Atrazine structure

The product-ion spectra of the (M - - H)+ ions of atrazine, the structure of which is shown in Figure 3.29, and three of its transformation products showed that if the isopropyl side-chain was present in the structure a constaut neutral... 

Figure 3.29 Structure of atrazine. Reprinted from J. Chromatogr., A, 915, Steen, R. J. C. A., Bobeldijk, I. and Brinkman, U. A. Th., Screening for transformation products of pesticides using tandem mass spectrometric scan modes , 129-137, Copyright (2001), with permission from Elsevier Science.

Ureides (e.g., diuron, linuron) and triazines (e.g., atrazine, simazine, ametryne) all act as inhibitors of photosynthesis and are applied to soil (see Figure 14.1 for structures). They are toxic to seedling weeds, which they can absorb from the soil. Some of them (e.g., simazine) have very low water solubility and, consequently, are persistent and relatively immobile in soil (see Chapter 4, Section 4.3, which also mentions the question of depth selection when these soil-acting herbicides are used for selective weed control). 

Du Preez, L.H., Solomon, K.R., and Carr, J. A. et al. (2005). Population structure of the African Clawed Frog (Xenopus laevis) in maize-growing areas with atrazine application versus non-maize-growing areas in South Africa. African Journal of Herpetology 54, 61-68. 

Structurally related compounds may cross-react with the antibody, yielding inaccurate results. In screening for the herbicide alachlor in well water by immunoassay, a number of false positives were reported when compared with gas chromatography (GC) analysis. A metabolite of alachlor was found to be present in the samples and it was subsequently determined that the cross-reactivity by this metabolite accounted for the false-positive results. On the other hand, cross-reactivity by certain structural analogs may not be an issue. For example, in an assay for the herbicide atrazine, cross-reactivity by propazine is 196% because of atrazine and propazine field use... 

Figure 17. Structure affinity relationship measurement using reflectometric interference spectroscopy of atrazine versus an antibody in water. A variety of derivatives of triazines are measured at a number of concentrations to obtain affinity constants.

Kulikova N, Perminova I (2002) Binding of atrazine to humic substances from soil, peat, and coal related to their structure. Environ Sci Technol 36 3720-3724... 

Laird DA, Barriuso E, Dowdy RH, Koskinen WC (1992) Adsorption of atrazine on smectites. Soil Sci Soc Am J 56 62-67 Laird DA, Fleming PD (1999) Mechanisms for adsorption of organic bases on hydrated smectite surfaces. Environ Toxicol Chem 18 1668-1672 Lambert SM (1967) Functional relationship between sorption in soil and chemical structure. J Agric Food Chem 15 572-576 Lambert SM (1968) Omega, a useful index of soil sorption equilibria. J Agric Food Chem 16 340-343... 

Algal densities and biomass reduced, diversity decreased, and species composition altered. Within 16 days after removal of atrazine stress, net productivity was indistinguishable from controls, but community structure remained altered at day 21 (Hamala and Kollig 1985)... 

Dewey, S.L. 1986. Effects of the herbicide atrazine on aquatic insect community structure and emergence. Ecology 67 148-162. 

Hapeman, C J., S. Bilboulian, B.G. Anderson, and A. Torrents. 1998. Structural influences of low-molecular weight dissolved organic carbon mimics on the photolytic fate of atrazine. Environ. Toxicol. Chem. 17 975-981. 

Several hundred-pesticide compounds of diverse chemical structures are widely used in the United States and Europe for agricultural and non-agricultural purposes (Fig. 10). Some are substitutes for organochlorines, which were banned due to their toxicity, persistence, and bioaccumulation in environmental matrices. According to a report published by the US-EPA, a total of 500,000 tons of pesticides was used in 1985 [144, 145, 148]. As far as specific pesticides are concerned, worldwide consumption of Malathion and Atrazine in 1980 amounted to 24,000 and 90,000 tons, respectively [149,150]. In the Mediterranean countries, 2100 tons of Malathion (active ingredient) were sprayed during the same period compared to 9700 tons in Asia [150]. 

Figure 1. The metabolic pathway of atrazine in sorghum. The major pathway is indicated by bold arrows, the dashed arrows indicate minor pathways, and the dotted arrows indicate hypothesized reactions. The structure in brackets was not identified...

The top 20 agrochemicals in terms of sales dollars are compiled in Tables 11.6 and 11.7. The list shows both modern products requiring small dosages and old ones with high dosages. The former products require much smaller application rates, but also have much higher unit prices. The most expen-sive agrochemicals in terms of unit prices are the modern insecticides -cyhalothrin ( 768/kg) and Imidacloprid ( 461/kg) the cheapest ones are the old herbicides Atrazin ( 4.90/kg) and 2.4-D ( 5.80/kg). As shown in Table 11.8, the cheaper products are the simpler ones in terms of their chemical structure. 

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