Large-volume sample stacking for on-capillary sample enrichment in the determination of naphthalene- and benzenesulfonates in real water samples by capillary zone electrophoresis

Abstract

We investigated the on-line preconcentration of a test mixture of 15 substituted and unsubstituted naphthalene(NSs) and benzenesulfonates (BZSs) by large-volume sample stacking (LVSS). Analyses were carried out by capillary zone electrophoresis (CZE) with on-column UV detection. In particular, we focused on how experimental variables such as the inside diameter of the capillary, the volume of sample introduced and polarity switching influenced the enrichment procedure. The best results were obtained when 300 nl were injected and stacked using a bubble cell capillary. Under these conditions, LVSS increased the detector response of conventional hydrodynamic injection by a factor of 40. The limits of detection of the method were between 5 and 10 microg l(-1). Determinations were reproducible, in terms of peak area and migration time, under such conditions. The performance of the method was examined by determining NS and BZS in real samples, such as tap, river and surface waters and inflow/outflow waters from a water treatment plant. Real samples were injected directly into the CZE column with little or no preparation.

Sample stacking revisited: A personal perspective

“…Many techniques have been proposed in the literature to perform large-volume sample stacking [35][36][37][38][39][40][41]. A switching valve can be used to physically remove the stacked sample zone into the separation BGE.…”

“…There are several excellent review articles published recently on the theory and applications of sample stacking and related concentration techniques [2,[35][36][37][38][39][40][41][42][43]. Nevertheless, the proliferation of terminology and misunderstanding of electrokinetic fundamentals in many publications unfortunately confuses and frustrates a newcomer.…”

Highly sensitive detection of melamine and its derivatives by capillary electrophoresis coupled with online preconcentration techniques

“…It is demonstrated herein for the first time that two kinds of online preconcentration techniques including large-volume sample stacking-sweeping (LVSS-S) [36][37][38][39] and selective-exhaustive injection (SEI-S) [38,39] were employed in CE-UV system, and they were compared for their effectiveness in the detection of MM and its derivatives. Based on our results, LVSS-S can be used for the simultaneous detection of the four compounds with the detection limits ranging from 0.08 to 0.92 mg/mL.…”

Capillary Electrophoresis for the Simultaneous Determination of Metals by Using Ethylenediamine Tetraacetic Acid as Complexing Agent and Vancomycin as Complex Selector

“…Therefore, it was unsuitable for the analysis of trace metals in real samples, especially environmental samples. Increasing the optical path length by incorporating a bubble cell [7][8][9] or a Z-shaped cell 10,11 is one of the means to improve the sensitivity of UV detection. Z-shaped cell, usually a bent capillary, with a few millimeters of the capillary parallel to the optical path can provide a higher sensitivity, but the loss of resolution prevents this method from further development.…”