Gota suspensa para avaliação de aldeído total no ar interno e externo do ambiente
AUTOR(ES)
Pereira, Elisabete A., Cardoso, Arnaldo A., Dasgupta, Parnendu K.
FONTE
Química Nova
DATA DE PUBLICAÇÃO
2001-08
RESUMO
A sensitive and simple system was proposed for the in situ measurement of total aldehyde in outdoor or indoor ambient. The method is based on the use of a reagent drop as an useful interface to preconcentrate the sample prior to determination of total aldehyde as formaldehyde. The drop is formed at the tip of a cylindrical tube that contains two optical fibers placed on opposite sides and in contact with the reagent solution. One optical fiber carries the red light to the drop form a light emitting diode (LED). The transmitted light is measured by a second optical fiber/photodiode system. The analytical signal is read and converted into absorbance. The reagent solution of 3-methyl-2-benzothiazoline hydrazone (MBTH) forms a blue cation during reaction with formaldehyde that can be measured at 660 nm. Some aspects of kinetics reaction formation of dye were reevaluated. The formaldehyde reacts with MBTH and forms the azine in about 12 min. The oxidation of MBTH by Fe (III) and the formation of dye requires 3 min. The absorbance of the reagent drop is proportional to the sampling time and to the analyte concentration. The absorbance signal increases with increased sample gas flow until a maximum is reached then decreases until it forms a plateau. The proposed method was evaluated using both outdoor and indoor samples, and it was shown to viable provide an accurate measure of total aldehyde.
Documentos Relacionados
- Estudo da contribuição de um sistema de ar condicionado com distribuição de ar pelo piso para a remoção de particulados e dióxido de carbono do ar de um ambiente interno
- Extração de amônio de filtros de amostragem, coleta e determinação pelo método da gota suspensa
- Avaliação do indice de conforto termico para matrizes suinas em gestação segundo as caracteristicas do ambiente interno
- Qualidade do ar interno e saúde em escolas
- Avaliação da força máxima no limite de escoamento do implante cônico interno (3,5mm) comparado aos implantes hexágono externo regular e estreito