Organochlorine pesticides volatilization

Waggot and Britcher [38] have discussed experimental considerations in the determination of organic carbon content of sewage effluent. Close attention is paid to the determination of particular classes of organic compounds in sewage including carbohydrates, amino acids, volatiles, steroids, phenols, surface active materials, fluorescent materials, organochlorine pesticides and ethylene diamine tetracetic acid. 

Organochlorine pesticides and OPPs have been determined mainly using GC, because of the stability and volatility that most of them show under chromatographic conditions and, particularly, the availability of element-selective detectors that display high selectivity for OCPs (electron-capture detector, ECD), and OPPs (flame photometric detector, FPD, and nitrogen phosphorus detector, NPD). Mass spectrometry-based detection is also more popular in GC than in HPLC (1,2,12,16). 

The results presented in Table VI for the 42 organochlorine pesticides extracted from spiked sand indicate that SFE with carbon dioxide worked reasonably well for 35 of the 42 compounds (recovery > 50 percent) from those 35 compounds, 30 compound had recoveries > 70 percent. Among the seven compounds with recoveries < 50 percent, two are very volatile (DBCP and hexachlorocyclopentadiene). Three of the remaining five compounds (chlorthalonil, captan, and endosulfan sulfate) gave very poor recoveries with carbon dioxide alone, probably because of their polarity however, in other experiments we have recovered them quantitatively from spiked sand with carbon dioxide modified with 10 percent methanol (1). Chlorobenzilate recoveries were poor, even when we used carbon dioxide with 10 percent methanol, and captafol was not tested with the carbon dioxide/methanol combination. 

Many processes are operative in the environment that contribute to the regional elimination of a contaminant by altering its distribution. Contaminants with sufficiently high vapor pressure can evaporate from contaminated terrestrial or aquatic compartments and be transferred through the atmosphere to new locations. Such processes of global distillation are considered largely responsible for the worldwide distribution of relatively volatile organochlorine pesticides such as lindane and hexachlorobenzene. Entrainment by wind and upper atmospheric currents of contaminant particles or dust onto which the contaminants are sorbed also contribute to contaminant redistribution. Sorption of contaminant to suspended solids in an aquatic environment with commensurate sedimentation can result with the removal of contaminants from the water... 

Accelerated solvent extraction is a new technique for the extraction of a range of organic pollutants from soils and related material. The technique is based on the use of a solvent or combination of solvents to extract organic pollutants at elevated pressure and temperature from a solid matrix. The range of organic pollutants for which the technique is proposed includes semi volatile compounds, organochlorine pesticides, organophosphorous pesticides, chlorinated herbicides, polychlorinated biphenyls and polycyclic aromatic hydrocarbons [66-69]. 

New York Developing capacity to monitor for polyaromatic hydrocarbons (PAHs) in urine, polybrominated diphenyl ethers (PBDEs) in serum, organochlorine pesticides in serum, volatile organic compounds (VOCs) in blood, cotinine in saliva, trace elements in blood and urine, inorganic mercury in blood and to generate data on exposure to persistent organic pollutants (CDC 2005). 

Total Recoverable Petroleum Hydrocarbons Volatile PAHs Less Volatile PAHs Organochlorine Pesticides PCBs... 

A variety of methods has been devised for the confirmation of heptachlor residues (Table II). The presence in the heptachlor molecule (Figure 1) of a reactive allylic chlorine atom has been the basis of three confirmatory tests based on its ease of replacement. Reaction with a silver acetate-glacial acetic acid mixture produced 1-acetoxychlordene which, with the GLC conditions used, had a retention time close to heptachlor epoxide 44). Of the common organochlorine pesticides, only heptachlor reacted quantitatively. Endrin reacts to a small extent with the glacial acetic acid to give a secondary endrin ketone peak. When the reaction of heptachlor with silver salts was extended to silver carbonate in aqueous alcohol, 1-hydroxychlordene was obtained which can easily be converted to the more volatile and GG-responsive silyl ether. Unfortunately, this silyl ether has a Rt identical to aldrin. With silver carbonate, hepta-... 

Automated Soxhlet extraction Polychlorinated biphenyls, organochlorine pesticides and semi-volatiles from soils, relatively dry sludges and solid wastes Allows equivalent extraction efficiency to Soxhlet extraction in 2 h... 

This book provides methods for measuring the major contaminants that cause "sick building syndrome, inducting volatile organic compounds, carbon monoxide and carbon dioxide, nitrogen dioxide, organochlorine pesticides, particulates, and other compounds. 

Chemical dechlorination processes use reduction reagents to remove chlorine atoms from hazardous chlorinated molecules to leave less hazardous compounds. Dechlorination can be used to treat soils and waste contaminated with volatile halogenated hydrocarbons, polychlorinated biphenyls and organochlorine pesticides. 

In 1994 Lopez-Avila et al., published their work to expand the use of MAE to 187 volatile and semivolatile organic compounds from soils. The compounds included polyaromatic compounds, phenols, organochlorine pesticides and organophosphorus pesticides. MAE uses microwaves that can easily penetrate into the sample pores causing the solvent trapped in the pores to heat evenly and rapidly. In contrast to conventional heating MAE is a promising technique because ... 

Thermal desorption involves volatilization of contaminants from soil by heating the soil in various kinds of drying kilns, and is the solid phase analog of air or stream stripping. Temperatures in range 200-500 °C are used. The off-gases must then be treated before release to the atmosphere. This method can be applied to hydrocarbon-contaminated soils and to soils contaminated with organochlorine pesticides (Bunce, 1994). 

Recent observations of the global distribution of persistent contaminants such as PCBs and some organochlorine pesticides emphasize the importance of defining the tendency of compounds to move into the vapor phase. This transition not only provides access to active degradation processes (see Photochemical Processes, Chapter 6), but it also results in a broader distribution through the influence of atmospheric processes. The PCBs and related compounds would not be considered volatile by usual criteria, however, it will be demonstrated that evaporation of a compound is influenced by its environment that is, compounds that might have little tendency to evaporate as the pure compound may be lost rapidly from water. Also, the magnitude of the response may reflect the area over which the compound is distributed. 

Figure 1.2 Overview of the EPA s organics protocol. VOCs, volatile organics SVOCs, semivolatile organics OCs/PCBs, organochlorine pesticides/poly-chlorinated biphenyls HS-GC-FID, static headspace coupled to gas chromatography and flame ionization detection LLE, liquid-liquid extraction LSE, liquid-solvent extraction or solvent leaching from solid matrices GC-ECD, gas chromatography and electron-capture detection GC-MS, gas chromatography and mass spectrometry RP-SPE, reversed-phase solid-phase extraction.

Determination of Priority Pollutant Non-Volatile Organochlorine Pesticides in Contaminated Groundwater Comparison of Sample Preparation Methods—pLLE versus Solid-Phase Extraction Techniques ... 

Organochlorine pesticides = A unique class of pesticides because of their cyclic structure, number of chlorine atoms, and low volatility. They can be classified into four categories dichlorophenyl-ethanes (e.g., DDT), cyclodienes, chlorinated benzenes (e.g., hexachlorobenzene (HCB)), and cyclohexanes (e.g., hexachlorocyclohexane (HCH)). 

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