Organophosphorus pesticides malathion

Controlled-release solid formulations of selected volatile organophosphorus pesticides (malathion, DDVP, sumithion, chlorpyriphos, and sulprofos) were studied by Szente [33]. These solid formulations exhibited negligible vapor pressure and preserved their entrapped pesticide content even at elevated temperature. Malathion and chlorpyriphos formulations showed increased physical stability, and resulted in an effective masking of the unpleasant smell while the complex formulations existed as dry solid. Sulfluramid is an expensive insecticide that is lost by volatilization, but complexation to j8-CyD reduced the loss [21]. 

Among the best known organophosphorus pesticides are malathion, parathion, schradan and dimefox. 

Five organophosphorus pesticides were chosen that could be iso-thermally and simultaneously analyzed by gas chromatography using an N-P TSD detector. They are all currently commercially used and exhibit a wide range of physicochemical properties (Table I). Also influencing the choice of these pesticides was the fact that volatilization data measured from soil and water under controlled laboratory conditions are scarce for methyl parathion, parathion, and diazinon (14-17), and are not available for malathion and mevinphos. Technical mevinphos (60% E-isomer, Shell Development Co.), diazinon (87.2%, Ciba-Geigy Corp.), and malathion (93.3%, American Cyanamld), and analytical grade methyl parathion (99%, Monsanto) and parathion (98%, Stauffer Chemical Co.) were used. 

Gratzel et al. demonstrated a wide variety of organophosphorus pesticides, including paraoxon, parathion, and malathion, which possess aromatic side chains and/or sulfur atoms can be totally decomposed into carbon dioxide and the corresponding mineral acids by irradiation in a solar simulator in the presence of anatase TiO2 suspensions [41]. The balanced equation based on carbon dioxide evolution for the mineralization of parathion is represented by Eq. (6) ... 

The first six organophosphorus and chlorinated organophosphorus pesticides dominate wheat-based products. Exhibit 7 shows that virtually all wheat-based products are, at a minimum, contaminated with malathion and chlorpyrifos-methyl. These data also suggest that although corn-based products can contain malathion and chlorpyrifos-methyl, they are much less likely to be contaminated by the first six organophosphorus and chlorinated organophosphorus pesticides. 

Barr, D.B., and J. Angerer. In press. Potential uses of biomonitoring data A case study using the organophosphorus pesticides chlorpyrifos and malathion. Environ Health Perspect. [online]. Available http //ehp.niehs.nih.gov/docs/2006/9062/abstract.html [accessed Aug. 21,2006],... 

The technique was used to determine several organophosphorus pesticides (E)- and (Z)-Mevinphos, Dichlorvos, Azinphos-methyl, Azinphosethyl, Parathion-methyl, Parathion-ethyl, Malathion, Fenitrothion, Fenthion, Chlorfenvinphos and Diazinon, in groundwater. 

Walker, W.W., Stojanovic, B J. (1973) Microbial versus chemical degradation of malathion in soil. J. Environ. Qual. 2, 229-232. Wang, T.C., Hoffman, M.E. (1991) Degradation of organophosphorus pesticides in coastal water. J. Assoc. Off. Anal. Chem. 74(5), 883-886. 

Organophosphorus pesticides Acephate , Azinphos-methyl , Chlorpyrifos , Chlorpyriphos-methyl , Diazinon , Dichlorvos (DDVP), Dicrotophos , Dimethoate , Disulfoton , Ethoprop , Eenamiphos , Eenitrothion , Fenthion , Fosthiazate , Malathion , Methamidophos , Methidathion , Methyl-parathion , Mevinphos , Naled , Oxydemeton-methyl , Para-thion , Phorate , Phosalone , Phosmet , Pirimiphos-methyl , Profenofos , Terbufos , Tetrachlorvinphos , Trichlorfon . 

Garcia-Rmz, C. et al.. Enantiomeric separation of organophosphorus pesticides by capillary electrophoresis. Application to the determination of malathion in water samples after preconcentration by off-line solid-phase extraction. Anal. Chim. Acta, 543, 77, 2005. 

The reagent sequence is specific for endosulfan and phosphamidon. Other insecticides, e.g. organochlorine insecticides, such as endrin, aldrin, dieldrin, DDT and BHC, organophosphorus insecticides, such as malathion, parathion, dimethoate, quinalphos, phorate and fenitrothion, or carbamate insecticides, such as baygon, car-baryl and carbofuran do not react. Neither is there interference from amino acids, peptides or proteins which might be extracted from the biological material together with the pesticides. 

Pesticides are also a major source of concern as water and soil pollutants. Because of their stability and persistence, the most hazardous pesticides are the organochlorine compounds such as DDT, aldrin, dieldrin, and chlordane. Persistent pesticides can accumulate in food chains for example, shrimp and fish can concentrate some pesticides as much as 1000- to 10,000-fold. This bioaccumulation has been well documented with the pesticide DDT, which is now banned in many parts of the world. In contrast to the persistent insecticides, the organophosphorus (OP) pesticides, such as malathion, and the carbamates, such as carbaryl, are short-lived and generally persist for only a few weeks to a few months. Thus these compounds do not usually present as serious a problem as the earlier insecticides. Herbicides, because of the large quantity used, are also of concern as potential toxic pollutants. Pesticides are discussed in more detail in Chapter 5. 

Various committees set up by the UK Society for Analytical Chemistry have carried out very detailed studies on the application of GC with flame photometric detection to methanol extracts of grain for the determination of malathion and dichlorvos [ 134] and organophosphorus in pesticides [135]. 

Gas chromatography has been used [183] to determine the following at organophosphorus insecticides at the microgram per litre level in water and waste water samples Azinphos-methyl, Demeton-O, Demeton-S, Diazinon, Disulfoton, Malathion, Parathion-methyl and Parathion-ethyl. This method is claimed to offer several analytical alternatives, dependent on the analyst s assessment of the nature and extent of interferences and the complexity of the pesticide mixtures found. Specifically, the procedure uses a mixture of 15% v/v methylene chloride in hexane to extract... 

The report by Haas and Guardia (18) pertains to their efforts to apply immunological methods for the assay of pesticide residues, and expresses their aim to test the suitability of methods for field analytical purposes. Haas and Guardia also used DDT and malathion to represent two of the most important classes of insecticides, chlorinated hydrocarbons and organophosphorus compounds. They first attempted to prepare insecticide-protein antigens in which enzymes were used as the protein carrier. Antiserum of rabbits injected with DDA-carbonic anhydrase or malathion-chymotrypsin failed to show the presence of the respective antibodies. 

Pesticides are another class of chemicals capable of damaging the nervous system and, even at low levels, produce deficits detectable by psychological testing. The organophosphorus insecticides, which are chemical relatives of the most potent nerve gases, are notorious poisons and, carelessly handled, as often happens in underdeveloped countries, can prove lethal. Parathion, diazinon, and malathion are representatives of this class and are widely used in the United States. Acute poisoning episodes produce signs such as eye irritation, headache, dizziness, nausea, and visual... 

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