Analysis of Disperse Dyes Using the ACQUITY Arc System with PDA and Mass Detection, and Empower Software

Significance of the topic

Disperse dyes are widely used in textiles, paper, toys and other consumer products, yet their low molecular weight and potential for azo-linked carcinogenic amine formation pose health and regulatory concerns. Reliable detection and impurity profiling of these dyes is essential for consumer safety and compliance with standards such as DIN 54231.

Objectives and study overview

This study applies the DIN 54231 protocol to a mixture of nine common disperse dyes using a dual-flow path chromatography system equipped with photodiode array (PDA) and mass detection. The goals were to demonstrate enhanced selectivity, to exceed the prescribed detection limits, and to identify trace impurities within dye standards.

Methodology

A gradient reversed-phase separation was conducted on an XBridge C18 column (2.1×150 mm, 5 µm) at 30 °C with a 30-minute runtime. Mobile phase A was 10 mmol ammonium acetate (pH 3.6), mobile phase B was acetonitrile. The flow rate was 0.3 mL/min and the injection volume 5 µL.

• PDA detection: 210–800 nm
• MS detection: ACQUITY QDa in ESI+ mode, capillary voltage 1.2 kV, cone voltage 10 V, scan range 100–600 m/z with selected ion recording

Instrumentation

• ACQUITY Arc System
• 2998 Photodiode Array Detector
• ACQUITY QDa Detector
• XBridge C18 Column (2.1×150 mm, 5 µm)
• Empower 3 Chromatography Data Software

Main results and discussion

The method achieved baseline separation for seven of nine dyes, while disperse yellow 3 and orange 3 coeluted. Mass detection via selective ion recording resolved the coelution using unique m/z values. Detection limits for all dyes surpassed the DIN 54231 requirement of 0.7 mg/L. Full-scan MS revealed an impurity (peak A) at m/z 267 in the disperse blue 3 standard, confirmed by UV spectrum matching and a subsequent single-component analysis. A second impurity (m/z 254) was also detected in that standard.

Benefits and practical applications

The combined PDA and QDa MS approach ensures confident identification of coeluting compounds and trace impurities without extensive method redevelopment. This workflow supports fast, robust screening and quantitation of disperse dyes in quality control laboratories and regulatory testing of consumer goods.

Future trends and possibilities of application

• Integration with high-resolution mass spectrometry for structural elucidation
• Expansion to broader dye libraries and degradation products
• Real-time monitoring and inline QA in production lines
• Automation and artificial intelligence for peak annotation and trend analysis

Conclusion

The ACQUITY Arc System with dual PDA and mass detection delivers enhanced sensitivity, selectivity and impurity profiling for disperse dyes, exceeding regulatory detection limits and simplifying compliance workflows.

References

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5. Cooper J, Marchand J. Waters Application Note No. 720004492EN; 2015.
6. Waters Corporation. ACQUITY Arc System Brochure No. 720005393EN; 2015.