Achieving Uniformity in Multivariate Data Analysis for Raman Spectroscopy

Raman spectroscopy is useful in a wide variety of fields and applications.

In a review published last year in Applied Spectroscopy, researchers reviewed new techniques and developments in multivariate data analysis (MVDA) for Raman spectroscopic data (1). MVDA is most frequently used for more complex spectral data including time series or line profiles, and Raman 2D and 3D imaging maps.

“Even though there are some existing standards for creation, implementation, and validation of methods and models employed in industry and academics, further research and development in the field must contribute to their improvement,” the researchers wrote in the study.

Raw data is rarely used in Raman spectroscopy and instead, spectra are correlated or manipulated. Calibration models can be used to characterize samples, but it’s necessary to regularly validate instruments to ensure it does not alter predictions. This is especially important to keep in mind when analyzing pharmaceutical products.

“A model transfer may be required for different reasons, such as replacement or significant repair of the instrumentation,” the scientists wrote. “Modeling can also be used to consistently harmonize Raman spectroscopic data across several instrumental designs, accounting for variations in the resulting spectrum induced by different components.”

The pretreatment step is very important, the scientists wrote, as it is necessary to accurately calibrate an instrument to create a common ground when starting an experiment.

Ideally, scientists could create an open access database to ensure there is harmonization of new Raman instruments using an accepted protocol, the researchers wrote.

“There already exists a large array of methods that can be used to harmonize Raman spectroscopic data, and more are being created by a very active chemometric community,” they wrote. “Thus, it can be expected that a complete chemometric method tailored to build a robust and reliable system for Raman harmonization can be soon developed and should be adopted by the Raman community.”

Reference

Barton, B.; Thomson, J.; Diz, E. L.; Portela, R. Chemometrics for Raman Spectroscopy Harmonization. Applied Spectroscopy.2022, DOI: https://doi.org/10.1177/00037028221094070