Alternative methodologies for the determination of aldehydes by capillary electrophoresis

dc.contributor.authorPereira, Elisabete Alves
dc.contributor.authorTavares, Marina Franco Maggi
dc.contributor.authorCardoso, Arnaldo Alves [UNESP]
dc.contributor.institutionUniversidade de São Paulo (USP)
dc.contributor.institutionUniversidade Estadual Paulista (UNESP)
dc.description.abstractThis paper describes 2 alternative methodologies for the determination of selected aldehydes (formaldehyde, acetaldehyde, propionaldehyde, acrolein, and benzaldehyde) by capillary electrophoresis (CE). The first approach is based on the formation of aldehyde-bisulfite adducts and employs free solution CE with reversed electroosmotic flow and indirect detection, using 10 mmol/L 3,5-dinitrobenzoic acid (pH 4.5) containing 0.2 mmol/L cetyltrimethylammonium bromide as the electrolyte. This novel methodology showed a fairly good sensitivity to concentration, with detection limits with respect to a single aldehyde on the order of 10-40 μg/L, a reasonable analysis time (separation was achieved in <8 min), and no need for sample manipulation. A second approach was proposed in which 2,4-dinitrophenylhydrazine derivatives of the aldehydes were detected in a micellar electrolyte medium (20 mmol/L borate buffer containing 50 mmol/L sodium dodecyl sulfate and 15 mmol/L β-cyclodextrin). This latter methodology included a laborious sample preconcentration step and showed much poorer sensitivity (0.5-2 mg/L detection limit, with respect to a single aldehyde), despite the use of sodium chloride to promote sample stacking. Both methodologies proved adequate to evaluate aldehyde levels in vehicular emissions. Samples from the tailpipe exhaust of a passenger car vehicle without a catalytic converter and operated with an ethanol-based fuel were collected and analyzed; the results showed high levels of formaldehyde and acetaldehyde (0.41-6.1 ppm, v/v). The concentrations estimated by the 2 methodologies, which were not in good agreement, suggest the possibility of striking differences in sample collection efficiency, which was not the concern of this work.en
dc.description.affiliationUniversidade de São Paulo Instituto de Química, C.P. 26077, 05599-970, São Paulo, SP
dc.description.affiliationUniversidade Estadual Paulista Instituto de Química, C.P. 355, 14800-910, Araraquara, SP
dc.description.affiliationUnespUniversidade Estadual Paulista Instituto de Química, C.P. 355, 14800-910, Araraquara, SP
dc.identifier.citationJournal of AOAC International, v. 82, n. 6, p. 1562-1570, 1999.
dc.relation.ispartofJournal of AOAC International
dc.titleAlternative methodologies for the determination of aldehydes by capillary electrophoresisen