Determination of sulfonated azo dyes in groundwater and industrial effluents by automated solid-phase extraction followed by capillary electrophoresis/mass spectrometry

Abstract

One monosulfonated (Mordant Yellow 8) and seven disulfonated azo dyes (Acid Red 1, Mordant Red 9, Acid Red 13, Acid Red 14, Acid Red 73, Acid Yellow 23 and Acid Blue 113) were determined in spiked groundwater samples and industrial effluents by automated solid-phase extraction followed by capillary electrophoresis with UV detection and by capillary electrophoresis/mass spectrometry (CE/MS). The MS parameters were optimized to achieve maximum sensitivity and minimum fragmentation. The main ions observed were losses of Na+ cations replaced by hydrogen atoms. Two polymeric solid-phase extraction cartridges (Isolute ENV+ and LiChrolut EN) were compared for the preconcentration of 300 or 500 ml water samples. The recoveries varied from 64 to 80% for all dyes, with the exception of Acid Blue 113 and Acid Yellow 23, the recoveries of which varied from 15 to 34% when using Isolute ENV+. The protocol developed in this work was applied to the determination of sulfonated azo dyes in real samples from industrial effluents. The method detection limit ranged from 10 to 150 μg l-1 for CE/UV detection and from 100 to 800 μg l-1 for CE/MS under time-scheduled selected-ion monitoring conditions, with the exception of Acid Red 73 (>1700 μg l-1), which exhibited a low response. © John Wiley & Sons, Ltd.