Scanning densitometry and mass spectrometry for HPTLC analysis of lipids: The last 10 years

Abstract

This work is a review on HPTLC contribution to lipid analysis in complex matrices, in the period from 2010 to now, lapse of time where hyphenation with other techniques, especially Mass Spectrometry, has experienced an important growth. Scanning densitometry (SD)-UV/FL of separated lipids, as the core of detection and centerpiece for hyphenation, and its coupling with MS using soft ionization techniques (ESI, APCI, MALDI, DESI and others), are the central axis of this work. The occasional intercalation in this coupling of an on-plate biological assay for effect-direct analysis (EDA) of lipids, as well as the combination of SD with radio-densitometry (RD) using isotopically labeled-lipids are also covered topics. The described techniques make possible to develop strategies for obtaining qualitative and different levels of quantitative information, including untargeted lipids species. HPTLC of lipids has been used for: comparative purposes; fingerprinting; semi-quantitative determination, identification of species; or quantitative determination of a given individual lipid. Goals in molecular biology and biochemistry-related samples have been: preparative isolations; control of purity; verification of metabolic products; on-plate biological assays; profiles in cells; analysis of products from the cellular metabolism; measurement of enzymatic activities; monitoring lipid transport across membranes or at biological interfaces; or monitoring lipid dynamics.

Abbreviations: AcH: acetic acid; AMD: Automated Multiple Development; APCI: Atmospheric Pressure Chemical Ionization; Cer: Ceramides; Chol: Cholesterol; CholE: Cholesteryl esters: CholS: Cholesteryl sulfate; DCM: Dichloromethane; DESI: Desorption Electrospray Ionization; DG: Diacylglycerides; E1: estrone; E2: 17-β estradiol; E3: estriol; EE2: 17-α ethynylestradiol; EDA: Effect-Direct Analysis; ESI: Electrospray Ionization; EtOH: ethanol; FA: Fatty Acids; FAME: Fatty acid-methyl esters; FFA: Free Fatty Acids; GalCer: Galactosyl-Ceramides; Gb₃: Globotriaosylceramides; Gb₄: Globotetraosylceramides; GC: Gas Chromatography; GL: Glyco-lipids; GlcCer: Glucosyl-Ceramides; GSL: Glycosphingolipids; HPTLC: High-Performance Thin-Layer Chromatography; IMS: Ion-Mobility Separation; LacCer: Lactosyl-Ceramides; LC: Liquid Chromatography; LESA: Liquid Extraction Surface Analysis; LPC: Lyso-Phosphatidylcholines; LPG: Lyso-Phosphatidylglycerols; MALDI: Matrix Assisted Laser Desorption Ionization; m.d.: Migration distance; MeOH: Methanol; MG: Monoacylglycerides; NL: Neutral Lipids; PA: Phosphatidic Acids; PC: Phosphatidylcholines; PE: Phosphatidylethanolamines; PG: Phosphatidylglycerols; PI: Phosphatidylinositols; PL: Glycerophospholipids; PMA: Phosphomolybdic acid; PS: Phosphatidylserines; SD: Scanning Densitometry; SL: Sphingolipids; SM: Sphingomyelins; SQ: Semi-quantitative; Sq: squalene; SterylE: Steryl-esters; TG: Triacylglycerides

Graphical Abstract

Keywords:

• Densitometry
• electrospray mass spectrometry
• HPTLC-MS
• lipidomics
• lipids MALDI
• DESI

Acknowledgments

One of us (J.G.) thanks to Spanish Plan Nacional I + D+i (CTQ 2016-76846R project).

Additional information

Funding

This work was supported by DGA-ESF [project 25_20R].