Trace determination of benzalkonium chlorides in river and wastewater by capillary electrophoresis following solid-phase extraction coupled with salting-out extraction

Trace levels analysisbenzalkonium chlorides (BAKs) in river water and wastewater treatment plants (WWTP) effluents were determined by capillary electrophoresis (CE) following solid-phase extraction (SPE) and salting-out extraction. Salting-out extraction using an appropriate ratio of sodium chloride (NaCl) and acetonitrile (ACN) mixed with concentrated SPE elutant was capable of providing more than 500-fold enhancement in detection sensitivity. The ratios of ACN and NaCl for salting-out extraction were investigated and optimized. Matrix interference was eliminated by salting-out extraction. Limits of quantitation of BAK homologues were achieved at 0.1 μg/L in 250 mL water samples. Recoveries of BAKs in various spiked water samples ranged from 70% to 84% with relative standard deviation (RSD) less than 9%. Trace amounts of total BAKs were detected in river water and WWTP effluent samples ranging from 27 to 145 μg/L at the first time by CE.