Simultaneous identification of nine carcinogenic dyes from textiles by liquid chromatography/electrospray ionization mass spectrometry via negative/positive ion switching mode.

A method has been established by using liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI/MS/MS) for simultaneous separation and identification of nine carcinogenic dyes (Acid Red 26, Direct Blue 6, Direct Black 38, Direct Red 28, Basic Red 9, Basic Violet 14, Disperse Blue 1, Disperse Orange 11 and Disperse Yellow 3) prohibited in textile materials under EU 2002/371/EC decision. Three selected reaction monitoring (SRM) transitions and negative/positive ion switching mode in one single analysis was applied to differentiate between the dyes of different classes. A lower limit of detection was achieved at 0.025-0.25 mg kg(-1) of positive ESI dyes and 0.005-0.025 mg kg(-1) of negative ESI dyes. The accurate and sensitive identification of the nine dissimilar analytes was achieved by combining the characterized ions and retention time of the standards, for example, the characterized ions of M - xNa, M -Cl and M + H, respectively were detected for the the sulfonated (acid and direct), basic and disperse dyes. The chromophore groups of azo, triphenylmethane and anthraquinone in precursor ions were found to have fragmented in SRM mode. These results demonstrated a sensitive, accurate and rapid identification.