title: Method development for the analysis of trans-fatty acids in hydrogenated oils by capillary electrophoresis.
abstract: A novel capillary electrophoresis methodology using UV indirect detection (224 nm) for the analysis of trans-fatty acids in hydrogenated oils was proposed. The electrolyte consisted of a pH 7 phosphate buffer at 15 mmol x L(-1) concentration containing 4 mmol.L(-1) sodium dodecylbenzenesulfonate, 10 mmol x L(-1) polyoxyethylene 23 lauryl ether (Brij 35), 2% 1-octanol and 45% acetonitrile. Under the optimized conditions, ten fatty acids, C12:0, C13:0 (internal standard), C14:0, C16:0, C18:0, C18:1c, C18:1t, C18:2cc, C18:2tt and C18:3ccc were baseline-separated in less than 12 min. The proposed methodology was applied to monitor the formation of trans-fatty acids during hydrogenation of Brazilnut oil. A crude oil sample (42.1% linoleic acid, 37.3% oleic acid, 13.4% palmitic acid, and 7.0% stearic acid) was mixed with 0.25% of a nickel-based catalyst and submitted to two independent hydrogenation conditions: 175 degrees C, 3 atm, 545 rpm for 60 min (GH(1) sample), and 150 degrees C, 1 atm, 545 rpm for 30 min (GH(2) sample). For the most severe hydrogenation condition (higher temperature and pressure, under longer reactional period), a more complete conversion of linoleic and oleic acids into stearic acid occurred with concomitant formation of the trans-species, elaidic acid (C18:1t). For the milder hydrogenation procedure that generated sample GH(2), larger amounts of linoleic and oleic acids remained, in addition to the transformations already observed in the GH(1) sample.
authors.affiliation: Instituto de Química, Universidade de São Paulo, São Paulo, SP, Brazil.
authors.forename: Marcone A L
authors.initials: MA
authors.lastname: de Oliveira
authors.forename: Victor E S
authors.initials: VE
authors.lastname: Solis
authors.forename: Luiz A
authors.initials: LA
authors.lastname: Gioielli
authors.forename: Bronislaw
authors.initials: B
authors.lastname: Polakiewicz
authors.forename: Marina F M
authors.initials: MF
authors.lastname: Tavares
mesh_terms: D019075:Electrophoresis, Capillary / Q000379:methods*; D009821:Oils / Q000737:chemistry*; D044242:Trans Fatty Acids / Q000032:analysis*
chemical_list: D009821:Oils; D044242:Trans Fatty Acids