Pesticides halogenated

Bimetallic nanomaterials such as Pd/Fe, Ni/Fe, and Pd/Au are also active catalysts for the degradation of organic contaminants, including halogenated pesticides, nitroaromatics, polychlorinated biphenyls, and halogenated aliphatics (ethenes and methanes) [151]. 

A third type of detector, required for some environmental and biomedical applications, is the electron capture detector (ECD). This detector is especially useful for large halogenated hydrocarbon molecules since it is the only one that has an acceptable sensitivity for such molecules. Thus, it finds special utility in the analysis of halogenated pesticide residues found in environmental and biomedical samples. 

Pytlewski LL, Krevitz K, Smith AB. 1979. Conversion of PCBs and halogenated pesticides into non-toxic materials using a new type of alkali metal reaction. In Eleventh Mid-Atlantic Industrial Waste Conference, Pennsylvania State University, University Park, PA, July 15-17, 1979. University Park, PA Pennsylvania State University, 97-99. 

Many analytes listed in Table 1 have been measured spectrophotometri-cally in seawater for some time, including many metal ions and some gases, although spectrophotometry is the preferred method for only a minority. Some analytes, like alkanes, are spectrophotometrically silent, or do not form colored complexes with other reagents. Similarly, individual nuclides cannot be distinguished by classical spectrophotometry, and many of the other analytes, such as halogenated pesticides and metal alkyls, are more easily determined by other methods, such as gas chromatography with electron capture detection, or emission spectroscopy. Indeed, many of the analytes, such as zinc or copper, are present at trace levels and are not measurable by spectrophotometry. 

Davila-Vazquez G, Tinoco R, Pickard MA et al (2005) Transformation of halogenated pesticides by versatile peroxidase from Bjerkandera adusta. Enzyme Microb Technol 36 223-231... 

Davila et al. [68] reported the transformation of the pesticides bromoxynil, dichlorophen, and pentachlorophenol by the versatile peroxidase from B. adusta. For the three transformed pesticides by versatile peroxidase, an oxidative dehalo-genation was observed, a very important process since the halogenated pesticides are considered more persistent and toxic than the organophosphorus pesticides, because of the carbon-halogen bond. Enzymatic transformation of dichlorophen compound... 

The selectivity of the election capture detector, coupled with its extreme sensitivity (down to 1 pg), makes it very useful for compounds such as tiie benzodiazepines or halogenated pesticides. Alternatively, the great sensitivity of the detector may be utilised by preparing derivatives with reagents such as heptafluorobutjric anhyctiide. For some compounds the sensitivity of tiiis detector may exceed that of the mass spectrometer. 

The most potent interaction of toxicological significance reported to date involves two known animal carcinogens (2). Whether this interaction between chlordecone and CCl results in amplified carcinogenicity has not been tested. The interaction represents a sequential exposure to a halogenated pesticide, chlordecone and a haloalkane, both at individually nontoxic doses (10). 

Table V lists the classes of pesticides of which some members are known to modify the induction of cancer. Halogenated pesticides are by far the most widely studied in this regard. Examples from Insecticides, fungicides, herbicides and other types of agrochemicals fall into these broad chemical classes.

Treatment with sulfuric acid or concentrated base offers an alternative solution for the removal of lipids and other interferences. Because PCBs are generally resistant to sulfuric acid, concentrated sulfuric acid treatment is used for degradation of most aliphatic and many aromatic compounds in environmental samples. Sulfuric acid may affect other compounds such as some halogenated pesticides (e.g., dieldrin) that are determined together with PCBs in one extract. 

Detoxification of Some Halogenated Pesticides by Thiosulfate Salts... 

Method 551.1, Determination of Chlorination Disinfection Byproducts, Chlorinated Solvents, and Halogenated Pesticides/Herbicides in Drinking Water by Liquid-Liquid... 

Oestrogenic activity has been demonstrated in a number of other anthropogenic substances. An example is bisphenol A (see Section 12.9.2), a monomer of polycarbonate and epoxy resins, which can be leached from lacquered plates for cans or dental compositions and seals. Oestrogenic activity is also exhibited by some halogenated pesticides, polychlorinated biphenyls and certain of their hydroxy-lated metabolites, phthalates (used as plastic softeners), veterinary pharmaceuticals and some other xenobiotics, which are referred to in Chapter 12. 

The use of noble metal NPs in water purification for applications other than microbial disinfection was first reported in 2003. The chemistry reported can be summarized as reductive de-halogenation of chlorocarbons (halocarbons in general) in water solutions occurring at room temperature over silver nanoparticles wherein the C-Cl bond is cleaved with the formation of AgCl. UV-visible spectroscopic analysis of this reactivity is shown in Fig. 8A. A series of chemical events occur on the nanoparticle and amorphous carbon is observed as a product. This chemistry was soon extended to halogenated pesticides at high efficiency.A concentration of 50 ppb chlorpyrifos was reduced to less than 0.5 ppb upon passing over a... 

---