Determinação dos ácidos eicosapentaenóico, docosahexaenóico e araquidônico em amostras de peixes por eletroforese capilar de zona

Abstract

Eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids, belonging to the omega 3 class, and arachidonic acid (AA), belonging to the omega 6 class, are essential for human health. These fatty acids can be found in abundance in some fish. To contribute to these foods' nutritional assessment and quality control, this work proposes developing an analytical method for determining EPA, DHA, and AA in salmon and sardines by capillary zone electrophoresis with direct UV detection. At first, it was found that AA was below the method's limits of detection and quantification. This led to further analysis of EPA and DHA. The optimized methodology using Box-Behnken 34 design consists of an electrolyte made up of 40 mmol L-1 of TBS (pH 9), 17 mmol L-1 of Brij® 35, 33% v/v of MeOH and 17% v/v of ACN; TSP capillary of 33.5 cm total length (25 cm effective length), 50 µm internal diameter and 375 µm external diameter; hydrodynamic injection of 25 mbar x 5 s; voltage of 27 kV; cartridge temperature of 30 ºC; and detection at 200 nm. The samples were prepared using an alkaline hydrolysis reaction, known as saponification, and the analysis time was less than 15 minutes. The method was validated through some figures of merit such as linearity (r = 0.9752 for EPA and r = 0.9870 for DHA), precision (RSD < 8%), accuracy ((101.01 ± 10.55)% and (91.23 ± 9.58)% for EPA and DHA, respectively, in the salmon samples and (104.30 ± 3.17)% and (93.96 ± 7.05)% in the sardine samples), the limit of detection (0.006 mmol L-1 and 0.003 mmol L-1 for EPA and DHA, respectively, in the salmon samples and 0.005 mmol L-1 and 0.002 mmol L-1 in the sardine samples) and quantification (0.019 mmol L-1 and 0.011 mmol L-1 for EPA and DHA, respectively, in the salmon samples and 0.015 mmol L-1 and 0.007 mmol L-1 in the sardine samples). The fatty acids were quantified by calculating the response factor. In general, the method developed by CE was successful, providing information not only on an academic level but also on a social level about the humanitarian right of access to quality food with high nutritional value.