Profiling of Unsaturated Lipids by Raman Spectroscopy Directly on Solid-Phase Microextraction Probes

Area of Science:

• Analytical Chemistry
• Spectroscopy
• Biochemistry

Background:

• Lipids are essential biomolecules involved in cellular functions.
• Accurate detection of unsaturated lipids is crucial for various applications.
• Existing methods for lipid analysis can be complex and time-consuming.

Purpose of the Study:

• To develop a novel on-site method for detecting and differentiating unsaturated lipids.
• To evaluate the efficacy of different solid-phase microextraction (SPME) coatings for lipid analysis.
• To establish Raman spectroscopy as a reliable tool for quantifying lipid unsaturation.

Main Methods:

• Direct coupling of SPME probes with Raman spectroscopy.
• Development and testing of polyacrylonitrile (PAN)-embedded SPME coatings (HLB, C8-SCX, C18).
• Optimization of SPME parameters including temperature, time, and washing solvent.

Main Results:

• The C18/PAN coating exhibited minimal background interference for unsaturated lipid analysis.
• Raman band intensity correlated with the number of double bonds in fatty acids.
• Lipid unsaturation was accurately calculated using the ratio of Raman band intensities (1655/1445 cm⁻¹).
• The developed SPME-Raman method demonstrated high activity and detection ability for unsaturated lipids in complex matrices like cod liver oil.

Conclusions:

• The SPME-Raman spectroscopy approach offers a sensitive and specific method for analyzing lipid unsaturation.
• This technology has significant potential for applications in food, environmental, clinical, and biological fields.
• The developed method provides a valuable tool for characterizing oils and other lipid-containing samples.