Direct characterization of commercial lecithins by easy ambient sonic-spray ionization mass spectrometry

Abstract

Commercial lecithins are composed mainly of phospholipids and triacylglycerols. The analysis of the commercial lecithins, including their fraction of phospholipids, normally involves laborious and expensive protocols. Easy ambient sonic-spray ionization mass spectrometry (EASI-MS) is shown to be an efficient technique for the analysis of lipids. Samples of commercial lecithins including standards, refined, deoiled and modified soy lecithin were tested. Characteristic profiles of phosphatidylcholines and triacylglycerols are detected by EASI(+)-MS, whereas EASI(-)-MS provided phosphatidylethanolamines, glycophospholipids and free fatty acids profiles. Acetylated lecithins also displayed characteristic acetylated derivatives. EASI-MS data was also compared to MALDI-MS, and found to display richer compositional information. The industrial process applied to lecithin fabrication was also characterised via typical EASI-MS profiles. EASI-MS both in its positive and negative ion modes offers a direct, fast and efficient technique able to characterise commercial lecithin.

Desorption/ionization efficiencies of triacylglycerols and phospholipids via EASI‐MS

“…In contrast, EASI(+)‐MS, as Fig. illustrates, is able to detect both TAG and PC ions in a lipid mixture, even when they have quite similar desorption/ionization efficiencies . Experiments were carried out to compare the EASI(+) desorption/ionization efficiencies of TAG and PC.…”

“…EASI has been one of the most used ambient techniques for PL and TAG analysis. [29][30][31]27,32] EASI is based on sonic-spray ionization, [33,34] which creates very small droplets of solvent (e.g., methanol) that become charged (both positively and negatively) because of the statistically unbalanced distribution of cations and anions in the droplets, which have limited charge-carrying capacity. The dense stream of sonic bipolar charged droplets is then used to pick up analytes from the surface.…”

In situ analysis of soybeans and nuts by probe electrospray ionization mass spectrometry

“…Compared to those techniques, PESI‐MS requires lower sample volume, shorter time analysis and minimal sample preparation . Recently, easy ambient sonic‐spray ionization (EASI) has been employed for direct analysis of vegetable oils, phospholipids present in lecithins and brazil nut oil . No sample preparation or pre‐separation was needed for EASI application …”

“…[25] No sample preparation or pre-separation was needed for EASI application. [22][23][24][25] Lipid oxidation in foods constitutes a complex chain of reactions that yields to primary products (peroxides, hydroperoxides), which, once exposed to extended oxidation conditions, gives rise to secondary oxidation products, including aldehydes, ketones, epoxides and hydroxy compounds. Most of these secondary oxidation products produce undesirable sensation (i.e.…”

Alleviation of ion suppression effect in sonic spray ionization with induced alternating current voltage

“…SSI has been characterized by generating charged droplets through sonic speed nebulizing gas coaxial to spray capillary instead of high voltage. Although application of SSI to detection of various real samples, such as amino acids, proteins, brain tissue, commercial lecithins, and wood typification of endangered trees, has been reported in recent years, little effort has been put to improve its analytical performance. Especially, the ion suppression effect, which occurs in most cases, might seriously limit the further application of SSI in complex sample analysis.…”