Polychlorobiphenyls, soils

Fava F, D Di Gioia (1998) Effects of Triton X-100 and quillaya saponin on the ex situ bioremediation of a chronically polychlorobiphenyl-contaminated soil. Appl Microbiol Biotechnol 50 623-630. 

Detectors range from the universal, but less sensitive, to the very sensitive but limited to a particular class of compounds. The thermal conductivity detector (TCD) is the least sensitive but responds to all classes of compounds. Another common detector is the flame ionization detector (FID), which is very sensitive but can only detect organic compounds. Another common and very sensitive detector is called electron capture. This detector is particularly sensitive to halogenated compounds, which can be particularly important when analyzing pollutants such as dichlorodiphenyltrichloroethane (DDT) and polychlorobiphenyl (PCB) compounds. Chapter 13 provides more specific information about chromatographic methods applied to soil analysis. 

Spectrofluorimetric methods are applicable to the determination of aliphatic hydrocarbons, and humic and fulvic acids in soil, aliphatic hydrocarbons polyaromatic hydrocarbons, optical whiteners, and selenium in non-saline sediments, aliphatic aromatic and polyaromatic hydrocarbons and humic and fulvic acids in saline sediments. The only application found in luminescence spectroscopy is the determination of polychlorobiphenyl in soil. Generally speaking, concentrations down to the picogram (pg L 1), level can be determined by this technique with recovery efficiencies near f00%. 

This technique has been used for the determination of polychlorobiphenyls, polychlorodibenzo-p-dioxins, polychlorodibenzofurans, alkyl phosphates, chlorinated insecticides, organophosphorus insecticides, triazine herbicides. Dacthal insecticide, insecticide/herbicide mixtures, mixtures of organic compounds and organotin compounds in soils, and polyaromatic compounds, polychlorobiphenyls, chlorinated insecticides and organotin compounds in non-saline sediments and anionic surfactants in sludges. 

This technique has been applied to the determination of heteroaromatic compounds, anthropogenic hydrocarbons, polymers, haloaromatic compounds in soils, polyaromatic hydrocarbons, cationic surfactants and polychlorobiphenyls and mixtures of organic compounds in non-saline sediments and bacteria identification in sludges. 

This technique has been used to determine the following types of organic compounds in soil polychlorobiphenyls, chlorinated insecticides, triazine herbicides, paraquat and diquat. 

Another growing technique is super-critical fluid chromatography. Recent references to soil analysis include the following applications aliphatic hydrocarbons, polyaromatic hydrocarbons, polychlorobiphenyls, dioxins, alkyl and aryl phosphates, chloro, organophosphorus, triazine, substituted urea, phenoxy acetic acid, Dacthal herbicides and insecticides and mixtures of herbicides and pesticides and mixtures of organic compounds. 

Electrophoretic and isotachoelectrophoretic techniques are gaining in popularity in soil analysis with applications to polyaromatic hydrocarbons, polychlorobiphenyls, tetrahydrothiophene and triazine herbicides, Paraquat and Diquat and growth regulators. Other lesser-used techniques include spectrophotometric methods (five determinants), spectrofluorimetric methods (two determinants), luminescence methods (one determinant), titration methods (one determinant), thin-layer chromatography (five applications), NHR spectroscopy (two applications) and enzymic immunoassays (one determinant). 

Lagenfeld et al. [48] studied the effect of temperature and pressure on the supercritical fluid extraction efficiencies of polyaromatic hydrocarbons and polychlorobiphenyls in soils. At 50°C raising the pressure from 350 to 650atm had no effect on recoveries. 

Recovery of polychlorobiphenyls from soil samples obtained in spiking experiments was 100% while that of chlorinated insecticides ranged from 81.5% (Heptachlor) to 96.3% (Dieldrin). A limit of detection of 6.5ppb was obtained from aroclors 1254 and 1260. 

Rabbat et al. [50] carried out an evaluation of a thermal desorption gas chromatographic-mass spectrometric method for the on-site detection of polychlorobiphenyls in hexane extracts of soils. Down to 35mg kg-1 of polychlorobiphenyl was detected in soil samples. 

Brady et al. [52] have discussed pressure-temperature phase diagrams for carbon dioxide polychlorobiphenyls and examined the rate process of desorption from soils. Supercritical carbon dioxide was used to extract polychlorobiphenyls and DDT and Toxaphene from contaminated soils. 

Hawthorne et al. [53] compared supercritical extraction with chlorodifluoromethane, nitrous oxide and carbon dioxide for the extraction of polychlorobiphenyls and polyaromatic hydrocarbons from soil. Chlorodifluoromethane provided the highest recoveries while methanol modified carbon dioxide gave a 90% recovery of polychlorobiphenyls from soil. 

Von Bavel et al. [55] used a solid phase carbon trap in conjunction with supercritical fluid chromatography for the simultaneous determination of polychlorobiphenyls, pesticides, polychlorodibenzo-p-dioxins and polychlorodibenzofurans in soils. 

Yang et al. [56] used subcritical water to extract polychlorobiphenyls from soil and sediments. Quantitative recovery of polychlorobiphenyls was observed at water temperatures of 250 and 300°C when the pressure was reduced to 50atm at 300°C the extraction was complete within 5min. 

Supercritical fluid extraction with carbon dioxide has been applied to the determination of polychlorobiphenyls in soil [113]. 

McMurtrey et al. [65] investigated the feasibility of determining polychlorinated biphenyls adsorbed on soils and sediments, by a procedure involving pyrolytic desorption at 1000°C, followed by gas chromatography and mass spectrometry. The procedure was capable of demonstrating the presence of polychlorobiphenyls on air-dried sediment at the lOppm level. 

The procedure [56] involving subcritical water extraction of polychlorobiphenyls from soils described in section 5.6.1.4 has also been applied to sediments. 

The electron capture negative ion chemical ionization mass spectrometric method [58] discussed in section 5.6.1.6 for the determination of polychlorobiphenyls in soils has also been applied to sludges. 

Representative multiple ion mass chromatograms of soil samples are presented in Fig. 5.4. These gas chromatography-mass spectrometric determinations of polychlorodibenzo-p-dioxin and polychlorodibenzofurans, and non-ortho polychlorobiphenyls in differing types of samples serve to exemplify the versatility of the procedure for such analyses. The gas chromatography-mass spectrometric data were usually uncluttered by extraneous components, and interpretation of the data was routinely straightforward. 

Von Bavel et al. [55] have developed a solid phase carbon trap (PX-21 active carbon) for the simultaneous determination of polychlorodibenzo-p-dioxins and polychlorodibenzofurans also polychlorobiphenyls and chlorinated insecticides in soils using superfluid extraction liquid chromatography for the final determination. Supercritical fluid extraction with carbon dioxide has been applied to the determination of dioxins in soil [114],... 

The method described by Teichman et al. [15] and discussed in section 9.1.1.2 for the determination of chlorinated insecticides and PCBs in soils has also been applied to sediments. The procedure involves adsorption chromatography on alumina and charcoal, elution with increasing fractional amounts of hexane on alumina columns, and with acetonediethyl ether and benzene on charcoal columns. The polychlorobiphenyl and pesticides are then determined by gas chromatography on the separate elutes without interference. 

Wegmann and Hofstee [43] have developed a capillary gas chromatographic method for the determination of organochlorine insecticides in river sediments. Bottom soils from rivers, collected in slow current areas may contain high concentrations of organochlorine insecticides and polychlorobiphenyls. When the current moves more rapidly or benthic animals become more active, these compounds are stirred into the water along with suspended particles and become accessible to organisms that live in the bottom layer. 

Table 9.7 presents the results of analysis of organochlorine insecticides and polychlorobiphenyls using copper, mercury and tetrabutyl ammonium sulphate to desulphurize bottom soil extracts. 

Namiesnik et al. [33] have reviewed the analysis of soils and sediments for organic contaminants. They discuss methods of sample preparation and isolation-preconcentration prior to instrumental determination. Compound classes discussed include volatile organic compounds, polychlorobiphenyls, polyaromatic compounds, pesticides and polychlorodibenzo-p-dioxins and polychlorodibenzofurans. 

Hawari, J., Demeter, A., and Samson, R. Sensitized photolysis of polychlorobiphenyls in alkaline 2-propanol dechlorination of Aroclor 1254 in soil samples by solar radiation, Environ. Sci. Technol., 26(10) 2022-2027, 1992. 

Sun, S. Boyd, S. A. (1991). Sorption of polychlorobiphenyl (PCB) congeners by residual PCB-oil phases in soils. Journal of Environmental Quality, 20, 557-61. 

Boyd, S. A. Sun, S. (1990). Residual petroleum and polychlorobiphenyl oils as sorptive phases for organic contaminants in soils. Environmental Science Technology, 24,142—4. 

Hubert et al. [101] state that accelerated solvent extraction compared to alternatives such as Soxhlet extraction, steam distillation, microwave extraction, ultrasonic extraction and, in some cases, supercritical fluid extraction is an exceptionally effective extraction technique. Hubert et al. [ 101 ] studied the effect of operating variables such as choice of solvent and temperature on the solvent extraction of a range of accelerated persistent organic pollutants in soil, including chlorobenzenes, HCH isomers, DDX, polychlorobiphenyl cogeners and polycyclic aromatic hydrocarbons. Temperatures ofbetween 20 and 180 °C were studied. The optimum extraction conditions use two extraction steps at 80 and 140 °C with static cycles (extraction time 35 minutes) using toluene as a solvent and at a pressure of 15 MPa. 

Other applications of subcritical water extraction-solid-phase microextraction are the determination of terbuthylazine and its metabolites [123], polycyclic aromatic hydrocarbons [124,125] and polychlorobiphenyls [63]. Yang and Her [193] collected 1-chloronaphthylene, nitrobenzene and 2-chloro-toluene in soil on a hydrophobic polyisobutylene disc prior to analysis by attenuated total reflectance Fourier transform infrared spectroscopy. 

Budzinski et al. [142] have reported an infrared spectroscopic method for the determination of down to 200-300 ppb of semivolatiles such as polycyclic aromatic hydrocarbons and polychlorobiphenyls in soil. 

A wide variety of techniques have been employed to extract polychlorobiphenyls from soil prior to analytical determination (Table 4.1). 

Table 4.1. Extraction methods for the isolation of polychlorobiphenyls from soil (from author s own files)...

Benicka et al. [ 183] used multidimensional gas chromatography to separate the atropisomers of polychlorobiphenyl congeners in extracts of soil. The correct enanatiomeric ratio was determined from the peak areas obtained by deconvolution of the chromatograms. 

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