Objective:

To identify preservation fluids in sealed biological specimens using spatially offset Raman spectroscopy (SORS) without opening the containers.

Key Findings:

• Successfully identified preservation fluid in 78.5% of cases, with partial agreement in 15%.
• Only 6.5% of samples were misclassified or unclassifiable due to reference library limitations or fluorescence interference.
• The method distinguished visually similar fluids and provided insights into container materials.

Interpretation:

The SORS method allows for noninvasive identification of preservation fluids and container types, enhancing conservation planning and understanding of historical storage practices.

Limitations:

• Classification ambiguities arose from fluorescence effects or secondary components not included in the calibration set.
• Some fluid mixtures were not represented in the reference library.

Conclusion:

The study establishes SORS as a practical tool for heritage science, supporting conservation decisions and monitoring chemical changes in preservation fluids over time.