Direct determination of oleic acid in soybean oil by capacitively coupled contactless conductivity detection capillary electrophoresis in an oil-miscible KOH/1-propanol/methanol medium

• Autor(a) principal: Böckel,Wolmir José
• Data de Publicação: 2014
• Outros Autores: Silva,Yara Patrícia da, Mendonça,Carla R. B., Simó-Alfonso,Ernesto F., Ramis-Ramos,Guillermo, Piatnicki,Clarisse M. S.
• 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=S0103-50532014000900016
• topic: oleic acid; non-aqueous capillary electrophoresis (NACE); contactless capacitively coupled contactless conductivity detection (C4D); soybean oil

The aim of this work was to develop a quick direct analytical technique for the determination of oleic acid content in soybean oil by non-aqueous capillary electrophoresis with capacitively coupled contactless conductivity detection. The oil-miscible background electrolyte was a mixture of methanol/1-propanol (1:6 v/v) containing 4 × 10-2 mol L-1 KOH and 10% (v/v) ethylene glycol. Samples of 50 g L-1 soybean oil were prepared directly in the background electrolyte added with 1.33 × 10-3 g L-1 of salicylic acid as internal standard. Quantitative tests were performed by adding to the samples pure oleic acid in the range from 0.53 to 2.13 × 10-3 mol L-1. Under negative polarity anionic solutes moved faster than the electro-osmotic flow so that oleic acid was detected in 16 minutes. The limits of detection and quantification were, respectively, 24 and 81 µmol L-1. Such results demonstrate that, unlike required by other methods, low levels of oleic acid can be quantitatively determined in soybean oil without prior extraction.