DETERMINATION OF SULFONATED AZO DYES IN GROUNDWATER AND INDUSTRIAL EFFLUENTS BY AUTOMATED SOLID-PHASE EXTRACTION FOLLOWED BY CAPILLARY-ELECTROPHORESIS MASS-SPECTROMETRY

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, Aci d Yellow 23 and Acid Blue 113) were determined in spiked groundwater s amples and industrial effluents by automated solid-phase extraction fo llowed by capillary electrophoresis with UV detection and by capillary electrophoresis/mass spectrometry (CE/MS). The MS parameters were opt imized to achieve maximum sensitivity and minimum fragmentation. The m ain ions observed were losses of Na+ cations replaced by hydrogen atom s. Two polymeric solid-phase extraction cartridges (Isolute ENV+ and L iChrolut EN) were compared for the preconcentration of 300 or 500 mi w ater 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 w hich varied from 15 to 34% when using Isolute ENV+. The protocol devel oped in this work was applied to the determination of sulfonated azo d yes in real samples from industrial effluents. The method detection li mit ranged from 10 to 150 mu g l(-1) for CE/UV detection and from 100 to 800 mu g l(-1) for CE/MS under time-scheduled selected-ion monitori ng conditions, with the exception of Acid Red 73 (>1700 mu g l(-1)), w hich exhibited a low response. (C) John Wiley & Sons, Ltd.