1.2- Dibromoethane samples

The double titration method, which involves the use of ben2ylchloride, 1,2-dibromoethane, or aUyl bromide, determines carbon-bound lithium indirectly (101,102). One sample of the //-butyUithium is hydroly2ed directly, and the resulting alkalinity is determined. A second sample is treated with ben2ylchloride and is then hydroly2ed and titrated with acid. The second value (free base) is subtracted from the first (total base) to give a measure of the actual carbon-bound lithium present (active base). 

Analytical Methods for Determining 1,2-Dibromoethane in Environmental Samples... 

Radioactivity ( H or "C-1,2-dibromoethane) was detected in spermatozoa collected approximately 1 week following the initial oral dose (Amir 1973). These results indicate that 1,2-dibromoethane exerts spermicidal action during the process of spermiogenesis and sperm maturation. This conclusion was supported by the evidence that the percentage of sperm abnormalities was highest when little 1,2-dibromoethane radioactivity could be detected in sperm. In addition, reduction in sperm concentration was more pronounced in adult bulls than in young bulls, and the period of recovery was longer in adult animals (Amir 1975). In another study, bulls were fed 2 mg/kg/day 1,2-dibromoethane for 12 months followed by 4 mg/kg 1,2-dibromoethane every other day until they reached the age of 14-16 months. The semen samples examined revealed low sperm density, structural abnormalities, and low mobility (Amir and Volcani 1965). Sperm production returned to normal as early as 10 days postexposure (Amir and Lavon 1976 Amir et al. 1977). 

Primary biomarkers of exposure are the presence of 1,2-dibromoethane in blood or exhaled breath or excretion of specific metabolites in urine. In humans exposed to toxic levels of 1,2- dibromoethane (Letz et al. 1984), the parent compound was not measured in blood samples collected before death. However, two exposed individuals had elevated levels of serum bromide ions. This elevation is likely to have resulted from debromination of 1,2-dibromoethane during its metabolism. Elevated serum bromide is not specific to 1,2-dibromoethane exposure, but, rather, it is indicative of exposure to classes of brominated chemicals. 

Dibromoethane has been widely released to the environment mainly as a result of the historical use of the compound as a gasoline additive and a fumigant (Fishbein 1979). The compound has also been released from industrial processing facilities. For example, 1,2-dibromoethane was found in air, water, soil, and sediment samples taken near industrial bromine facilities in El Dorado and Magnolia, Arkansas, in 1977 (Pellizzari et al. 1978). 

Dibromoethane has been detected in an estimated 0.23% of the groundwater samples analyzed for the 2,783 hazardous waste sites participating in the Contract Laboratory Program (CLP) a positive geometric mean concentration value was not reported. 1,2-Dibromoethane has not been detected in surface water samples taken at hazardous waste sites (CLPSD 1988). Note that the CLP Statistical Database (CLPSD) includes data from both NPL and non-NPL sites. 

Dibromoethane has also been detected in ambient air samples collected at two hazardous waste sites in New Jersey at geometric mean concentrations of 20- 50 ppt the maximum value reported was 6,710 ppt (La Regina et al. 1986). 

Long-range transport of 1,2-dibromoethane from industrialized areas may have been the source of the compound found in ambient air samples collected in the Arctic by Rasmussen and Khalil (1984). 

Natural production was speculated to be the source of 1,2-dibromoethane found in ambient air samples collected from open areas of the North and South Atlantic Ocean by Class and Ballschmitter (1988) concentration levels were reported to be less than 0.001-0.003 ppt. 

Dibromoethane residues in foods have decreased since the use of the compound as a fumigant was banned by EPA. For example. Daft (1989) reported finding 1,2-dibromoethane in only 2 of 549 samples of fatty and nonfatty foods analyzed for fumigant residues in a recent survey. 

Dibromoethane was detected in samples of peanut butter and whiskey at a mean concentration of 7 ng/g (range 2-11 ng/g). Historical foodstuff residue levels have been reviewed by EPA (1983). 

The purpose of this chapter is to describe the analytical methods that are available for detecting and/or measuring and monitoring 1,2-dibromoethane in environmental media and in biological samples. The intent is not to provide an exhaustive list of analytical methods that could be used to detect and quantify 1,2-dibromoethane. Rather, the intention is to identify well-established methods that are used as the standard methods of analysis. Many of the analytical methods used to detect... 

High-resolution GC equipped with an appropriate detector is the most common analytical technique for determining the concentrations of 1,2-dibromoethane in air, water, wastewater, soil, leaded gasoline, and various foods (e.g., grains, grain-based foods, beverages, and fruits). The choice of a particular detector will depend on the nature of the sample matrix, the detection limit, and the cost of the analysis. Because volatile organic compounds in environmental samples may exist as complex mixtures or at very low concentrations, concentrations of these samples prior to quantification are... 

Gas purging and trapping is the most commonly used method for the preconcentration of 1,2-dibromoethane from water, waste water, soil, and various foods. This method also provides a preliminary separation of 1,2-dibromoethane from other less volatile and nonvolatile components in the samples, thereby alleviating the need for extensive separation of the components by a chromatographic column prior to quantification. 

The best sensitivity for 1,2-dibromoethane quantification is obtained by either electron capture detector (ECD) or Hall electrolytic conductivity detector (HECD) in the halide detection mode, since these detectors are relatively insensitive to nonhalogenated species and very sensitive to halogenated species. Another common detection device is a mass spectrometer (MS) connected to a GC. The GC/MS combination provides unequivocal identification of 1,2-dibromoethane in samples containing multiple components having similar GC elution characteristics (see Table 6-2). To date, GC equipped with either ECD or HECD has provided the greatest sensitivity for detecting... 

Dibromoethane can be isolated from soil samples by liquid-liquid extraction and subsequent quantification by GC/MS (Sawhney et al. 1988). Low ppb levels of 1,2-dibromoethane in soil were reported using this technique. 

Sample collection and preparation for the analysis of 1,2-dibromoethane in foods includes the purge-and-trap method, headspace gas analysis, liquid-liquid extraction, and steam distillation (Alleman et al. 1986 Anderson et al. 1985 Bielorai and Alumot 1965, 1966 Cairns et al. 1984 Clower et al. 1985 Pranoto-Soetardhi et al. 1986 Scudamore 1985). GC equipped with either ECD or HECD is the technique used for measuring 1,2-dibromoethane in foodstuffs at ppt levels (Clower et al. 1985 Entz and Hollifield 1982 Heikes and Hopper 1986 Page et al. 1987 Van Rillaer and Beernaert 1985). 

Vinyl bromide may form in air as a degradation product of 1,2-dibromoethane. It may also be released to the environment from facilities which manufacture or use vinyl bromide as a flame retardant for acrylic fibres. Vinyl bromide has been qualitatively identified in ambient air samples (United States National Library of Medicine, 1998a)... 

Before extraction, soil and sediment samples may be dried, for example, by freeze-drying — provided that volatile compounds are not to be analyzed — or by mixing with anhydrous sodium sulfate and extraction in a Soxhlet apparatus. It should, however, be noted that it has frequently been found advantageous to add low concentrations of water, and this is consistent with the finding that addition of water to dry soils inhibits sorption of PAHs (Karimi-Lotfabad et al. 1996). If wet samples are to be analyzed directly, acetonitrile, propan-2-ol, or ethanol may be employed first, and these may be valuable in promoting the chemical accessibility of substances sorbed onto components of the matrices the analyte may then be extracted into water-immiscible solvents and the water phase discarded. Alternatively, if the analyte is sufficiently soluble in, for example, benzene, the water may be removed azeotropically in a Dean Stark apparatus and the analyte then extracted with the dry solvent. Analytes may, however, be entrapped in micropores in the soil matrix so that, for example, recovery of even the volatile 1,2-dibromoethane required extraction with methanol at 75°C for 24 h (Sawhney et al. 1988). 

Smith and Dawson [3] determined traces of ether linkages in polyethylene glycol and polypropylene glycol by reacting the sample with hydrobromic acid then determining the dibromoethane and dibromopropane fission products by gas chromatography. 

Dibromoethane 23 2 Unsatisfactory resistance Diakon ICI Specimen Small, unstressed samples... 

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