Simultaneous determination of xanthan gum, optical density, and glucose in aqueous solutions by Vis-NIRS

Significance of Topic

The ability to monitor xanthan gum concentration, optical density and residual glucose in aqueous solutions is critical for industries relying on precise rheological profiles and product consistency. Rapid, simultaneous analysis of these parameters accelerates quality control and reduces operational costs in cosmetic, pharmaceutical and food applications.

Objectives and Overview

This study presents a feasibility evaluation of visible–near-infrared spectroscopy (Vis-NIRS) for the concurrent quantification of xanthan gum, optical density and glucose in aqueous solutions. The aim was to develop robust calibration models that enable sub-minute, preparation-free measurements suitable for routine production monitoring.

Methodology

A set of over 100 customer samples, collected from more than 20 fermenters over four weeks, was split into 75 % for calibration and 25 % for external validation. Spectra were recorded in transmission mode across 400–2500 nm at 40 °C using 4 mm glass vials. Raw data were pretreated with a second derivative filter. Partial Least Squares (PLS) regression was employed for xanthan gum and glucose models, while Multiple Linear Regression (MLR) was used for optical density.

Used Instrumentation

• NIRS XDS RapidLiquid Analyzer (Metrohm)
• 4 mm disposable glass vials
• Vision Air 2.0 Complete software for data acquisition and chemometric modeling

Main Results and Discussion

Glucose model (0–4.5 % w/w): PLS with five latent variables over 626–694 nm and 1662–1744 nm achieved R² = 0.9623 and SEP = 0.34 %.
Xanthan gum model (0–5 % w/w): PLS with four factors in the 1662–1744 nm region showed R² = 0.9431 and SEP = 0.35 %.
Optical density model (0–12 OD units): MLR at 893 nm and 967 nm gave R² = 0.9052 and SEP = 0.90. High coefficients of determination and low prediction errors confirm the method’s reliability for simultaneous multi-component analysis.

Benefits and Practical Applications

The Vis-NIRS approach requires no chemical reagents or extensive sample handling, delivering results in under one minute. This high-throughput method supports inline or at-line quality control, reduces reagent costs and can be operated by non-specialist staff.

Future Trends and Potential Applications

Advancements may include integration of machine learning algorithms for enhanced predictive accuracy, miniaturized fiber-optic probes for real-time process monitoring and extension to other biopolymer systems or complex emulsions.

Conclusion

Vis-NIR spectroscopy coupled with chemometric modeling offers a rapid, cost-effective and user-friendly tool for simultaneous determination of xanthan gum, optical density and glucose in aqueous solutions, enabling efficient quality assurance in industrial settings.

References

• Metrohm AG, NIR Application Note NIR-52: Simultaneous determination of xanthan gum, optical density, and glucose by Vis-NIRS, November 2017.