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Autofluorescence as a Parameter to Study Pharmaceutical Materials
Published in Victoria Vladimirovna Roshchina, Fluorescence of Living Plant Cells for Phytomedicine Preparations, 2020
Victoria Vladimirovna Roshchina
Among xenobiotics in plant cells, fluorescent pesticides may be found; for example, pesticidal carbamates acting on cholinesterases of both animals and plants (Addison et al. 1977). In addition, carbamates offer the possibility of determining their influence on cholinesterase activity. As early as 1992, Mueller and coworkers presented a list of fluorescent herbicides that could potentially be used in diagnostics. The fluorescence properties of 39 herbicides representing several major types of chemistry were determined. The fluorescence of analytical standards was measured in acetonitrile, acetonitrile + water, and acetonitrile + water + strong acid. Fourteen of the 39 herbicides fluoresced to some extent, and seven (bentazon, chloramben, difenzoquat, fluometuron, imazaquin, 2-methyl-4-chlorophenoxyacetic acid [MCPA], and norflurazon) were identified as good candidates for further method development. Herbicides or their derivatives have been detected with spectrofluorometric methods in various matrices, including fluometuron and its metabolites in soil to 20 ng/g soil, asulam (methyl[(4-aminophenyl)sulfonyl]carbamate) in spinach, and glyphosate ((N-phosphonomethyl) glycine) and its metabolite in natural water. This technique has also been employed to identify other pesticides, such as the methylcarbamates in food, carbaryl (1-naphthyl-N-methylcarbamate) in honeybees or honey, and thiabendazole and carbendazim in various crops. The bipyridiniums fluoresced in acetonitrile very strongly. However, addition of water to the solutions of diquat and paraquat totally quenched the observed fluorescence. Additionally, diquat and paraquat are only very slightly soluble in acetonitrile (but very water soluble), and this would hinder method development. It should be noted that this method has not so far been used for histochemical analysis in plant cells in situ. Only chlorophyll fluorescence is recommended for analysis as a marker for herbicides (Dayan and de Zaccaro 2012).
Toxicity of the herbicides used on herbicide-tolerant crops, and societal consequences of their use in France
Published in Drug and Chemical Toxicology, 2022
Finally, although these herbicides are intended to increase yields by reducing competition from weeds, sometimes yields or benefits may be lower than those obtained without the herbicide with hand weeding. For example, after treating potatoes with sulfosulfuron at a rate of 25 g/ha, total yield was 24 t/ha compared to 29.6 t/ha with hand weeding. Operating profits (difference between selling price and operating costs) amounted to 59,000 Indian rupees per ha compared to 81,000/ha with hand weeding. Increasing the herbicide application rate to 50 or 75 g/ha did not improve yields or benefits (Singh et al. 2017). Lower yields after treatment with the IMIs imazaquin or imazethapyr than with hand weeding have also been observed with soybean (Mills and Witt 1989) and corn (Curran et al. 1992).