Characterization of the TAG of peanut oil by electrospray LC‐MS‐MS

Abstract

A study of processed peanut oil was undertaken to assess the utility of HPLC combined with tandem MS to obtain data easily regarding the number of TAG of fats and oils and their FA composition. Mass chromatograms and spectra corresponding to only TAG of a single M.W. were obtained for the full range of TAG in the sample. Analysis of the mass spectra allowed the identification of more than 160 TAG in the sample by their FA composition. In addition, it was possible to estimate relative abundances of the TAG and suggest the position of the FA on glycerol for a limited number of cases. This technique greatly simplifies the task of assigning FA to coeluting TAG and facilitates identification of TAG present in trace quantities in mixtures, with possible application in circumstances where such trace TAG could be significant markers. Results are quickly obtained without extensive sample preparation or prefractionation of the sample.Paper no. J10065 in JAOCS 79, 749-753 (August 2002).Separation and identification of components of the complex mixtures of TAG that constitute fats and oils is a challenging analytical chemistry problem. Various approaches to separation by HPLC have been studied over the years (1). MS, and in particular combined HPLC and MS, has substantially improved the analysis of these mixtures (2). Relatively little has been reported concerning the use of electrospray ionization (ESI) MS, ESI-LC-MS, and tandem MS (MS-MS) in the analysis of TAG mixtures. Duffin et al. (3) first reported ESI-MS-MS analysis of TAG (as ammonium or sodium ion adducts) by infusing a solution of the analytes in nonpolar solvents. Studies leading to complete structures of individual TAG by ESI or fast atom bombardment MS-MS on tandem magnetic sector instruments were undertaken by Cheng et al. (4). Hsu and Turk (5) described the use of ESI-MS-MS in a triple quadrupole instrument for the structural elucidation of lithium ion adducts of individual TAG. Marzilli and coworkers (6) studied the selectivity of FA loss from sn-1,3 vs. sn-2 positions in a small set of TAG under MS-MS and MS 3 conditions in an ion trap mass spectrometer.In a preliminary study for this paper, the FA composition of TAG components of cocoa butter was studied by ESI-MS-MS (7).Peanut oil was chosen as a test substance for the ability of LC-MS-MS to identify TAG components because it contains a wider range of FA (from at least C 16 to C 26 ) than is typical for vegetable oils. Previous reports on the characterization of peanut oil have involved combinations of analytical methods. Myher et al. (8) analyzed natural and randomized peanut oils by HPLC coupled to direct inlet chemical ionization MS, identifying 35 TAG molecular species in a randomized sample and 16 TAG molecular species in natural samples. Sempore and Bezard (9) collected fractions from isocratic HPLC with refractive index detection, analyzed the FA of the fractions as methyl esters by GLC, and deduced the composition of the peanut oil TAG based on parameters derived from retention time data and mathe...

Fatty acid composition of commercial vegetable oils from the French market analysed using a long highly polar column

“…The present results are comparable to some previously reported data (Sanders, 2002;Dorschel, 2002), but SFA and LA contents in the tested groundnut oil mixture are slightly lower and OA content is slightly higher than the average values calculated by Dubois et al, 2007 from literature data. The ALA content of groundnut oil measured in the present study (0.1%) is lower than the published results for US oils (0.7%) (Dubois et al, 2007;Dorschel, 2002), but similar to findings for Greek oils (0.1%) (Christopoulou et al, 2004). The specificity of groundnut oil of containing long chain (C > 20) FAs,i.e.,20:0,20:1,22:0, and 24:0, is thus confirmed.…”

A comparative study of the composition of triacylglycerol molecular species in equine and human milks

“…More than three fatty acids were detected in the same chromatographic peak (Table 1) indicating that TAGs had co-eluted. This was not surprising as it has previously been documented (Dorschel 2002;Mottram and Evershed 2001) that components with the same ECN value, known as "critical pairs", are linked to problems in their separation by HPLC. Additionally, co-elution probably occurred as long chain saturated components caused the effective ECN to be increased as previously reported (Dorschel 2002;Mottram and Evershed 2001).…”

Peanut oil: Compositional data

“…More than 160 TAG were identified in peanut oil by HPLC-tandem MS [38] most of them being di-and triunsaturated (POO, SOO, PLO, OOO, OLO, LLO, and LLL). Natural peanut oils possess markedly non-random enantiomeric structures of highly asymmetric positional placement of the long-chain saturated fatty acids [5,7,18,34,36].…”