Quantitation of natural triacylglycerols by reversed-phase liquid chromatography with direct liquid inlet mass spectrometry

Myher, J. J.; Kuksis, A.; Marai, L.; Manganaro, F.

doi:10.1016/s0021-9673(00)96264-2

Cited by 60 publications

(21 citation statements)

References 18 publications

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“…As expected from the fatty acid composition (Table 5), the TAGs are almost entirely composed of palmitic, oleic and linoleic acids. The TAGs identified correspond extremely well with previous literature, 5,23,24 with several previously unreported TAGs eluting at longer retention times, as well as eight DAG species.…”

Section: Survey Of Vegetable Oilssupporting

confidence: 88%

“…These ranged from highly unsaturated compounds such as LnLnL, to more saturated palmitic acid containing TAGs, such as POP, and they were all seen in the current study. Marai et al 23 and Myher et al 24 identified similar numbers of compounds using direct liquid inlet mass spectrometry and gave an indication of the relative proportions of the various molecular species. Studies with light-scattering detectors, especially the work of Palmer and Palmer 3 identified some of the components seen eluting at longer retention times.…”

Section: Interpretation Of Apci Mass Spectra Of Tagsmentioning

confidence: 94%

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Identification of triacylglycerol positional isomers present in vegetable oils by high performance liquid chromatography/atmospheric pressure chemical ionization mass spectrometry

Mottram

Woodbury

Evershed

1997

Rapid Commun. Mass Spectrom.

186

123

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Non-aqueous reversed-phase high performance liquid chromatography (HPLC) has become an established means of separating the triacylglycerols (TAGs) present in natural fats and oils.1 The most efficient separations have been achieved with columns packed with chemically bonded octadecylsilyl phases, employing mobile phases consisting of acetonitrile with acetone, propionitrile or chlorinated solvents. Separation is based on both the combined chain length of the fatty acyl residues and on the total number of double bonds in the molecule. A range of detection methods, including evaporative light scattering, 2,3 refractive index [4][5][6] and flame ionization detection 7 have been employed in the analysis of TAGs. However, identification of components using these methods relies on relative retention times or collection of peaks followed by mass spectrometric analysis. With very complex mixtures such as milk fat or fish oils, identification of TAGs in this way becomes impractical. Consequently mass spectrometric detection, which provides detailed information on the molecular weight and fatty acid composition of TAG molecular species, as well as allowing identification of partially resolved or co-eluting peaks, is becoming increasingly widespread.Whilst + , which allow identification of the fatty acids present in each TAG species. 9 The technique has been applied to the analysis of several vegetable oils. [10][11][12] In addition to determining which fatty acids are present in a TAG, it is also important to be able to determine their positions on the glycerol backbone of the molecule since this has considerable biochemical and nutritional significance.13,14 The ability to unambiguously identify positional isomers of individual components of TAG mixtures, is a long standing problem in lipid chemistry. One method for stereospecific analysis of TAGs involves using enzymatic hydrolysis to sequentially cleave the fatty acids at sn-1 and sn-2. These are then analysed directly and the most probable fatty acid at sn-3 calculated. 15 Christie et al. 16 have developed a method in which TAGs are partially hydrolysed and derivatized to diacylglycerol urethanes which can be analysed by gas chromatography. Both of these methods, however, are time consuming. In enzymatic hydrolysis there may be some selectivity for certain chain lengths and numbers of double bonds, as well as a possibility of acyl migration during the analysis. Similarly, urethane derivatization is not suitable for the analysis of more complex fats and oils. Argentation HPLC, using a silver-ion impregnated column in conjunction with polar solvents, has been demonstrated to separate ABA and AAB type positional isomers, where A and B represent different fatty acyl moieties, 17 but gives no information on the positions of fatty acids in an ABC type TAG. A recent paper described the analysis of a number of γ-linolenic-acid-containing vegetable oils using silver-ion HPLC in conjunction with APCI mass spectrometry. 18 We recently showed that positional isomers of TAGs can be...

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Section: Survey Of Vegetable Oilssupporting

confidence: 88%

Section: Interpretation Of Apci Mass Spectra Of Tagsmentioning

confidence: 94%

Identification of triacylglycerol positional isomers present in vegetable oils by high performance liquid chromatography/atmospheric pressure chemical ionization mass spectrometry

Mottram

Woodbury

Evershed

1997

Rapid Commun. Mass Spectrom.

186

123

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“…They suggested that acyl groups in the sn-1 and 3 positions should oxidise faster than those in the sn-2 position. Vegetable oils are composed of many molecular species of triglycerides, esterified with various saturated and/or unsaturated fatty acids in the sn-1, 2 and 3 positions of glycerols (Myher et al 1984;Wada et al 1985). Although linoleic acid is highly concentrated in the sn-2 position among the three sample triglycerides, both linoleic and linolenic acids in rapeseed oil are predominantly distributed in the sn-2 position (Brockerhoff and Yurkowski 1966), while linolenic acid in soya bean oil is distributed randomly among the individual positions (Kuwayama and Usui 1974).…”

Section: Resultsmentioning

confidence: 99%

Influence of fatty acids of different unsaturation in the oxidation of purified vegetable oils during microwave irradiation

Yoshida

1993

J Sci Food Agric

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Purified vegetable oils (soya bean, safflower and rapeseed) containing stearic, oleic, linoleic or linolenic acid at different levels (05-100 g kg-I), were exposed to microwave irradiation for several periods of time to study the contribution of fatty acids of different unsaturation to the oxidative stability of these oils. The evaluation of the oils was based on peroxide value or carbonyl and anisidine values as an indicator for the primary or secondary oxidation products, respectively. A pro-oxidative effect of the added fatty acids was established. The extent of this effect depended on the degree of unsaturation of added fatty acids and/or purified vegetable oils. During microwave treatment the oxidative rate of purified vegetable oils was rapid in the presence of the unsaturated fatty acids, but comparatively lower for the corresponding saturated fatty acid or hydrocarbon. The oxidative state of the oils was lower in the rapeseed oil than in the soya bean oil or safflower oil. In assessing the propensity to oxidation particular attention should be paid to not only the type of free fatty acids, but also the difference of glyceride structure in the purified vegetable oils.

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“…EI-MS allowed differentiation between FA esterified in the sn-1 (3) and sn-2 positions, on the basis of the observation of the [M -RCOOCH 2 ] +˙ formed by cleavage of the FA esterified in the sn-1(3)-position only (14). The abundance of the [M -RCOO] + ion cleaved from the sn-1(3)-position was four times that cleaved from sn-2 position in LC-CI-MS (15). In the collision-induced dissociation (CID) spectra produced by negative ion chemical ionization (NICI), the [M-H-RCOO-100] − ions were observed to be formed primarily by loss of FA from the sn-1(3)-positions (16)(17)(18)(19)(20).…”

mentioning

confidence: 96%

“…Myher et al (15) quantified separated TAG species of vegetable oils in direct inlet RP-LC-MS using response factors calculated from the ratio of the area percentage of total ion current and calculated TAG composition. Kallio was used for the determination of calibration curves obtained with mixtures of AAB-and ABA-type TAG standards.…”

mentioning

confidence: 99%

Regiospecific determination of short‐chain triacylglycerols in butterfat by normal‐phase HPLC with on‐line electrospray‐tandem mass spectrometry

Kalo

Kemppinen

Ollilainen

et al. 2004

Lipids

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This study uses normal-phase HPLC with on-line positive ion electrospray mass spectrometry (ESI-MS) to obtain quantitative compositional data on both synthetic and butterfat short-chain TAG. The product ion tandem MS of standards averaged 11.1 times lower in abundance of the ion formed by cleavage of FA from the sn-2-position for the pairs of regioisomers in the TAG classes: L/L/S-L/S/L and L/S/S-S/L/S, where L denotes long and S short acyl chain (C2-C6). The molar correction factors, determined for 42 regioisomeric pairs of short-chain TAG of 20 randomized mixture of standards, differed by 1.4-80% as the ratios varied between 0.217 and 5.847. Butterfat TAG were resolved into four fractions on short flash chromatography grade silica gel columns. Pairs of regioisomers in the TAG classes L/S/S-S/L/S with predominance of L/S/S isomers and the sole regioisomers in the TAG classes L/L(M)/S were identified by tandem MS, where M denotes either 8:0 or 10:0 acyl chain. The total proportion of L/L(M)/S isomers was estimated at 34.7 and that of L/S/S-S/L/S at 1.0 mol%, including a small proportion of S/S/S. In contrast to previous work, the present data indicate the presence of a small proportion of butyric and caproic acids in the sn-1-position. The overall distribution of the FA in the short-chain TAG of butterfat, calculated from direct MS measurements, was consistent with the results of indirect determinations based on stereospecific analyses of total butterfat.

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Quantitation of natural triacylglycerols by reversed-phase liquid chromatography with direct liquid inlet mass spectrometry

Cited by 60 publications

References 18 publications

Identification of triacylglycerol positional isomers present in vegetable oils by high performance liquid chromatography/atmospheric pressure chemical ionization mass spectrometry

Identification of triacylglycerol positional isomers present in vegetable oils by high performance liquid chromatography/atmospheric pressure chemical ionization mass spectrometry

Influence of fatty acids of different unsaturation in the oxidation of purified vegetable oils during microwave irradiation

Regiospecific determination of short‐chain triacylglycerols in butterfat by normal‐phase HPLC with on‐line electrospray‐tandem mass spectrometry

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