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
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.
| Main Authors: | , , , , , |
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| Format: | Digital revista |
| Language: | English |
| Published: |
Sociedade Brasileira de Química
2014
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| Online Access: | http://old.scielo.br/scielo.php?script=sci_arttext&pid=S0103-50532014000900016 |
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