Multifaceted Spectrophotometric Analysis of Vitamins and Vitamin-like Substances

Significance of the Topic

Accurate characterization of vitamins and vitamin-like substances is critical for food safety, nutritional studies and pharmaceutical quality control. Spectroscopic techniques offer rapid, non-destructive and versatile methods to probe optical properties and molecular signatures of these compounds.

Objectives and Study Overview

This application summary describes combined use of ultraviolet-visible (UV–Vis) spectrophotometry, spectrofluorophotometry, Fourier transform infrared (FTIR) spectroscopy and Raman microscopy to evaluate absorption, fluorescence and vibrational spectra of a range of vitamins and vitamin-like substances.

Methodology

Sample Preparation and Measurement Conditions
Samples of vitamins A, B1, B2, B6, B12, C, D, E, K and vitamin-like compounds such as biotin, folic acid, p-aminobenzoic acid, anthranilic acid, lipoic acid and rutin were dissolved or suspended in appropriate solvents to achieve absorbance below 1.0 AU or suitable concentration for fluorescence. UV–Vis spectra were recorded from 200 to 800 nm with solvent-specific ranges. Fluorescence measurements used excitation wavelengths based on UV absorbance peaks and emission scans at 1.0 nm intervals. FTIR measurements employed attenuated total reflection with diamond ATR crystal, 4 cm−1 resolution and 40 scans. Raman spectra were acquired with 532 and 785 nm excitations, 10 scans and 5 s exposure per scan at ×100 magnification.

Used Instrumentation

• UV–2600i Plus UV–Visible Spectrophotometer
• RF–6000 Spectrofluorophotometer
• IRSpirit-TX FTIR Spectrophotometer with QATR-S diamond ATR
• AIRsight Infrared Raman Microscope (IRTracer-100)

Main Results and Discussion

UV–Vis spectra revealed characteristic absorption maxima for each vitamin and related substance, enabling peak assignment in the UV region. Fluorescence analysis showed strong emission for vitamins A, B2, B6, E and some vitamin-like compounds, though signals for vitamin A near 490 nm and vitamin K at 270 nm were unstable likely due to photobleaching. FTIR and Raman spectra provided clear vibrational fingerprints, facilitating qualitative identification via spectral libraries. Fluorescent samples occasionally increased baseline in Raman spectra, requiring careful interpretation.

Benefits and Practical Applications

The integrated spectrophotometric approach allows simultaneous qualitative and quantitative analysis of multiple vitamins and analogues in diverse matrices. UV–Vis offers rapid concentration measurement, fluorescence enhances sensitivity for trace components, and FTIR/Raman deliver robust compound identification without extensive sample preparation.

Future Trends and Potential Applications

Advances in miniaturized spectrometers and in-line process monitoring will expand real-time nutrient analysis in food and pharmaceutical production. Coupling spectral libraries with machine learning can improve automated identification and quantitation of vitamins in complex formulations.

Conclusion

This multifaceted spectrophotometric protocol provides a comprehensive toolkit for analysis of vitamins and vitamin-like substances, combining UV–Vis, fluorescence, FTIR and Raman methods to deliver detailed optical and molecular information with minimal sample handling.

References

• Analytical Solutions for Food Development (Shimadzu Application News)
• Difference in Quantifiable Concentration Ranges of UV–Vis and Fluorescence Spectrophotometers, Application News No. A615