumulation potential, and toxicity, some PFASs have been listed under the Stockholm Convention (United Nations Environment Programme 2009) as persistent organic pollutants (POPs). As documented in the Helsingor Statement (Scheringer et al. 2014), Although some of the long-chain PFASs are being regulated or phased out, the most common replacements are short-chain PFASs with similar structures, or compounds with fluorinated segments joined by ether linkages. While some shorter-chain fluorinated alternatives seem to be less bioaccumulative, they are still as environmentally persistent as long-chain substances or have persistent degradation products. Thus, a switch to short-chain and other fluorinated alternatives may not reduce the amounts of PFASs in the environment. In addition, because some of the shorter-chain PFASs are less effective, larger quantities may be needed to provide the same performance. While many fluorinated alternatives are being marketed, little information is publicly available on their chemical structures, properties, uses, and toxicological profiles. Increasing use of fluorinated alternatives will lead to increasing levels of stable perfluorinated degradation products in the environment, and possibly also in biota and humans. This would increase the risks of adverse effects on human health and the environment. Initial efforts to estimate overall emissions of PFASs into the environment have been limited due to uncertainties related to product formulations, quantities of production, production locations, efficiency of emission controls, and long-term trends in production history (Wang et al. 2014). The technical capacity to destroy PFASs is currently insufficient in many parts of the world. Global action through the Montreal Protocol (United Nations Environment Programme 2012) successfully reduced the use of the highly persistent ozone-depleting chlorofluorocarbons (CFCs), thus allowing for the recovery of the ozone layer. However, many of the organofluorine replacements for CFCs are still of concern due to their high global warming potential. It is essential to learn from such past efforts and take measures at the international level to reduce the use of PFASs in products and prevent their replacement with fluorinated alternatives in order to avoid long-term harm to human health and the environment. For these reasons, we call on the international community to cooperate in limiting the production and use of PFASs and in developing safer nonfluorinated alternatives. We therefore urge scientists, governments, chemical and product manufacturers, purchasing organizations, retailers, and consumers to take the following actions:

Assessment of Efficacy and Safety between Two Formulations of Formoterol Fumarate in Adolescents and Adults with Persistent Asthma

Objective: The mandatory replacement of chlorofluorocarbons (CFCs) in pressurized metered dose inhalers (pMDIs) with non ozone depleting propellants such as hydrofluoroalkanes (HFA 134a) requires clinical testing that ensures the reformulated aerosol with HFA is as effective and well tolerated as the original CFC version. In view of this, a multicentre, randomised, parallel-group, double-blind study was conducted to compare the safety and efficacy of formoterol fumarate delivered by a MDI using the hydrofluoroalkane (HFA) 134a propellant (Cipla Ltd) with the CFC formulation (Foradil CFC pMDI, Novartis, UK) in adolescents and adults. Methods: Patients on a stable dose of inhaled corticosteroids with a scope for improvement based on mean morning peak expiratory flow (PEF) and symptoms were randomised to receive formoterol HFA MDI 24 mg twice daily or formoterol CFC MDI 24 mg twice daily for 12 weeks. The primary efficacy variable was the mean morning PEF and secondary variables included FEV1, symptom scores, use of relief medication and safety assessments. Results: The difference between the treatments in the adjusted mean morning PEF (formoterol HFA–formoterol CFC) was -4.68 L/min (95% CI: -13.45, 4.09). The lower limit of the 95% confidence interval was within the pre-defined limit (20 L/min) set for non-inferiority. The results of the secondary endpoints supported the findings of the primary endpoint. The incidences of adverse events (AEs) were similar for both formulations. Conclusion: The results of this study confirm that formoterol HFA pMDI is as effective as formoterol CFC pMDI in adolescents and adults.

Analysis of diurnal variability of atmospheric halocarbons and CFC replacements to imply emission strength and sources at an urban site of Lukang in central Taiwan

Hourly atmospheric measurements of halocarbons and chlorofluorocarbon (CFC) replacements were conducted at an urban site of Lukang, Changhua, in central Taiwan from May to August, 2013. The temporal distribution of different groups of halocarbons in the Lukang urban atmosphere, including chlorofluorocarbons (CFCs), Chlorodifluoromethane (HCFC-22), Bromochlorodifluoromethane (Halon-1211), and other chlorinated compounds, is presented and discussed. The concentrations (mixing ratios) of HCFC-22, Dichlorodifluoromethane (CFC-12), Halon-1211, Trichlorofluoromethane (CFC-11), Dichloromethane (CH2Cl2), and Trichloroethylene (TCE) were enhanced with respect to the local background levels; the atmospheric mixing ratio of carbon tetrachloride (CCl4) was slightly higher than its local background level; on the other hand, 1,1,2-Trichlorotrifluoroethane (CFC-113) was relatively uniform and not very different from background atmospheric level in non-urban areas. Among these compounds, HCFC-22, Halon-1211 and the halogenated compounds, CH2Cl2 and TCE, used as solvents were strongly enhanced. The average mixing ratio of Halon-1211 was higher than the local background of ∼4.5 ppt by ∼60% although Halon-1211 production had been phased out by 1996.Hourly average mixing ratios of halocarbons (HCFC-22, CFC-12, Halon-1211, CFC-11, CH2Cl2, and TCE) illustrated a distinct diurnal cycle characterized with a pattern of elevated mixing ratio and large mixing ratio variability amplitude at night relative to that in daytime. Although emission sources of these halocarbons were complex, hourly average mixing ratios for most of these high variability halocarbons peaked at ∼5:00 AM when the hourly average wind speed reached the minimum value of the day; by contrast, the hourly average mixing ratio of CO peaked at ∼8:30 AM when the ambient atmospheric wind condition was strongly influenced by sea breezes during the traffic rush hours. This phenomenon revealed that meteorological factors predominated the distribution of halocarbon mixing ratio in the urban atmosphere and the traffic emission of CFC-12 derived from old vehicles manufactured before 1994 was insignificant to the CFC-12 mixing ratio in the urban atmosphere. The meteorological condition of nighttime atmospheric temperature inversion and low wind speed facilitated the accumulation of terrestrial airborne pollutants near the ground; consequently the hourly average mixing ratios at night were higher than those in daytime by up to ∼2% (CFC-11), ∼7% (CFC-12), ∼75% (HCFC-22), ∼72% (Halon-1211), ∼280% (CH2Cl2), and ∼155% (TCE).

Hydroxyl-Radical-Initiated Oxidation Mechanism of Bromopropane

Bromopropane has been considered as a replacement for chlorofluorocarbons used as the active component of industrial cleaning solvents, more specifically for HCFC-141b. The proposed mechanism for the atmospheric oxidation of bromopropane is studied via ab initio methodology. Ab initio molecular orbital methods at the CCSD(T)/6-311++G(2df,2p)//MP2/6-31G(d) level of theory have been used to determine the structure and energetics of the 58 species and transition states involved in the atmospheric oxidation of bromopropane. The calculations show that the major oxidation species is bromoacetone. Other brominated species that result from the oxidation are BrCH 2CH 2C(O)H, BrC(O)CH 2CH 3, and BrC(O)H, potential new bromine reservoir species that result from bromopropane in the atmosphere.

The cooling effect by an adsorption-desorption refrigeration cycle

An experiment has been carried out utilizing the activated carbon granules as an adsorbent indige-nously developed from coconut shell and carbon dioxide gas as an adsorbate in a small experimental chamber, specially designed for this purpose. Adsorption followed by removal of heat of adsorp-tion and subsequent desorption produces refrigera-tion. After a few cycles in the chamber, tempera-tures drop from 304 K to 282.5 K. Therefore, con-tinuous production of refrigeration could be achieved by a suitable mechanism. The paper describes the details of the design and fabrication of the experimental chamber, the experimental proce-dure and discusses the results obtained to assess its feasibility towards development of an alternative eco friendly refrigeration cycle for replacement of chlorofluorocarbons.

The challenge to develop CFC (chlorofluorocarbon) replacements: a problem based learning case study in green chemistry

The value of case studies for teaching both subject specific and transferable skills within chemistry have long been recognised. Coupling this with problem based learning provides a powerful basis for teaching transferable skills within a chemistry context. This problem based learning case study does this via the fascinating story of the industrial challenge to develop CFC (chlorofluorocarbon) replacements on a very short time scale. It provides a vehicle for developing team working, communication, critical thinking, data interpretation and problem solving skills in a ‘real life’ context. It also introduces students to environmental issues and green chemistry plus the role of the chemical industry in developing solutions to these issues. The, often competing, interplay between chemistry, economics and social and political factors encourages (?) students to make links between different areas of the curriculum and to also appreciate that there are not always single ‘correct’ answers to scientific problems. Attention is focussed on the discovery and development of the CFC replacement HFA–134a. The paper concludes with a report on the trialling of, and student feedback for, the case study. [Chem. Educ. Res. Pract., 2006, 7 (4), 280-287]

Pharmacokinetics of Beclomethasone Dipropionate in an Hydrofluoroalkane-134a Propellant System in Japanese Children with Bronchial Asthma

Hydrofluoroalkane-134a (HFA) has been shown to be a safe replacement for chlorofluorocarbons (CFCs) as a pharmaceutical propellant, with the advantage that it has no ozone-depleting potential. This is the first report of the pharmacokinetics of beclomethasone dipropionate (BDP) delivered from a pressurized solution formulation using an HFA propellant system (HFA-BDP) in Japanese children with bronchial asthma. Plasma concentrations of beclomethasone 17-monopropionate (17-BMP),a major metabolite of BDP, following an inhaled dose of HFA-BDP (200 microg as four inhalations from 50 microg/actuation) in five Japanese children with bronchial asthma were quantified and analyzed by a non-compartmental analysis to obtain pharmacokinetic parameters. The area under the concentration-time curve from time zero to the last quantifiable time (AUC(0-t)) was 1659 +/- 850 pg x h/mL (arithmetic mean +/- standard deviation (SD)), the maximum concentration observed (C(max)) was 825 +/- 453 pg/mL and the apparent elimination half-life (t(1/2)) was 2.1 +/- 0.7 hours. The time to reach Cmax Tmax was 0.5 hours in all patients. No special relationship was observed between these parameters and age or body weight. These parameters were compared with the previously reported parameters of American children with bronchial asthma. The Japanese/American ratio of the geometric means of each parameter was 1.36 for AUC(0-t), 1.04 for Cmax and 1.4 for t(1/2). The median of Tmax was 0.5 hours in American patients as well as Japanese patients. The pharmacokinetics of HFA-BDP in Japanese children with bronchial asthma are reported for the first time and a similarity to those in American children is suggested.

Comparison of the systemic pharmacodynamic effects and pharmacokinetics of salmeterol delivered by CFC propellant and non-CFC propellant metered dose inhalers in healthy subjects

This was a randomised, double-blind, placebo-controlled, cross-over study comparing the systemic pharmacodynamic effects (heart rate and serum potassium) and pharmacokinetics of salmeterol delivered by the non-CFC hydrofluoralkane (HFA) propellant 134a and the CFC propellant (propellant 11/12) metered dose inhalers (MDI) in healthy subjects. At the therapeutic dose (50 microg), salmeterol-mediated systemic pharmacodynamics were equivalent for the HFA and CFC MDIs. Higher doses of salmeterol (150 and 300 microg) produced dose-related beta-agonist pharmacodynamic effects irrespective of the propellant. However, these effects were lower with salmeterol HFA MDI than with the salmeterol CFC MDI at all dose levels. Overall, salmeterol Cmax and AUC(0-t) values were lower for salmeterol HFA compared with salmeterol CFC MDI. At the highest dose (300 microg), where a full pharmacokinetic profile was obtained, exposure to salmeterol delivered by the HFA MDI compared with the salmeterol CFC MDI was 27% and 30% lower for Cmax and AUC(0-t), respectively. Maximum plasma concentrations were generally seen in the first plasma samples taken 5 min after the start of dosing. Salmeterol HFA was well-tolerated. At supratherapeutic doses, adverse events were typical for high-dose salmeterol with fewer adverse events occurring with the HFA compared with the CFC formulation. These data indicate that the salmeterol HFA MDI would not be associated with a significantly different pharmacodynamic, safety and tolerability profile compared with the salmeterol CFC MDI.

Analysis of anions in hydrofluoro ethers by ion chromatography

Hydrofluoro ethers (HFES) are considered to be an ideal cleaning solvent in applications like vapor degreasing and wet cleaning. It is also a good solvent replacement for CFCs (chlorofluorocarbons), HCFCs (hydrochlorofluorocarbons), HFCs (hydrofluorocarbons) and chlorinated solvents because they have a short atmospheric lifetime and low global warming potential. Based upon their properties, hydrofluoro ethers are ideally suited for the demands of the electronics industry. However, the electronics industry requires these solvents to have high purity, especially in the area of residual anions. This paper will present information on an extraction methodology for the transfer of anions from the hydrofluoro ether to water. Then, an analytical method utilizing ion chromatography that is capable of detection of 10 anions (fluoride, acetate, formate, chloride, nitrite, bromide, nitrate, sulfate, oxalate, and phosphate) in the part per billion level will be demonstrated.

Surface Chemistry and Radiation Chemistry of Trifluoroiodomethane (CF3I) on Mo(110)

The surface-induced and electron-induced chemistry of trifluoroiodomethane (CF3I), a potential replacement for chlorofluorocarbons (CFCs) and chlorofluorobromocarbons (halons), were investigated under ultrahigh vacuum conditions (p ∼ 1 × 10-10 Torr) on Mo(110). Results of temperature-programmed desorption (TPD) experiments indicate that dissociative adsorption of CF3I leads only to nonselective decomposition on Mo(110), in contrast to reactions of CF3I on other metal surfaces. Desorption of CF3 radicals and atomic iodine was detected mass spectrometrically during low-energy (10−100 eV) electron irradiation of four monolayer thick films of CF3I condensed at 100 K. Results of postirradiation temperature-programmed desorption experiments were used to identify CF2I2, C2F5I, C2F6, C2F4I2, and CFI3 as electron-induced reaction products of CF3I. Except for CFI3, all of these electron-induced reaction products of CF3I have been previously identified in γ-radiolysis studies, supporting our earlier claim that tempe...

Cardiac sensitization: methodology and interpretation in risk assessment

An increased sensitivity of the heart to endogenous epinephrine (adrenaline), a phenomenon referred to as cardiac sensitization, has long been recognized as a risk during exposure to hydrocarbons, principally halogenated hydrocarbons. Cardiac sensitization, which can result in serious arrhythmia and death, requires a certain critical blood level of both the sensitizing agent and epinephrine. The original research and methods utilized an exogenous epinephrine challenge during inhalation exposure to a chemical to assess cardiac sensitization potential in Beagle dogs. These screening tests were developed about 30 years ago, although in the last 15 years some modifications of these methods have occurred in response to testing chlorofluorocarbon (CFC) replacements. Results from these experimental cardiac sensitization studies have been used for semi-quantitative risk evaluation for occupational exposures but now are being used more quantitatively for regulatory purposes. The risks associated with cardiac sensitization from CFC replacements are unknown but expected to be low based on cardiac sensitization studies in the 1970s where dogs were made to generate their own adrenaline. With the advent of physiologically based pharmacokinetic (PBPK) modeling, greater emphasis is being placed on quantitative risk assessment for cardiac sensitization. In this investigation, we have examined the various methodologies used for detection of cardiac sensitization and discussed their limitations and advantages. In addition, we examined the potential concerns involved in using experimental cardiac sensitization data and PBPK modeling to predict exposure scenarios.

Trifluoroacetylated proteins in liver and plasma of guinea pigs treated with HCFC-123 and halothane

Trifluoroacetylated (TFA)-protein adducts were investigated by immunoblotting in liver and plasma of guinea pigs treated with the hepatotoxic anaesthetic halothane or the chlorofluorocarbon replacement 1,1-dichloro-2,2,2-trifluoroethane (HCFC-123). Male outbred Hartley guinea pigs (320–400 g) were administered HCFC-123 (1, 5, 10 and 15 mmol/kg b.w.) or halothane (positive control, 10 mmol/kg b.w.) i.p. in corn oil. Blood and liver samples were collected 24 h after administration of HCFC-123 or halothane. Immunoreactive bands were demonstrated in liver microsomes at all HCFC-123 and halothane concentrations, and in plasma of animals treated with 10 and 15 mmol/kg b.w. HCFC-123 and 10 mmol/kg b.w. halothane, while no alteration of microsomal P450 content or monooxygenase activities markers of the P450 2A, 2E1 and 2B isoforms was observed. Instead, when HCFC-123 was administered at doses of 1 and 5 mmol/kg b.w., the 2E1-dependent p-nitrophenol hydroxylase activity was enhanced. The presence of TFA-proteins in plasma was always associated with hepatic damage. However, mild liver damage in some animals treated with 1 or 5 mmol/kg b.w. HCFC-123 was not associated with the presence of TFA-proteins in plasma. This indicates a lower threshold dose for the appearance of TFA-proteins or damage in the liver (1 mmol/kg b.w.) than for the presence of TFA-proteins in plasma (10 mmol/kg b.w.), thus suggesting that the presence of TFA-proteins in plasma may be the result of liver damage.