Determination of total aldehydes in fuel ethanol by MBTH method: sequential injection analysis

• Autor(a) principal: Oliveira,Fabio Santos de
• Data de Publicação: 2005
• Outros Autores: Leite,Bárbara Cecília O., Andrade,Marta Valeria A. Santana de, Korn,Mauro
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Journal of the Brazilian Chemical Society (Online)
• Texto Completo: http://old.scielo.br/scielo.php?script=sci_arttext&pid=S0103-50532005000100013
• topic: sequential injection analysis; total aldehyde determination; MBTH; binary sampling; monosegmentation

A sensitive SIA method was developed for total aldehyde determination in automotive fuel ethanol samples. It was based on the selective reaction of aliphatic aldehydes with 3-methyl-2-benzothiazolone hydrazone (MBTH) with the formation of blue dye in the presence of Fe3+. Monosegmentation and binary sampling were employed to increase the sensitivity of the method. In order accelerate reaction rate of MBTH and aldehyde a mixing coil was inserted into a microwave oven cavity were the sample zone was homogeneously heated. The linear range was 0.3-6 mg L-1 with a precision, expressed as relative standard deviation, lower than 2.5% and detection limit of 60 mug L-1. The method has been successfully applied to the determination of total aldehydes in fuel ethanol and the results agreed with those obtained with 2,4-DNPH-HPLC. In the optimal condition the system can carry out 10 samples per hour.