Analysis of Aromatic Amines Derived From Banned Azo Dyes in Textiles by CE-MS/MS

Importance of the topic

Aromatic amines released by the reduction of banned azo dyes pose significant health risks, including carcinogenic effects. Stringent regulations in the EU and other jurisdictions limit their concentration in consumer textiles to ensure chemical safety and protect public health.

Objectives and Study Overview

This study aimed to establish a rapid, sensitive method for quantifying three target aromatic amines (4,4'-oxydianiline, 4,4'-diaminodiphenylmethane, and 4-chloro-2-methylaniline) in fabric samples. The approach combined a modified QuEChERS extraction with capillary electrophoresis coupled to tandem mass spectrometry (CE-MS/MS).

Methodology

The workflow involved:

• Sample preparation by a high-pH QuEChERS protocol (1 g fabric, acetonitrile/NaOH) and cleanup via MgSO₄/NaCl partitioning.
• Filtration of supernatant, dilution with background electrolyte (0.5 M acetic acid, pH 2.5), and direct injection.
• Electrophoretic separation at 28 kV in a PVA-coated capillary (50 µm id, 60 cm length) to suppress EOF and minimize peak tailing.
• MRM detection on an ESI-positive Agilent 6430 MS, monitoring two transitions per analyte for quantitation and confirmation.

Used Instrumentation

• Agilent 7100 Capillary Electrophoresis system
• Agilent 6430 Triple Quadrupole Mass Spectrometer
• PVA-coated silica capillaries (50 µm id, total length 60 cm)

Main Results and Discussion

The method demonstrated:

• Linear response over 10–1,000 ppb (R² > 0.997) with LODs between 0.5 and 0.9 ppb.
• Precision with run-to-run RSDs of 0.8–5.8 %.
• Recoveries ranging from 92 to 123 % for spiked levels (10, 20, 50 ppb).
• Analysis time under 6 minutes per sample.
• Detected residues in textile samples well below the 30 ppm regulatory limit; the highest observed level was 25.2 ppb.

Benefits and Practical Applications

This CE-MS/MS protocol offers:

• Rapid throughput and minimal solvent and sample consumption.
• High sensitivity suitable for regulatory compliance testing.
• Reduced matrix effects and peak tailing via PVA capillary coating.
• Flexibility to extend to additional aromatic amines.

Future Trends and Potential Uses

Emerging directions include:

• Integration with automated high-throughput platforms for large-scale screening.
• Development of novel capillary coatings and microfluidic CE devices to enhance resolution.
• Coupling with high-resolution mass spectrometry for broader target screening.
• Application of machine-learning algorithms for advanced data analysis and pattern recognition.

Conclusion

The combination of QuEChERS extraction with CE-MS/MS provides a robust, efficient, and sensitive approach for monitoring banned aromatic amines in textiles. It meets regulatory requirements and supports routine quality control in the textile industry.

Reference

1. Ahlström L-H, Eskilsson CS, Björklund E. Determination of banned azo dyes in consumer goods. Trends Anal Chem. 2005;24:49–56.
2. Pinheiro HM, Touraud E, Thomas O. Aromatic amines from azo dye reduction: status review with emphasis on direct UV spectrophotometric detection in textile industry wastewaters. Dyes Pigments. 2004;61:121–39.
3. Directive 2002/61/EC. Council Directive 76/769/EEC, amendment on restricted azo colorants. 2002.
4. FDA Guidance for Industry: Color Additive Petitions – Chemical and Technological Data. 2017.
5. Huang M, Fu R. Analysis of EU banned azo colorants in textiles using Poroshell 120 and 1290 Infinity. Agilent Technologies Application Note; 2011.
6. Dall’Anese RG, Bartolini G, Franchi A. Quantitative determination of aromatic amines from banned azo dyes in textiles using LC–MS/MS. Agilent Technologies Application Note; 2014.