Rapid Assessment of Lipidomics Sample Purity and Quantity Using Fourier-Transform Infrared Spectroscopy.

Area of Science:

• Analytical Chemistry
• Biochemistry
• Spectroscopy

Background:

• Liquid chromatography-mass spectrometry (LC-MS) is popular for lipidomics, but lacks validated methods for lipid extract quality and quantity assessment.
• Fourier-Transform Infrared Spectroscopy (FTIR) has shown potential for pure lipid quantification, but its accuracy in complex lipid samples is uninvestigated.

Purpose of the Study:

• To comprehensively assess the impact of sample matrix on lipid quantification accuracy using Attenuated Total Reflectance (ATR)-FTIR.
• To establish a simple and rapid workflow for lipidomics sample quality and quantity assessment prior to LC-MS analysis.

Main Methods:

• Utilized ATR-FTIR to analyze pure and complex lipids, focusing on CH- and C=O-stretching vibrations.
• Investigated the influence of sample extraction methods and spectral processing on quantification accuracy.
• Developed a Lipid Quality (LiQ) score based on spectral features to identify common contaminants.

Main Results:

• FTIR demonstrated a quantitative range of 40–3000 ng with a limit of detection of 12 ng for lipids.
• Extraction method and baseline subtraction significantly impacted quantification via CH stretching vibrations.
• The developed LiQ score effectively screened sample quality, improving correlation with LC-MS quantification.
• Absolute quantification by FTIR showed an uncertainty of <10% using a lipid standard.

Conclusions:

• A rapid FTIR workflow enables routine lipidomics sample quality and quantity assessment.
• Excluding poor-quality samples identified by the LiQ score enhances the reliability of lipidomics data.
• This method provides accurate total lipid quantification and normalization, improving downstream LC-MS analysis.