N-containing pesticides

During the next two years (1976 and 19TT)> registrants of pesticides and EPA laboratories analyzed several hundred samples of N- containing pesticides for N-nitroso contaminant occurrence and concentration. Results of these analyses have been reported elsewhere. What these analyses revealed was what was... 

In recent years greater attention has been given to nitrogen containing pesticides and the possibility of their nitrosation in soil. The N-nitrosamines that form may arise from the parent pesticide or from a pesticide metabolite. The reaction calls for favourable pH conditions (pH 3-4) and excess nitrite. Under field conditions, the nitrosable residues are usually present in traces and only small quantities of these will actually be nitrosated in soils. However, the possibility exists that the small amounts of N-nitrosamines could be assimilated by plants. 

Procedure 12.7 is an example of a basic approach that has also been used to clean up polycyclic aromatic hydrocarbons, polychlorinated biphenyls, and N-, P-, and Cl-containing pesticides before further analysis [25],... 

N- and P-containing pesticides and 507, 614, 619, 622, Liquid extraction, sonication. NPD, ELCD, FPD, Drinking water, waste water. 

Practical aspects. Both detectors have found widespread application in GC for the detection of picogram amounts of N- and P-containing pesticides. 

In a LC-MS study [175] applying FAB besides TSP, APCl, ESI, plasma desorption (PD) ionisation a series of N- and P-containing pesticides were studied. Collision-induced dissociation (CID) spectra were recorded. Pesticide residues could readily be identified, confirmed and quantified. The results for several different polar pesticides were compared with APCI and ESI and were presented [176]. 

N.B. Some alcohols obtained by fermentation could contain pesticides. It is necessary to obtain from the purchaser some guaranty in requiring limit contents (expressed in Parathion e.g.). ... 

Stahkas, C.D. Konidari, C.N. Analytical methods to determine phosphonic and amino acid group-containing pesticides. J. Chromatogr. A, 2001, 907, 1-19. 

The retention and acquisition parameters of common nitrogen- and phosphorus-containing pesticides (phosphoric acid esters, atrazines, etc.) are listed in Table 4.13. It is recommended that the excitation parameters are used initially with equal standard values (0.9 V), which may be slightly adjusted in the case of response optimization. The quality of the product ion spectra is not affected (Figure 4.51). A typical standard run in MS/MS acquisition mode is shown in Figures 4.52 and 4.53. Even at the low 10 pg/pL level, the compounds are detected with high S/N values and full MS/MS product spectra for confirmation (Figure 4.51). 

Miles and Moye [171] have shown that several classes of nitrogen containing pesticides responded to a high performance liquid chromatography post-column reaction detector that employed ultraviolet photolysis with optional reaction with o-phthalicdicarboxaldehyde-2-mercaptoethanol followed by fluorescence detection. It was applied to the determination of N-methylcarbamates, carbamoyl oximes, carbamethoic acids, dithiocarbamates and phenyl ureas, phenyl amides and phenyl carbamates in groimdwater. See also Table 4.3. 

Methyl- and dimethylnaphthalenes are contained in coke-oven tar and in certain petroleum fractions in significant amounts. A typical high temperature coke-oven coal tar, for example, contains ca 3 wt % of combined methyl- and dimethylnaphthalenes (6). In the United States, separation of individual isomers is seldom attempted instead a methylnaphtha1 ene-rich fraction is produced for commercial purposes. Such mixtures are used for solvents for pesticides, sulfur, and various aromatic compounds. They also can be used as low freezing, stable heat-transfer fluids. Mixtures that are rich in monomethyinaphthalene content have been used as dye carriers (qv) for color intensification in the dyeing of synthetic fibers, eg, polyester. They also are used as the feedstock to make naphthalene in dealkylation processes. PhthaUc anhydride also can be made from m ethyl n aph th al en e mixtures by an oxidation process that is similar to that used for naphthalene. 

Extension Toxicology Network, EXTOXNET, 2nd ed., available in hard copy and electronic form from Resource Center, Cornell University, Ithaca, N.Y., 1994. Contains 139 pesticide information profiles (PIPs), 16 toxicology information briefs (TIBS), and other information on current issues in pesticide toxicology and environmental chemistry. 

Lindane is one of eight different hexachlorocyclohexane (HCH), C H Cl, isomers and its Chemical Abstract n.2cniQ is la, 2a 3P, 4a, 5a 6P-hexachlorocyclohexane [58-89-9] (y-HCH or y-BHC, ben2ene hexachloride) (80). Commercial products containing lindane are marketed as either a mixture of isomers or as the pure y-BHC isomer. Not unexpectedly, lindane is a highly stable lipophilic compound and it has been used extensively worldwide as an insecticide. In contrast, hexachloropentadiene, C Cl, is an extremely reactive industrial intermediate used as a chemical intermediate in the synthesis of a broad range of cyclodiene-derived pesticides, which include endosulfan, endrin, heptachlor, and several different organohalogen flame retardants (81). 

Other interesting examples of proteases that exhibit promiscuous behavior are proline dipeptidase from Alteromonas sp. JD6.5, whose original activity is to cleave a dipeptide bond with a prolyl residue at the carboxy terminus [121, 122] and aminopeptidase P (AMPP) from E. coli, which is a prohne-specific peptidase that catalyzes the hydrolysis of N-terminal peptide bonds containing a proline residue [123, 124]. Both enzymes exhibit phosphotriesterase activity. This means that they are capable of catalyzing the reaction that does not exist in nature. It is of particular importance, since they can hydrolyze unnatural substrates - triesters of phosphoric acid and diesters of phosphonic acids - such as organophosphorus pesticides or organophosphoms warfare agents (Scheme 5.25) [125]. 

The persistence of the N-nitrosamine that may be formed in soil will depend on a host of conditions, such as soil type, organic matter content, clay content, pH, the microflora present in the soil, moisture content and temperature, etc. Superimposed on all these factors will be the chemical nature of the pesticide. The N-nitrosoatrazine ( ) formed in soil from the herbicide atrazine ( ) was shown to be rapidly disappeared (1). Thus, in soil W-nitrosoatrazine was observed after one week, but was absent 4 and 10 weeks later (Table IV). In contrast, N-nitroso-butralin (11 ) persisted much longer than N-nitrosoatrazine (9) under the same conditions (Table V) and was still detectable after 6 months (3). Our studies demonstrated that N-nitrosoglyphosate is persistent in the soil. Fox soil treated with 20 ppm of nitrite nitrogen and 740 ppm glyphosate contained about 7 ppm of N-nitrosoglyphosate even after 140 days (6). 

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