On-line ion pair solid-phase extraction of electrokinetic multicommutation for determination of trace anion surfactants in pond water

An electrokinetic multicommutation system is presented in this paper for the preconcentration and determination of trace anion surfactants of alkylbenzenesulfonate (ABS) in pond water, including electro-osmotic pumping, on-line ion pair solid-phase extraction (IP-SPE), bubble removing and directly spectrophotometric determination. Tetrabutylammonium bromide (TBAB) as an ion-pairing reagent was added into sample solutions to improve ABS retention on C18 extraction column. Several extraction parameters, including the concentration of different eluents and ion-pairing reagents, the retention and elution flow rate, and the eluent volume, were discussed in detail. A homemade gas-liquid separator was employed to remove bubbles from the eluate flow before spectrophotometric detection. In this way, the bubble interference in coupling reversed-phase SPE with spectrophotometry can be eliminated. For 15 ml sampling volume, the detection limit of ABS, relative standard deviation and preconcentration factor of the proposed method were 10 ng ml−1 (3σ, N = 7), 3.7% (N = 8), and 65, respectively.