Fourier transform infrared spectroscopy as a non-destructive method for analysing herbarium specimens

Area of Science:

• Botanical analysis
• Biochemistry
• Spectroscopy

Background:

• Herbarium specimens offer valuable historical data on plant evolution and environmental conditions.
• Analysis of these irreplaceable, delicate samples is often limited, especially with destructive techniques.
• Fourier transform infrared (FTIR) spectroscopy provides a non-destructive method for chemical analysis.

Purpose of the Study:

• To demonstrate the utility of mid-FTIR microspectroscopy for analyzing herbarium specimens.
• To assess the potential for extracting geographical, spatial, and species-specific biochemical variations.
• To evaluate the chemical differences in *Drosera rotundifolia* specimens collected a century apart.

Main Methods:

• Non-destructive mid-FTIR microspectroscopy was applied to *Drosera rotundifolia* herbarium specimens.
• Principal component and hierarchical clustering analyses were used for data interpretation.
• Spectral regions corresponding to lipids and proteins were examined for differentiation.

Main Results:

• FTIR successfully differentiated between three main regions of the plant: lamina, tentacle stalk, and tentacle head.
• Lipids and protein spectral regions were key indicators for distinguishing plant tissues.
• While regional differences were clear, variations between specimens collected 100 years apart were less pronounced.

Conclusions:

• FTIR spectroscopy is a powerful, non-destructive tool for extracting valuable biochemical information from herbarium specimens.
• This method allows for the study of historical plant biochemistry with minimal impact on delicate samples.
• FTIR holds significant potential for unlocking historical ecological and evolutionary data stored in herbaria.