Analysis of Aromatic Amines in Textile Samples

Importance of the topic

The analysis of aromatic amines released from azo dyes in textiles is analytically and regulatory important because many aromatic amines are toxic, some are carcinogenic, and they can be formed or released during dyeing, degradation, or wear. Robust, sensitive analytical methods are needed for screening and quantitation to support compliance with standards (e.g., ISO:14362) and to address environmental and public‑health concerns. Using hydrogen as a carrier gas offers a sustainable alternative to helium while maintaining analytical performance when the GC/MS system and ion source are compatible.

Objectives and study overview

This application note evaluates a hydrogen‑carrier GC/MS workflow for the quantitative determination of 24 target aromatic amines in textile matrices. Key aims were to demonstrate method sensitivity and repeatability, to establish an aqueous calibration range, and to apply the method to real textile samples. The work uses internal standard (anthracene‑d10) calibration and targeted selected‑ion monitoring (SIM) by GC/MS with a hydrogen‑compatible HydroInert ion source.

Methodology

The analytical workflow combined reductive sample treatment, liquid–liquid extraction, and GC/MS analysis with SIM. Main steps:

• Sample: ~0.5 g textile per test.
• Reduction: Samples suspended in 30 mL citrate buffer, heated at 70 °C; 15 mL sodium dithionite added and incubated 30 min to reduce azo bonds and liberate aromatic amines.
• Extraction: Methyl tert‑butyl ether (MTBE) extraction performed; organic extract concentrated to ~2 mL under a gentle nitrogen stream.
• Standards and IS: Stock reference mix (Mix 1, 40 µg/mL) diluted to prepare Mix 2 (4.0 µg/mL). Anthracene‑d10 used as internal standard (10 µg/mL). Seven calibration levels prepared spanning 0.25–20.0 µg/mL.
• Analysis: 2 µL injection (split 10:1) into GC/MS operated in SIM mode; quantifier and qualifier ions were monitored for each compound to ensure selectivity.

Used instrumentation

Instrumentation and critical settings used in the study:

• GC: Agilent 8890 Gas Chromatograph with hydrogen carrier, constant flow 1.0 mL/min.
• Column: Agilent J&W DB‑35ms, 20 m × 0.18 mm, 0.18 µm film.
• Inlet: 290 °C; injection volume 2 µL; split ratio 10:1.
• Oven program: 100 °C (2.0 min) → 135 °C at 15 °C/min (1.0 min) → 240 °C at 45 °C/min (1.0 min) → 290 °C at 15 °C/min (3.0 min).
• MS: Agilent 5977C GC/MSD equipped with the Agilent HydroInert electron ionization source (ion source 250 °C; transfer line 300 °C; quadrupoles 150 °C). Targeted SIM acquisition was employed with compound‑specific quantifier and qualifier ions.

Results and discussion

Calibration and sensitivity:

• An aqueous calibration range of 0.25–20 µg/mL was established for 24 aromatic amines using an internal standard approach.
• The method achieved limits of quantification in textile samples down to 1 µg/g for the target compounds under the described sample preparation and GC/MS conditions.

Precision and chromatographic performance:

• Good chromatographic separation and sensitivity were achieved with hydrogen as carrier gas in combination with the HydroInert source.
• Repeatability was satisfactory: %RSD values were below 5% for 22 of the 24 analytes at 1 µg/mL; two compounds showed higher variability (aniline ~9.2% RSD; o‑toluidine ~5.8% RSD), indicating slightly reduced precision for these species under the tested conditions.

Application to real samples:

• The method was applied to multiple textile samples. Three analytes—aniline, o‑toluidine, and benzidine—were detected in some real samples, confirming the method’s applicability to screening and quantitative analysis of contaminated textiles.
• Observed concentrations in the tested samples included examples on the order of 100s µg/g for o‑toluidine (one measurement ~172 µg/g), ~92 µg/g for aniline in a different sample, and benzidine present at approximately 10–46 µg/g across two samples. These values illustrate that significant residues can be present and that the method detects a broad concentration range.

Benefits and practical applications

The described approach provides several practical advantages:

• Sustainability: Hydrogen carrier gas mitigates helium scarcity concerns while achieving comparable chromatographic resolution when used with hydrogen‑compatible hardware.
• Sensitivity and selectivity: The HydroInert source with SIM acquisition delivered low µg/g LOQs and reliable identification using quantifier/qualifier ions and retention time matching.
• Regulatory relevance: The method’s performance is consistent with requirements for detecting residual aromatic amines relevant to ISO:14362 and other regulatory limits.
• Laboratory adoption: The workflow uses routine GC/MS instrumentation and standard sample handling steps, facilitating integration into QA/QC and research laboratories monitoring textile safety.

Future trends and potential applications

Expected developments and extensions of this analytical approach include:

• Broader analyte panels: Expanding target lists to include additional amines, metabolites, or dye degradation products to provide more comprehensive screening of textile contaminants.
• Automation and higher throughput: Automating extraction and concentration steps (e.g., SPE, robotic liquid handling) to increase sample throughput for routine screening programs.
• Complementary techniques: Combining GC/MS with LC/MS workflows to capture both volatile/semi‑volatile amines and more polar degradation products not amenable to GC.
• Method standardization: Further interlaboratory validation and harmonization to support regulatory adoption and cross‑laboratory comparability, especially when using hydrogen carrier gas.

Conclusion

This application note demonstrates a practical and sensitive GC/MS method for quantifying 24 aromatic amines in textiles using hydrogen as the carrier gas and a HydroInert ion source. The procedure delivered LOQs suitable for regulatory screening (1 µg/g in textile matrices), stable calibration over 0.25–20 µg/mL, and good repeatability for most analytes. The method successfully identified a limited number of problematic amines in real textile samples, supporting its use in compliance testing, product safety checks, and environmental monitoring.

References

1. Nguyen T.L.; Saleh M.A. Thermal Degradation of Azobenzene Dyes. Results in Chemistry. 2023.
2. Nguyen T.; Saleh M.A. Detection of Azo Dyes and Aromatic Amines in Women Undergarment. Journal of Environmental Science and Health, Part A 2016, 51(9), 744–753. DOI: 10.1080/10934529.2016.1170446.