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Table 6 Comparison of several analytical methods, reaction types observed and species detected during oxidation of linseed oil

From: Low temperature oxidation of linseed oil: a review

Method Variables measured or reactions observed Chemical species detected Location of peaks References
FTIR Hydroxyl group formation Hydroxyl group 3430 cm-1 (Lazzari & Chiantore1999)
  Double bond decreasing in abundance Cis double bond 3011, 1654, 722 cm-1 (Lazzari & Chiantore1999)
  The cis- trans isomerisation reaction and changes of conjugation Trans conjugated double bond 987, 971 cm-1 (Oyman et al.2005a; Mallégol et al.2000)
  The broadening of carbonyl peak Carbonyl compounds 1747 cm-1 (Lazzari & Chiantore1999)
H-NMR Decreasing the abundance of cis double bonds Non-conjugated cis double bonds 5.4 ppm (Oyman et al.2005a; Miccichè et al.2006)
  Decreasing the abundance of double allylic hydrogen Double allylic hydrogen 2.7 ppm (Oyman et al.2007)
  The changes in conjugation Conjugated double bond 5.5-6.6 ppm (Oyman et al.2005a; Miccichè et al.2006)
  Formation of conjugated hydroperoxides Conjugated ethyl linoleate hydroperoxide 7.9 and 8 ppm (Miccichè et al.2006)
  Isomerisation of cis double bonds Allylic methane 4.3 ppm (Miccichè et al.2006)
  Disappearance of vinylic hydrogen Vinylic hydrogens 5.3 ppm (Martini et al.2009)
  Epoxidation reaction Epoxy groups 2.9-3.1 ppm (Martini et al.2009)
Raman Changes of double bond abundance Non-conjugated cis double bond 1265, 1655 cm-1 (Oyman et al.2005a)
  Changes of conjugation structure Conjugated double bond 1599, 1634 cm-1 (Oyman et al.2005a)
  Oxirane group formation Trans-9,10- and cis-9,10-epoxystearic acids 1064, 1295, 1443 cm-1 (Muik et al.2005)
  Carbonyl formation Saturated aldehydes 1725 cm-1 (Muik et al.2005)
   Conjugated unsaturated aldehydes 1690 cm-1  
UV–vis Formation of ligand complex of cobalt catalyst Co(II) octoate solution in toluene 590 nm (Tanase et al.2004)
  Hydroperoxide formation Conjugated diene 232-232.5 nm (Belhaj et al.2010; Hendriks et al.1979)
Chemiluminescence Hydroperoxides formation Hydroperoxides   (Rolewski et al.2009)
Oxygen uptake Oxygen consumption    (Oyman et al.2005a)
DSC-TGA Thermal decomposition reactions    (Lazzari & Chiantore1999)
  Reaction exotherm profiles    (Tuman et al.1996)
HPLC Identification and quantitation of aldehyde emissions Aldehydes compounds such as ethanal, propanal, pentanal, hexanal.   (Fjällström et al.2002)
GC-MS Fatty acid composition Fatty acid methyl esters Retention times depend on the columns and methods (García-Martínez et al.2009)
MALDI-RTOF-MS and ESI-MS Triacylglycerol composition Triacylglycerols Based on mass-to-charge ratio (m/z) (Krist et al.2006)
SPME-GC-MS Identification and quantitation of VOC Saturated and unsaturated hydrocarbons Retention times depend on the columns and methods (Krist et al.2006; Jeleń et al.2000; García-Martínez et al.2009; Lee et al. 105; Lee & Min2010)
   Aldehydes, ketones, carboxylic acids, alcohols, furans   
   Aromatic compounds   
SEC Polymerisation (cross-linking) reaction Hydroperoxides Retention time varies (Lazzari & Chiantore1999; Miccichè et al.2006)
   Dimeric fraction   
   Higher oligomer   
EPR/ESR (discussed later in this paper) Radical formation Allylic, pentadienyl, peroxyl, hydroxyl, alkoxyl radicals   (Zhu & Sevilla1989; Dikalov & Mason2001)
   Metal-dioxygen complexes   (Yamada et al.1984)