Chlorinated insecticides and polychlorobiphenyls

Work on the determination of chlorinated insecticides has been almost exclusively in the area of gas chromatography using different types of detection systems, although a limited amount of work has been carried out using liquid chromatography and thin layer chromatography. 

By its nature, gas chromatography is able to handle the analysis of complex mixtures of chlorinated insecticides. It is not surprising therefore, that much of the published work discussed in this section is concerned with the analyses of mixtures of different types of chlorinated insecticides as found in enviroiunental samples. Work on the determination of individual insecticides is reported at the end of ttiis section. 

The previous pages de t with methods for PCBs alone. In actual practice, envirorunental samples which are contaminated with PCBs are also highly likely to be contaminated with chlorinated insecticides. Many reports have appeared discussing co-interference effects of chlorinated insecticides in the determination of PCBs and vice versa and much of the published work takes account of this fact by dealing with the analysis of both types of compounds. This work is discussed below. 

Various solvents have been used for the preliminary separation of chlorinated insecticides from non scdine waters prior to gas chromatographic analysis. The most commonly used solvents include hexane, petroleum ether, mixtures of hexane and benzene or toluene, benzene, diethyl ether, methylene dichloride acetonitrile (Table 15.4). 

Brodtmann [120] carried out a long-term study on the qualitative recovery efficiency of the carbon adsorption method versus that of a continuous liquid-liquid extraction method for several chlorinated insecticides. Comparative results obtained by electron capture gas chromatography indicate that the latter method may be more efficient. 

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Erikson and Pellizzari [77] analysed municipal sewage samples in the USA by a gas chromatography-mass spectrometry-computer technique for chlorinated insecticides and polychlorobiphenyls. 

Other applications of gas chromatography to the determination of chlorinated insecticides and polychlorobiphenyls in non saline waters are discussed in Table 15.9. 

Polychlorobiphenyls Chlorinated insecticides and polychlorobiphenyls Chloroligno sulphonic acids... 

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. 

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. 

In non-saline sediments aliphatic and polyaromatic hydrocarbons, phthalate esters carboxylic acids, uronic acid aldoses chloroaliphatics haloaromatics chlorophenols chloroanisoles polychlorobiphenyls polychlorodibenzo-p-dioxins poychlorodibenzofurans various organosulphur compounds, chlorinated insecticides, organophosphorus insecticides mixtures of organic compounds triazine herbicides arsenic and organic compounds of mercury and tin. 

In sludge anionic and non-ionic surfactants carboxylic acids hhydroxybutyrate hydroxy valerate chloroaliphatic compounds chlorophenols polychlorobiphenyls 4-nitrophenol mixtures of organic compounds chlorinated insecticides, phenoxy acetic acid type herbicides and organotin compounds. 

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

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. 

Goerlitz and Law [59] determined chlorinated insecticides in sediment and bottom material samples, which also contained polychlorobiphenyls by extracting the sample with acetone and hexane. The combined extracts were passed down an alumina column. The first fraction (containing most of the insecticides and some polychlorinated biphenyls and polychlorinated naphthalenes) was eluted with hexane and treated with mercury to precipitate sulphur. If the polychlorinated hydrocarbons interfered with the subsequent gas chromatographic analysis, further purification on a silica gel column was necessary. 

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],... 

Mattson and Nygren [57] have described the chromatographic procedure for the determination of polychlorobiphenyls and some chlorinated insecticides in sewage sludge. The capillary column is coated with silicone oil SF 96. 

McIntyre et al. [58, 59] described a method for the analysis of polychlorobiphenyls and chlorinated insecticides in sewage sludges in which homogenized samples are extracted with hexane, concentrated and cleaned up on an alumina/alumina plus silver nitrate column and eluted with hexane. After concentration of the eluent, polychlorobiphenyl and organochlorine compounds were determined by a silica gel chromatographic procedure and gas chromatography. 

Polychlorobiphenyls and chlorinated insecticides Silica gel 0.02-0.9 (organochlorine insecticides) 0.5-0.9pg L 1 (polychlorobiphenyls) [38]... 

Other organic compounds that have been determined in sewage effluents include the following (see Table 15.13) hydrocarbons, alcohols, carboxylic acids, esters, chlorobenzenes, nitrosamines, ethylene diamine tetraacetic acid, nitriloacetic acid, organophosphorus compounds, linear alkyl benzene sulphonates, methyl mercaptan, polychlorobiphenyls and chlorinated insecticides. 

The determination of polychlorobiphenyls and chlorinated insecticides in waste waters is also reviewed in Table 15.14. 

Gas chromatography has been applied to the determination of a wide range of organic compounds in trade effluents including the following types of compounds which are reviewed in Table 15.15 aromatic hydrocarbons, carboxylic acids aldehydes, non ionic surfactants (alkyl ethoxylated type) phenols monosaccharides chlorinated aliphatics and haloforms polychlorobiphenyls chlorlignosulphonates aliphatic and aromatic amines benzidine chloroanilines chloronitroanilines nitrocompounds nitrosamines dimethylformamide diethanolamine nitriloacetic acid pyridine pyridazinones substituted pyrrolidones alkyl hydantoins alkyl sulphides dialkyl suphides dithiocaibamate insecticides triazine herbicides and miscellaneous organic compounds. 

Polychlorobiphenyls and Hexane chlorinated insecticides Electron capture Sample clean-up on alumina-silver nitrate and silica gel [635]... 

With the application of electron-capture (EC) and micro-coulometric detection to gas chromatograph effluents from i960, the era of the measurement of nothing in everything had arrived and the environmental controversy was truly on. It was easier to make an effective EC detector than to interpret the analytical results correctly and many of the identifications of chlorinated insecticide (OC) residues made in the early 1960s are undoubtedly suspect, especially since it was found in 1966 that widespread polychlorobiphenyl (FCB) contamination in the bio-sphere can simulate OC in gas chromatographic analysis. 

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