Obtenção e análise de espectros de absorção de luz por herbicidas
Carregando...
Data
2018-12-18
Autores
Dadazio, Tais Santo
Título da Revista
ISSN da Revista
Título de Volume
Editor
Universidade Estadual Paulista (Unesp)
Resumo
Cada substância apresenta um padrão de resposta específico quando submetidas à radiação solar. No entanto, estudos que comparam diferentes moléculas, a fim de identificarem padrões de comportamento são escassos. Portanto, estudos que relacionam o padrão de absorbância com a radiação solar disponível, buscando estimar o potencial de fotodegradação de defensivos, são inexistentes na literatura. Nesse contexto, esse trabalho estudou a absorção de luz por diferentes herbicidas e metabólitos com o objetivo de prever a sensibilidade desses compostos à fotólise em condições de campo e a necessidade de utilizar manejos ou tecnologias que possam reduzir a degradação por efeito da luz. Foram investigadas 36 substâncias, correspondendo a herbicidas e seus metabólitos. Cada solução foi analisada por meio de varredura das absorbâncias das substâncias na faixa de 185 a 900nm (Ultravioleta (UV)/ Visível (VIS)/Infra vermelho(IF)). Posteriormente, o potencial de cada comprimento de onda em promover a fotólise de um composto específico foi determinado multiplicando-se a disponibilidade de luz no espectro solar padrão e a absorbância observada na solução padronizada desse composto no mesmo comprimento de onda. De acordo com os resultados, cada substância apresentou faixas de comprimento de ondas com maior potencial de absorção, especialmente na região do VIS e com outros estudos permitirão avaliar quais compostos podem ser utilizados para protegê-las. Assim, foi possível agrupar as substancias em relação ao índice de fotodegradação em ordem decrescente na faixa de radiação do UVA, UVB e UVC. Os herbicidas pendimenthalin e trifluralin se destacam por absorverem expressivamente luz visível (400 a 700 nm).
Each substance has a specific response pattern when subjected to solar radiation. However, studier comparing differente molecules in order do identify behavior patterns are scarce. Therefore, studies that relate the absorbance pattern to the available solar radiation, seeking to estimate the photodegradation potential of pesticides are not available in the literature. In this context, this work studied the absorption of light by different herbicides and metabolites in order to predict the sensitivity of these compounds to photolysis underf field conditions and the need to use care or technologies that can reduce light degradation. There were investigated 36 substances, corresponding to herbicides and thei metabolites. Each solution was analyzed by scanning the absorbances of substances in the range of 185 to 900 nm (UV/VIS/IF). Subsequently, the potential of each wavelength promoting the photolysis of a specific compound was determined by multiplying the light availability in the standard solar spectrum and the observed absorbance in the standard solution of that compound at the same wavelenght. According to the results, each substance showed wavelenght ranges with greater absorption potential, and with other studier, it will be possible to evaluate which compounds can be used to protect them. Thus, it was possible to group the substances in relation to the photodegradation index in descending order in the UVA, UVB and UVC radiation range. The herbicides pendimenthalin and trifluralin stand out by expressively absorbing visible light (400 to 700 nm).
Each substance has a specific response pattern when subjected to solar radiation. However, studier comparing differente molecules in order do identify behavior patterns are scarce. Therefore, studies that relate the absorbance pattern to the available solar radiation, seeking to estimate the photodegradation potential of pesticides are not available in the literature. In this context, this work studied the absorption of light by different herbicides and metabolites in order to predict the sensitivity of these compounds to photolysis underf field conditions and the need to use care or technologies that can reduce light degradation. There were investigated 36 substances, corresponding to herbicides and thei metabolites. Each solution was analyzed by scanning the absorbances of substances in the range of 185 to 900 nm (UV/VIS/IF). Subsequently, the potential of each wavelength promoting the photolysis of a specific compound was determined by multiplying the light availability in the standard solar spectrum and the observed absorbance in the standard solution of that compound at the same wavelenght. According to the results, each substance showed wavelenght ranges with greater absorption potential, and with other studier, it will be possible to evaluate which compounds can be used to protect them. Thus, it was possible to group the substances in relation to the photodegradation index in descending order in the UVA, UVB and UVC radiation range. The herbicides pendimenthalin and trifluralin stand out by expressively absorbing visible light (400 to 700 nm).
Descrição
Palavras-chave
Absorbância., Fotodegradação., Fotoproteção., UVA., UVB.