Identification of molecular species of simple lipids by normal phase liquid chromatography–positive electrospray tandem mass spectrometry, and application of developed methods in comprehensive analysis of low erucic acid rapeseed oil lipids

Abstract

Mono-, di-and triacylglycerol (MAG, DAG, TAG), sterol ester (SE), free sterol (S) and free fatty acid (FFA) standards were analyzed in the presence of ammonium ions and ammonia by flow injection MS 2 and MS 3 , and by normal phase-liquid chromatography (NP-LC) MS 2 positive electrospray ionization (ESI) mass spectrometry (MS). The MS data recorded for ammonium adducts ([M + NH 4 ] +) of TAGs, DAGs, and MAGs were consistent with stepwise fragmentation mechanisms. In the first step, ammonium ion in [M + NH 4 ] + donates proton to acylglycerol and ammonia is released. In the second step, FFA is cleaved from protonated TAG, water from protonated 1,3-DAG and MAG, both FFA and water from protonated 1,2-DAG, hence leading to formation of [DAG] + ion from TAG and 1,3-DAG, [DAG] + and [MAG] + ions from 1,2-DAG, and [MAG] + ion from MAG. In the third step, [DAG] + ion of TAG is fragmented to yield [Acyl] + , [Acyl + 74] + , [DAG − 74] + ions, [DAG] ion of 1,3-DAG to [Acyl] + ions, and [MAG] + ion of MAG to protonated FAs, which are decomposed to water and [Acyl] + ions in the fourth step. A stepwise mechanism for fragmentation of FFA was also evident from MS 2 and MS 3 data. Molecular species of low erucic acid rapeseed oil simple lipids were identified from characteristic ions produced in the NP-LC-ESI-MS 2 of [M + NH 4 ] + ions. The percentage composition of the molecular species of each lipid class was calculated from integrated extracted ion chromatograms of [(M + NH 4)] + ions of SE, TAG, MAG, and FFA, of the sum of [(M + NH 4)] + and [(M + NH 4) − NH 3 − H 2 O] + ions of both regioisomers of DAGs, and of sterol fragment ions of S.

Rapid screening of mixed edible oils and gutter oils by matrix-assisted laser desorption/ionization mass spectrometry

“…Development of a reliable and general approach for rapid authentication of edible oils has become highly desirable. 6 Various techniques, including PCR [15], chromatography [16] and chromatography coupled with mass spectrometry (MS) [3,[17][18][19][20][21][22], nuclear magnetic resonance (NMR) [23] and Fourier transform infrared (FT-IR) [24,25], have been developed for analysis of edible oils. As a commonly used analytical tool, MS has been widely applied for analysis of edible oils.…”

Liquid Chromatography–Light Scattering Detector–Mass Spectrometric Analysis of Digested Oxidized Rapeseed Oil

“…Furthermore, normal phase (NP)-HPLC is frequently used in the crude separation of FFA, MAG, DAG, TAG, phospholipids, and different cholesterol species, followed by more detailed gas chromatography (GC) or HPLC analysis. More specialized NP-HPLC-ESI-MS n analysis of different lipid classes has recently been developed [23]. Solid phase extraction (SPE) is often used to separate major lipid classes from each other prior to more specific analysis of different molecular species [22].…”

26 kDa endochitinase from barley seeds: Real-time monitoring of the enzymatic reaction and substrate binding experiments using electrospray ionization mass spectrometry

“…These limitations prompt one to develop sensitive and specific analytical methods for chitinase activity determination without substrate labeling. Mass spectrometry makes such labeling redundant and allows sensitive detection of various molecules as protonated or deprotonated ions or charged salt-adduct ions (Kalo et al, 2006). In previous studies, we reported the mass spectrometric observation of enzymatic activity and reaction time-courses by continuous flow ESI-MS using hen egg white lysozyme (HEWL) (Dennhart and Letzel, 2006) and two types of chitosanases (endo and exo) (Dennhart et al, 2008).…”