Comparison of Separations of Fatty Acids from Fish Products Using a 30‐m Supelcowax‐10 and a 100‐m SP‐2560 Column

Abstract

Commercial fish oils and foods containing fish may contain trans and/or isomerized fatty acids (FA) produced during processing or as part of prepared foods. The current American Oil Chemists' Society (AOCS) official method for marine oils (method Ce 1i-07) is based on separation by use of poly(ethylene glycol) (PEG) columns, for example Supelcowax-10 or equivalent, which do not resolve most unsaturated FA geometric isomers. Highly polar 100-m cyanopropyl siloxane (CPS) columns, for example SP-2560 and CP Sil 88 are recommended for separation of geometric FA isomers. Complementary separations were achieved by use of two different elution temperature programs with the same CPS column. This study is the first direct comparison of the separations achieved by use of 30-m Supelcowax-10 and 100-m SP-2560 columns for fatty acid methyl esters (FAME) prepared from the same fish oil and fish muscle sample. To simplify the identification of the FA in these fish samples, FA were fractionated on the basis of the number and type of double bonds by silver-ion solid-phase extraction (Ag⁺-SPE) before GC analysis. The results showed that a combination of the three GC separations was necessary to resolve and identify most of the unsaturated FA, FA isomers, and other components of fish products, for example phytanic and phytenic acids. Equivalent chain length (ECL) values of most FAME in fish were calculated from the separations achieved by use of both GC columns; the values obtained were shown to be consistent with previously reported values for the Supelcowax-10 column. ECL values were also calculated for the FA separated on the SP-2560 column. The calculated ECL values were equally valid under isothermal and temperature-programmed elution GC conditions, and were valuable for confirmation of the identity of several unsaturated FAME in the fish samples. When analyzing commercially prepared fish foods, deodorized marine oils, or foods fortified with marine oils it is strongly recommended that quantitative data acquired by use of PEG columns is complemented with data obtained from separations using highly polar CPS columns.

Morphological and Biochemical Profiles of the Gonadal Cycle in the Sea Urchin Paracentrotus lividus: Wild Type vs. Bred

“…Mixtures of fatty acid methyl esters (FAMEs) were analysed using a modified version of the method proposed by Santercole et al [55], using one temperature programme with a 175°C plateau. Each FAME was identified using pure FAME reference materials, a custom reference mixture and Menhaden fish oil analytical standard (Sigma Aldrich, St. Louis, MO, USA).…”

Fatty acid composition of soybean/sunflower mix oil, fish oil and butterfat applying the AOCS Ce 1j-07 method with a modified temperature program

“…The standard GLC 463 has 52 FAMEs, 34 of them being present in the fish oil analyzed (65%). Santercole et al 2012, using direct GLC and fractions obtained with silver ions, quantified the FAMEs in Menhaden oil (MO) and Sparus aurata fish oil using an SP-2560 100 m capillary column. The temperature program takes 110.3 min, practically the same time as the program developed in this work (110 min).…”

Integrated multidimensional and comprehensive 2D GC analysis of fatty acid methyl esters

“…For peak identity in all figures, refer to Table 1. FAME standards as well as using data from previous studies [4,7,23,24].…”