Chlorinated hydrocarbons, detection

Hints on the presence of silicone deposits are given by the adhesive strip test (lowering of the adhesion due to silicone) and the foam test (marked formation of foam when the textile sample is shaken with chlorinated hydrocarbons). Detection by means of IR spectroscopy is discussed in Section 8.4.4. 

The performance of SCWO for waste treatment has been demonstrated (15,16). In these studies, a broad number of refractory materials such as chlorinated solvents, polychlorinated biphenyls (PCBs), and pesticides were studied as a function of process parameters (17). The success of these early studies led to pilot studies which showed that chlorinated hydrocarbons, including 1,1,1-trichloroethane /7/-T5-6y,(9-chlorotoluene [95-49-8] and hexachlorocyclohexane, could be destroyed to greater than 99.99997, 99.998, and 99.9993%, respectively. In addition, no traces of organic material could be detected in the gaseous phase, which consisted of carbon dioxide and unreacted oxygen. The pilot unit had a capacity of 3 L/min of Hquid effluent and was operated for a maximum of 24 h. 

Case 2 - The Hyde Park Landfill site, located in an industrial complex in the extreme northwest corner of Niagara, New York, was used from 1953 to 1975 as a disposal site for an estimated 80,000 tons of chemical waste, including chlorinated hydrocarbons. A compacted clay cover was installed in 1978 over the landfill and a tile leachate collection system was installed in 1979. Hazardous compounds such as ortho-, meta- and para-chlorobenzoic acid toluene ortho- and meta-chlorotoluene 3,4-dichlorotoluene and 2,6-dichlorotoluene were detected in the leachate (Irvine et al., 1984). Since 1979, the existing leachate treatment system has used activated carbon as the technology for removing organic carbon. Although... 

Organic solvents have acute narcotic effects. Aromatic and chlorinated hydrocarbons seem to be especially effective. As stated, the combined effect of several organic solvents is usually considered to be additive. However, there is some evidence that the combined effect may in fact be synergistic. The symptoms caused by organic solvents, often called prenarcotic symptoms, resemble those caused by the use of alcohol. A decrease in reaction time and impairment in various psychological performances can be observed. Acute neurotoxicity can also be detected as abnormalities in the electroencephalogram (EEG i, which records the electrical activity of the brain. " ... 

Data gathered from several sites near Niigata, Japan, between April 1989 and March 1992 showed elevated levels of trichloroethylene and other volatile chlorinated hydrocarbons in the winter (Kawata and Fujieda 1993). A rural site in this study had armual mean concentrations between 0.17 and 0.32 ppb, while four industrial sites had mean concentrations between 0.029 and 4.8 ppb. The average trichloroethylene level detected in samples collected from ambient air in the Norwegian Arctic between 1982 and 1983 was 0.007 ppb (Hov et al. 1984). Average concentrations of trichloroethylene in Alaskan Arctic haze between 1980 and 1982 were 0.036 ppb in winter and 0.007 ppb in summer (Khalil and Rasmussen 1983). 

Haberl [8] volatile chlorinated hydrocarbons, PCB and pesticides detected limits for each volatile compounds ... 

Walsh J.E., MacCraith B.D., Meany M., Vos J.G., Regan F., Lancia A., Artjushenko S., Midinfrared fiber sensor for the in-situ detection of chlorinated hydrocarbons, SPIE, 1995 2508 233-242. 

Beyer T., Hahn P., Hartwig S., Konz W., Scharring S., Katzir A., Steiner H., Jakusch M., Kraft M., Mizaikoff B.,, Mini spectrometer with silver halide sensor fiber for in situ detection of chlorinated hydrocarbons, Sensors Actuators B, 2003 90 319 - 323. 

Analysis of PDP data from 1994 to 1999 showed that 73% of approximately 27,000 food samples that had no market claim (conventional or organic) showed detectable residues, while 23% of 127 fresh food samples designated as organic had detectable residue levels (Baker et al., 2002). Unavoidable contamination of some of the organic samples was due to the presence of persistent chlorinated hydrocarbon insecticides, which had been banned several years earlier, but 13% of the organic samples showed residues of pesticides other than the chlorinated hydrocarbon insecticides. 

No correlation has been made between the exact environmental levels of chloroform and the amount of chloroform in the exhaled breath or in the blood. Furthermore, chloroform also can be detected in the breath after exposure to carbon tetrachloride and other chlorinated hydrocarbons (Butler 1961). Therefore, chloroform levels cannot be used as reliable biomarkers of exposure to this chemical. 

Exposure. Methods for detecting chloroform in exhaled breath, blood, urine, and tissues are available. Nevertheless, it is difficult to correlate chloroform levels in biological samples with exposure, because of the volatility and short half-life of chloroform in biological tissues. Several studies monitored chloroform levels in environmentally exposed populations (Antoine et al. 1986 Hajimiragha et al. 1986 Peoples et al. 1979) however, the measured levels probably reflect both inhalation and oral exposure. Moreover, increased tissue levels of chloroform or its metabolites may reflect exposure to other chlorinated hydrocarbons. Studies to better quantitate chloroform exposure would enhance the database. 

Cardiovascular Effects. Most studies of humans exposed to carbon tetrachloride by inhalation have not detected significant evidence of cardiovascular injury, even at exposure levels sufficient to markedly injure the liver and/or kidney. Changes in blood pressure, heart rate, or right- sided cardiac dilation have sometimes, but not always, been observed (Ashe and Sailer 1942 Guild et al. 1958 Kittleson and Borden 1956 Stewart et al. 1961 Umiker and Pearce 1953), and are probably secondary either to fluid and electrolyte retention resulting from renal toxicity, or to central nervous system effects on the heart or blood vessels. Carbon tetrachloride also may have the potential to induce cardiac arrhythmias by sensitizing the heart to epinephrine, as has been reported for various chlorinated hydrocarbon propellants (Reinhardt et al. 1971). 

Berwanger, D. J. Barker, J. F. (1988). Aerobic biodegradation of aromatic and chlorinated hydrocarbons commonly detected in landfill leachates. Water Pollution Research Journal of Canada, 23(3), 460—75. 

Pesticides and Fungicides. Modern pure food regulations require that the food processor be responsible for their finished products. Since so many pesticides and fungicides are used in agriculture, their detection and quantitative analysis are difficult (5, 22). Organophosphorus and chlorinated hydrocarbons are the most common pesticides. When GLC is used for halogens, electron capture or microcoulometric detectors are used for phosphorus, a thermionic flame photometric detector is required. 

The chlorinated hydrocarbon compounds which have recently become of significant interest in chlorinated water supplies can be determined by this method very elegantly and accurately without interference by other potential contaminants using electron-capture detection. With the combination of selectivity and extreme sensitivity of this approach, the parts-per-billion concentrations that are of concern can be directly measured, thus eliminating all concern for loss or introduction of confusing... 

The fluorescent intensities of the E vitamers are highly dependent on the solvent. Polar solvents such as diethyl ether and alcohols provide greater intensities compared with hexane. The fluorescence is negligible when the compounds are dissolved in chlorinated hydrocarbons (137). The inclusion of an ether or an alcohol in the hexane mobile phase increases the sensitivity of vitamin E detection measurably in normal-phase HPLC. 

Plasticizers include the esters of a few aliphatic and aromatic mono and dicarboxylic acids, aliphatic and aromatic phosphorus acid esters, ethers, alcohols, ketones, amines, amides, and non-polar and chlorinated hydrocarbons. These additives are used in various mixtures. For their separation and qualitative detection, thin-layer chromatography (TLC) is preferred. Usually Kieselgur plates, 0.25 mm thick, activated at 110°C for 30 min, in the saturated vapor are used. Methylene chloride and mixtures of diisopropyl ether/petether at temperatures between 40 to 60°C have been successfully used as the mobile phase. Refer to Table 1. 

The second approach was realized by direct injection of microliter quantities of liquid into the internally polymer coated HWG, which is a useful approach if only limited amounts of sample are available. After sufficient exposure time ensuring partitioning of the analyte into the polymer coating, the HWG was purged with air to remove the remaining liquid sample and then inserted into the FT-IR. This approach was used to study several chlorinated hydrocarbons and chlorinated aromatic amines. In this approach, the limits of detection for these compounds were determined to be approximately 1 ppm. However, in both approaches, the analysis is a two-step process requir-... 

Further optimization was performed by adapting the SCMS/HWG sensing system to the determination of several chlorinated hydrocarbons. Calculated detection limits less than 50 and 1 ppm (v/v) were determined for dichloromethane and chloroform, respectively. 

Pesticides can be analyzed on a C18 column, the chlorinated hydrocarbon type (chlordane) at 80% An/water UV, 220 nm, the carbamate type (sevin) at 40% An/water UV, 254 nm, and the organic phospahate (malathion) at 50% An/water with UV, 192 nm or with a CAD. The organic phosphate types are hard to detect at low concentration and various phosphate analysis techniques have been evaluated. LC/MS, where available, is the technique of choice for analyzing all of these pesticides, but especially the organic phosphates, in a general gradient HPLC scheme. 

A combination of electrochemical methods and SERS is used to detect chlorinated hydrocarbons in aqueous solutions [28], Electrochemistry prepares the surface of a copper electrode for SERS and concomitantly concentrates the analyte on the surface of the electrode, possibly by electrophoretic processes. Detection sensitivity of <1 ppm for trichloroethylene, for example, was achieved. 

The non-polar chlorinated hydrocarbon pesticides are routinely quantified using gas chromatography (GC) and electron capture(EC) detection. Alternate detectors include electrolytic conductivity and microcoulometric systems. Organophosphate pesticides which are amenable to GC are responsive to either the flame photometric detector (FPD) or the alkali flame detector (AFD). Sulfur containing compounds respond in the electrolytic conductivity or flame photometric detectors. Nitrogen containing pesticides or metabolites are generally detected with alkali flame or electrolytic conductivity detectors. 

---