Quantitative determination of primary aromatic amines in recycled cold-cure and flexible foams

Importance of the Topic

Modern recycling of polyurethane based cold cure and flexible foams requires strict control of carcinogenic primary aromatic amines to protect human health and comply with regulatory standards. Among these, 2 4 diaminotoluene (TDA) and 4 4 diamino diphenylmethane (DAPM) are critical targets due to their carcinogenic and mutagenic potential. Ensuring their concentration remains below the OEKO TEX Standard 100 limit of 20 mg per kilogram is essential before reusing recycled foam materials.

Objectives and Study Overview

This study describes the development and validation of a high performance liquid chromatography method for the quantitative determination of TDA and DAPM in recycled cold cure and flexible foams derived from discarded mattresses. The goal was to achieve high sensitivity, robustness and minimal sample preparation for reliable routine analysis.

Methodology and Sample Preparation

A step gradient HPLC method was established using water and acetonitrile mobile phases each modified with 0.1 percent triethylamine at a flow rate of 1.0 milliliter per minute. The column temperature was maintained at 25 degrees Celsius with detection at 290 nanometers. Calibration curves were generated for both analytes over five concentration levels, and spiking experiments were performed on foam extracts to assess accuracy and recovery.

Used Instrumentation

• AZURA P 6.1L LPG pump (up to 700 bar)
• Autosampler 3950 with full loop injection
• AZURA CT 2.1 column thermostat
• AZURA MWD 2.1L multi wavelength detector with 10 millimeter flow cell
• ProntoSIL 120 3 C8 ace EPS column (150 by 4.6 millimeters)

Main Results and Discussion

The method demonstrated excellent linearity with correlation coefficients (R2) of 0.999 for both TDA and DAPM. Limits of detection were determined at 0.63 micrograms per milliliter for TDA and 0.67 micrograms per milliliter for DAPM. Chromatographic overlays of spiked and unspiked samples confirmed accurate quantification in the complex foam matrix without interference.

Benefits and Practical Applications

• Rapid and reproducible quantification of carcinogenic aryl amines
• Minimal sample preparation reduces analysis time
• High sensitivity suitable for regulatory compliance testing
• Robust performance with recycled foam matrices

Future Trends and Potential Uses

Integration of mass spectrometric detection could further enhance selectivity and sensitivity. Automation of sample handling and online monitoring of foam recycling streams are promising developments. Expansion of the method to additional aromatic amines and other recycled polymer matrices will support broader quality control applications.

Conclusion

The presented HPLC method using the AZURA Analytical HPLC Plus system provides a fast, reliable and sensitive approach for monitoring carcinogenic primary aromatic amines in recycled cold cure and flexible foams. It meets industry requirements for throughput and regulatory compliance while maintaining robust performance in demanding matrices.

References

• OEKO TEX Standard 100 limit values for aromatic amines designation 20 mg per kilogram