An HPLC-MS/MS multi-analyte method for the determination of 70 azo dye-derived primary aromatic amines for the assessment of migration from dyed textiles

We present a sensitive and selective HPLC-MS/MS multi-analyte method for the determination of azo dyes and primary aromatic amines (PAAs) migrating from textiles into sweat simulant. Azo dyes in the migrate are quantified indirectly by determining the associated PAAs that are released upon reduction with dithionite. Migrates are analyzed following dilution with water or after reduction without further clean-up. This significantly reduces sample preparation time as well as the consumption of consumables and organic solvent. Salts contained in the samples are effectively removed by chromatography. The extraction-free sample preparation overcomes problems of low recoveries during sample clean-up as observed with diatomaceous earth media according to DIN EN 14362-1. Inclusion or omission of the reduction step allows to differentiate between PAAs formed as cleavage products of migrated azo dyes and contaminant PAAs directly released from textiles. In addition, omission of the reduction step enables quantification of PAAs containing nitro and azo groups. The developed method covers 59 PAAs in ESI positive mode, including the 22 PAAs specified under REACH, and additional 11 PAAs in ESI negative mode. Limits of quantification range between 0.014 and 40.5 µg L^-1 (0.003-9 mg of migrated substance per kg of textile with a grammage of 150 g m^-2), featuring about ten times higher sensitivity than previously reported methods. The developed analytical approach was applied to determine the migration of PAAs from 83 textile market samples. REACH-listed PAAs were only detected at trace levels (up to 0.037 mg kg^-1), but other PAAs such as 2-aminobenzene sulfonic acid migrated in amounts of up to 21.3 mg kg^-1. Finally, results were compared with the reductively extractable PAA contents of the textiles, revealing migrating fractions between < 0.1% and 56%.