Spectral Imaging of Multivitamins by Confocal Raman Microscopy

ABSTRACT:

Vitamins are becoming increasingly common in over-the-counter health supplements and personal care products. The distribution of the vitamin(s) within the formulation effects their release and stability. Confocal Raman Microscopy (CRM) provides a non-destructive method for mapping the distribution of compounds in a mixture based on their unique Raman spectra. The spectral imaging mode of the CRM will be used to investigate differences in the dispersion of vitamins in an emulsion versus a solid formulation.

EXPERIMENTAL:

Raman spectral imaging was performed on a WITec alpha 300R Confocal Raman Microscope equipped with a 532nm excitation wavelength laser. X, Y and X, Z spectral images were collected at a resolution of 100 pts/line and 100 lines/images.

CONCLUSIONS:

• There is an uneven distribution of the vitamin in the solid formulations, suggesting mechanical mixing.
• The two cream formulations appear to be emulsions with a more even distribution of the vitamin(s).
• Spectral imaging by Confocal Raman Microscopy is a useful tool for investigating the distribution of active ingredients and excipients in over-the-counter vitamin products.