Quantitative Analysis of Solutions Using a High Resolution Portable Raman Spectrometer

Importance of the Topic

Raman spectroscopy offers high‐resolution molecular identification and the unique ability to analyze aqueous samples noninvasively. Its portability enables point‐of‐use measurements, making it an attractive tool for rapid quantitative analysis in industrial, research, and quality control environments.

Study Objectives and Overview

This study aimed to develop and validate a quantitative calibration model for simultaneous determination of glucose, fructose, and sucrose concentrations in aqueous mixtures. Using a portable high‐resolution Raman spectrometer coupled with multivariate chemometric software, the work demonstrates feasibility of on‐site sugar analysis in tertiary solutions.

Applied Instrumentation

• i-Raman Plus portable Raman spectrometer with 785 nm laser (~300 mW)
• Fiber‐optic probe for through‐glass vial sampling
• BWIQ multivariate analysis software (PLS regression, PCA, airPLS, SVM)

Methodology

Thirty‐one standard solutions (0.4 M total sugar) were prepared following a designed calibration scheme. Raman spectra (176–3200 cm⁻¹) were acquired with 50 s integration time. Duplicate measurements yielded 62 spectra: 50 for calibration and 12 as an independent prediction set. No spectral preprocessing was applied. A Partial Least Squares (PLS1) regression model was built over the 250–1500 cm⁻¹ range for each sugar component.

Main Results and Discussion

The three‐factor PLS models achieved excellent performance for all sugars. For glucose, measured vs. predicted plots showed R²>0.999, with RMSEC and RMSEP below 0.008 M. Similar statistics were obtained for fructose and sucrose. Independent validation samples confirmed the model’s predictive accuracy, demonstrating robust quantification across varying mixture compositions.

Benefits and Practical Applications

• Rapid, non‐destructive quantification of multiple sugars in aqueous matrices
• Portable instrumentation enables field and on‐line monitoring
• Minimal sample preparation and direct measurement through standard vials
• High analytical precision suitable for food, beverage, and bioprocess industries

Future Trends and Potential Applications

Emerging developments may include expanded libraries for other analytes, integration of advanced machine‐learning algorithms for enhanced spectral deconvolution, and deployment in continuous industrial processes. Miniaturization and improved user interfaces will further broaden adoption in quality control, environmental monitoring, and biomedical fields.

Conclusion

The study confirms that a portable high‐resolution Raman spectrometer combined with chemometric modeling can accurately and reliably quantify glucose, fructose, and sucrose in complex aqueous mixtures. This approach offers a versatile solution for rapid field and laboratory analysis.

References

• Pelletier M.J. Applied Spectroscopy 57, 20A–42A (2003)