000			01909nab a2200205 4500
005			20260520000927.0
008			260224s2011 xxu
245	0	0	_aCharacterization of asphaltenes by nonaqueous capillary electrophoresis
260			_a _b _cene./feb. 2011
270			_a04/04/2011 ; 04/04/2011
300			_a7 p. ; 208-214
520			_aTranscripción del resumen del autor. Nonaqueous capillary electrophoresis was used for the separation and characterization of asphaltene samples from different sources. For the separation medium (background electrolyte), mixtures of tetrahydrofuran and a high-permittivity organic solvent could be used. The best results were obtained with an 80:20 mixture of tetrahydrofuran and acetonitrile, containing 1-10 mM of lithium perchlorate. In this separation medium, asphaltene samples were found to be composed of two fractions that could be clearly separated: one fraction of neutral species and a fraction that carries a positive charge in the solvent mixture employed. Between samples of different origin, differences were found in the relative amounts of the neutral and the charged fractions and in the average electrophoretic mobility of the charged components. Taylor dispersion analysis was applied to estimate the average diffusion coefficient of the asphaltene species in the solvent mixture used. From the results, it is concluded that the asphaltenes are present as nanoaggregate clusters of 3000-4000 Da and that the charged aggregates carry a net charge of approximately +1. The possible correlation between the electrophoretic properties of asphaltenes in crudes of different origin and their field behavior is discussed.
581			_a1
773	0		_tEnergy & fuels _g25
942			_cARTICULO
100	1		_aKok, Wim Th. _945028
100	1		_aGrutters, Mark _945029
100	1		_aShepherd, Andrew G. _942277
999			_c174394 _d174394