Quantification and Chemical Identification of NOx Reduction Agent AdBlue (AUS32) Using ATR-FTIR

Importance of the Topic

AdBlue (AUS32) is essential for reducing NOx emissions in diesel vehicles through selective catalytic reduction. Ensuring its quality and composition according to ISO 22241 standards is critical for environmental compliance, engine performance, and regulatory adherence.

Objectives and Study Overview

This study evaluates the Agilent Cary 630 FTIR spectrometer with a diamond ATR module to both identify and quantify urea concentration in commercial AdBlue. The aim is to develop a rapid, cost-effective FTIR-based method compliant with ISO 22241-2 for routine quality control.

Methodology and Instrumentation Used

The analysis uses the Agilent Cary 630 FTIR spectrometer equipped with a single-reflection diamond ATR module. The Agilent MicroLab software guided workflow facilitates both qualitative identification and quantitative analysis. Identification follows a spectral library match (HQI scoring), while quantification uses the MicroLab Quant application to build a linear calibration curve from urea standards (10–60% w/w). Key FTIR parameters: 4000–650 cm−1 range, 4 cm−1 resolution, 256 scans per spectrum.

Main Results and Discussion

The FTIR method achieved reliable identification of AdBlue with high Hit Quality Index values (>0.99) and clear differentiation from non-urea samples. Quantification yielded excellent linearity (R = 0.99934) and precision (standard deviation < 0.3% for 32.5% w/w urea). Independent validation with control samples showed total standard errors around 0.2%. Analysis of commercial samples demonstrated >99% accuracy and repeatability with minimal sample preparation.

Benefits and Practical Applications

The developed FTIR-ATR method offers:

• Rapid analysis (~2.5 minutes per sample for 256 scans, faster at lower scans).
• Minimal sample volume and preparation.
• Elimination of reagents and complex equipment.
• Automated software guidance reduces operator error and training requirements.
• Compliance with ISO 22241-2 identification requirements and extended quantification range beyond traditional methods.

Future Trends and Potential Uses

As environmental regulations tighten and demand for AdBlue grows, compact FTIR-ATR systems will likely become standard in production and quality control labs. Integration of advanced chemometric models could further enhance sensitivity and broaden analyte scope. Field-portable FTIR devices may enable on-site monitoring and rapid compliance checks.

Conclusion

The Agilent Cary 630 FTIR-ATR platform coupled with MicroLab software provides a robust, efficient, and economical solution for AdBlue quality assurance. Its rapid identification and quantification capabilities align with ISO standards, reducing cost and complexity in routine analysis.

References

1. Foerter, D. C.; Whiteman, C. S. Typical Installation Timelines for NOx Emissions Control Technologies on Industrial Sources. Institute of Clean Air Companies, 2006.
2. Fojtikova, P. et al. Tracking AdBlue Properties During Tests of Selective Catalytic Reduction (SCR) Systems: Suitability of Various Analytical Methods for Urea Content Determination. Int. J. Energy Res., 2020, 44, 2549–2559.