15N-labeled glyphosate synthesis and its practical effectiveness

Abstract

Glyphosate is the herbicide with the greatest participation in the world market, and it has been used intensively in agriculture for over 30 years, especially because of its relatively low cost and high effectiveness on different species. This study describes a synthesis method of glyphosate in the form of the isopropylamine salt enriched in the stable nitrogen isotope ( 15 N). The 15 N-herbicide synthesis was performed using a phosphomethylation reaction with dialkyl phosphite and 15 N-glycine. The tests were conducted at a microscale and equimolar quantities. A 20% yield was obtained at the established conditions. To test the effectiveness of the synthesized glyphosate, an experiment was performed in a growth chamber with the weed Lolium multiflorum (ryegrass), which is mentioned to be effectively controlled as indicated in package inserts ofisopropylamine salt-based products (glyphosate). The experimental design was completely randomized, with four replicates, and treatments consisted of isopropylamine salt sources at the commercial dose recommended for the product (720 g a.i. ha -1 ). The production of green and dry phytomass of the above-ground part and roots was evaluated 21 days after application (DAA), and the treatment toxicity was evaluated 7, 14, and 21 DAA. The isopropylamine salt sources did not differ, recognizing them as useful isotopic tracers. Key words: Lolium multiflorum, isopropylamine salt, stable isotope Síntese do glifosato marcado com nitrogênio-15 e sua eficiência prática RESUMO: O glifosato é o herbicida de maior participação no mercado mundial, sendo utilizado intensivamente na agricultura há mais de 30 anos, principalmente devido ao custo relativamente baixo e à alta eficiência sobre diferentes espécies. Descreve-se um método para a síntese do glifosato na forma do sal isopropilamina enriquecido no isótopo estável do nitrogênio ( 15 N). A síntese do herbicida-15 N foi realizada utilizando-se da reação de fosfometilação com diaquil fosfito e glicina-15 N. Os testes foram realizados em microescala e em quantidades equimolares. Foi possível obter um rendimento de 20%. Para testar a eficiência do glifosato sintetizado, realizou-se experimento em câmara de crescimento com a planta daninha Lolium multiflorum (azevém), a qual é eficazmente controlada segundo à bula dos produtos a base do sal de isopropilamina (glifosato). O delineamento experimental foi inteiramente casualizado, com quatro repetições, sendo os tratamentos provenientes de fontes de sal de isopropilamina na dose comercial recomendada do produto (720 g i.a. ha -1 ). Avaliou-se a produção de fitomassa fresca e seca, da parte aérea e radicular, aos 21 dias após a aplicação (DAA), e a toxicidade dos tratamentos aos 7, 14 e 21 DAA. As fontes de sal de isopropilamina empregados não diferiram, o que deverá permitir sua utilização como traçador isotópico. Palavras-chave: Lolium multiflorum, sal de isopropilamina, isótopo estável

Isotopic Fingerprinting for the Authenticity Control of Crop Protection Active Compounds using the Representative Insecticide Fipronil

“…However, isotopic fingerprinting is more and more used to assess the origin and fate of organic compounds in the environment 29 or to evaluate the effectiveness of synthesis processes. 30 For this reason, compound-specific isotopic fingerprinting was evaluated for its potential in the authenticity control of active compounds used in crop protection products. As an exemplary active, the insecticide Fipronil, which is widely used all over the world in different applications, was chosen.…”

“…As the production of pharmaceutical active ingredients is closely related to the production of crop protection active compounds, it is almost remarkable that information on isotopic fingerprinting of crop protection active compounds, especially in the context of authenticity control, is scarce in the literature. However, isotopic fingerprinting is more and more used to assess the origin and fate of organic compounds in the environment or to evaluate the effectiveness of synthesis processes …”