Analysis of in vitro oxidized human LDL phospholipids by solid‐phase extraction and micellar electrokinetic capillary chromatography

Abstract

Phospholipids of in vitro oxidized human low-density lipoproteins (LDL) were separated by two different solid-phase extraction (SPE) methods. One of the two methods was designed to test the effects of gradient elution. This SPE method isolated more phospholipids from in vitro oxidized LDL than the other one according to the results of liquid chromatography and electrospray ionization mass spectrometry (LC ESI-MS) analysis. A micellar electrokinetic capillary chromatography (MEKC) method was also used to analyze phospholipids separated by SPE. The results of MEKC and LC ESI-MS were consistent for the major phospholipid classes, including PC, lysoPC, PE, PI and PS. The MEKC profiles showed significant differences for native and oxidized LDL phospholipids. Therefore, the unique combination of SPE and MEKC methods showed dramatic distinctions between native and in vitro oxidized human LDL phospholipids. The combination also shows great potential for rapid analysis of in vivo oxidized human LDL phospholipids in the future.

The role of lipids in exosome biology and intercellular communication: Function, analytics and applications

“…Advances in mass spectrometry (MS) have made this method the dominating platform in the lipidomic analysis 83 . On its part, nuclear magnetic resonance (NMR) has become a less‐used system limited by its lower sensitivity, the presence of overlapping signals, and the low natural abundance of 13 C for 13 CNMR 84,85 . However, despite limitations, NMR is a powerful analytical method that permits the visualization of single atoms and molecules for lipid identification, with important applications in biomedicine 86‐88 and food science 89‐91 .…”

“…83 On its part, nuclear magnetic resonance (NMR) has become a less-used system limited by its lower sensitivity, the presence of overlapping signals, and the low natural abundance of 13 C for 13 CNMR. 84,85 However, despite limitations, NMR is a powerful analytical method that permits the visualization of single atoms and molecules for lipid identification, with important applications in biomedicine [86][87][88] and food science. [89][90][91] Lipid analysis on MS-based platforms can be classified into three main categories: direct infusion-based "shotgun" analysis, liquid chromatography (LC)-MS systems and gas chromatography (GC)-MS platforms, each one with unique properties.…”

A digest of capillary electrophoretic methods applied to lipid analyzes

“…) . The PLs derived from the oxidation of human low‐density lipoproteins (LDL) with CuSO 4 were also studied using MEKC after a solid‐phase extraction step .…”

Analysis of glycerophospho‐ and sphingolipids by CE

“…The nature of the alcohol modifiers and the proportion used in the separation media have large influence on the separation since they are able to modify the buffer viscosity and dielectric constant, having a great impact especially for highly hydrophobic compounds as glycerophospholipids . MEKC with UV detection has also been employed in glycerophospholipids analysis using low wavelength (200–234 nm) with the aim of determining the glycerophospholipid composition in different samples as soybean and rapeseed lecithins , human high‐density lipoproteins , or native and in vitro oxidized low‐density lipoproteins . However, some problems with the lyso forms detection caused by the lack of one fatty acid and their corresponding possible double bonds limited the usefulness of these strategies.…”

“…MEKC with UV detection has also been employed in glycerophospholipids analysis using low wavelength (200–234 nm) with the aim of determining the glycerophospholipid composition in different samples as soybean and rapeseed lecithins , human high‐density lipoproteins , or native and in vitro oxidized low‐density lipoproteins . However, some problems with the lyso forms detection caused by the lack of one fatty acid and their corresponding possible double bonds limited the usefulness of these strategies.…”