Estudo polarografico e amperometrico do formaldeido e do acetaldeido e suas aplicações analiticas

AUTOR(ES)

Maria Jose de Sousa Ferreira da Silva

DATA DE PUBLICAÇÃO

1993

RESUMO

A differential pulse polarographic method was developed for quantitative determination of formaldehyde and acetaldehyde in aqueous solutions. The aldehydes were converted to imines by reaction with primary amines (monoethanolamine (MEA) and Hexamethylenediamine (HMDA)) and the imino group was reduced at the static mercury drop electrode. A 0,10 moI/l litium chloride solution was used as supporting electrolyte. The polarograms were recorded from - 1.10 V to -1.50 V vs Ag/AgCl for formaldehyde derivated and from - 1.30 V to -1.70 V vs Ag/AgCl for acetaldehyde derivated with scan rate of 5 mV/s and 50 mV pulse height. The drop-time was 1 s and the test solution was de-gassed with nitrogen for 2 minutes. The diffusion current obtained was directly proportional to the concentration of formaldehyde in the range from 0.10 mg/ml to 160 mg/ml (correlation coefficient = 0.9993) with MEA and from 0.60 mg/ml to 85 mg/ml (correlation coefficient = 0.9995) with HMDA. These values for acetaldehyde were from 0.08 mg/ml to 40 mg/ml (correlation coefficient = 0.9999) and 0.09 mg/ml to 90 mg/ml (correlation coefficient = 0.9995), respectively. The aldehydes in aqueous solutions were determined with an average relative error of 1.5 % and an average variation coefficient of 0.2 %. The imine compounds did not have to be isolated for analysis. The time required per analysis is approximately 15 minutes. The method was applied to determine acetaldehyde in alcohol and alcoholic beverages with an average recovery of 98.6 % and to determine formaldehyde in milk and shampoo with an average recovery of 100.6 %. Based in the polarographic behaviour of the imines a method was developed for amperometric titration of the aldehydes. The standardized amines were used as titrant. The experimental conditions were the same as used in polarographic method. Aqueous solutions of the aldehydes in the 20 mg/ml to 300 mg/ml concentration range were titrated with an average relative error of 1.5 % for acetaldehyde and 3 % for formaldehyde.

ASSUNTO(S)

polarografia formaldeido

Documentos Relacionados

• Aplicações analiticas do estudo da reação quimiluminescente de luminol
• Espectrometria de massas pentaquadrupolar e suas aplicações analiticas, sinteticas e em medidas termodinamicas
• Estudo teórico do modelo PC-SAFT e suas aplicações
• Modelos de simulação e suas possíveis aplicações no estudo econômico do biodiesel.
• Voltametria de micropartículas imobilizadas: fundamentos e aplicações analíticas