Miscellaneous herbicides

Smith and Fitzpatrick [24] have also described a thin layer method for the detection in water and soil of herbicides residues, including Atrazine, Barban, Diuron, Linuron, Monouron, Simazine, Trifluralin, Bromoxynil, Dalapon, Dicamba, MCPB, Mecoprop, Dicloram, 2,4r-D, 2,4-DB, Dichlor-prop, 2,4,5-T and 2,3,6-trichlorobenzoic acid. 

Neutral and basic herbicides were extracted from water made alkaline with sodium hydroxide or from soil, with chloroform extracts of soil were cleaned up on a basic alumina containing 15% of water. Acidic herbicides were extracted with ethyl ether from water acidified with hydrochloric acid or from an aqueous extract of soil prepared by treatment with 10% aqueous potassium chloride that was 0.05m in sodium hydroxide and filtration into 4m hydrochloric acid. The concentrated chloroform solution of neutral and basic herbicides was applied to a pre-coated silica gel plate containing a fluorescent indicator and a chromatogram was developed two-dimensionally with hexane-acetone (10 3) followed after drying by chloroform-nitromethane (1 1). The spots were detected in ultraviolet radiation. Atrazine, Barban, Diuron, Linuron, Monouron, Simazine and Trifluralin were successfully separated and were located as purple spots on a green fluorescent backgroimd. The ether extracts were dried over sodium sulphate. 

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Table 4.10. Methods for the determination of miscellaneous herbicides (from author s own files)...

Miscellaneous herbicides Liquid chromatography-mass spectrometry [484-486]... 

Miscellaneous herbicides High-performance liquid chromatography [487]... 

Tweedy BG, Houseworth LK. 1976. Miscellaneous herbicides. In Kearney PC, Kaufman DD, eds. Herbicides, chemistry, degradation, and mode of action, Vol. 1 and 2. New York, NY Marcel Dekker, 815- 833. 

Substituted phenols Chlorophenoxy compounds Substituted acetic and propionic acids Amides and thioamides Substituted ureas Carbamates and dithiocarbamates Symmetrical triazines Benzoic acid derivatives Miscellaneous herbicides... 

Benzoic acids Chlorinated benzenes Miscellaneous herbicides... 

Table 6 MISCELLANEOUS HERBICIDES SCREENED FOR NITROSAMINE CONTAMINATION OTHER PESTICIDES SCREENED FOR NITROSAMINE CONTAMINATION (40)...

Helling et al. (1971), also working with a Chlorella (C. sorokiniana), detected the movement of 11 triazine herbicides, nine phenylureas, and 13 other miscellaneous herbicides, together with two methylcarbamate insecticides, in a thin layer of soil supported on a chromatography plate. The Chlorella suspension was aspirated onto the soil-covered plate, which was then incubated at 100% relative humidity zones of pesticide movement were visible within 24 to 48 hr by algal inhibition. The authors foimd this procedure to be adaptable to detection of movement of many other herbicides and some insecticides and fungicides. 

Table 5.2 shows examples of the major NDPE herbicides, and Figure 5.8 shows examples of other classes of miscellaneous herbicides whose mode of action has been considered identical to that of NDPEs based on their similar symptomology. The typical symptoms of these compounds are similar to those of paraquat. They cause a light-dependent, rapid chlorosis and necrosis due to a rapid induction of peroxidative degradation of cellular constituents, particularly membrane lipids. Several ultrastructural studies have revealed that the NDPEs and other compounds (oxadiazon, LS 82-556, M B 39279) show distinct differences in the sequence of ultra-structural damage compared to that induced by paraquat. ... 

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