Lipids

, Volume 47, Issue 3, pp 329–344 | Cite as

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

  • Viviana Santercole
  • Pierluigi Delmonte
  • John K. G. Kramer
Methods

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.

Keywords

Supelcowax-10 SP-2560 GC Fish oil Fish muscle Fatty acid determination Silver-ion SPE columns Equivalent chain length (ECL) 

Abbreviations

CLA

Conjugated linoleic acid

CPS

Cyanopropyl siloxane

DHA

Docosahexaenoic acid

ECL

Equivalent chain length

EPA

Eicosapentaenoic acid

FA

Fatty acid

FAME

Fatty acid methyl ester

FT-NIR

Fourier transform near infrared

GC

Gas chromatography

LC

Long-chain

MUFA

Monounsaturated fatty acid

NMI

Non-methylene interrupted

PEG

Poly(ethylene glycol)

pha

Phytanic acid

phe

Phytenic acid

PUFA

Polyunsaturated fatty acid

SPE

Solid-phase extraction

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Copyright information

© AOCS 2012

Authors and Affiliations

  • Viviana Santercole
    • 1
  • Pierluigi Delmonte
    • 3
  • John K. G. Kramer
    • 2
  1. 1.Porto Conte Ricerche SrlSanta Maria La PalmaItaly
  2. 2.Agriculture and Agri-Food CanadaGuelph Food Research CenterGuelphCanada
  3. 3.US Food and Drug AdministrationCollege ParkUSA

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