In‐capillary solid‐phase extraction–capillary electrophoresis for the determination of chlorophenols in water

Abstract

A novel CE method combined with SPE in a single capillary was developed for analysis of chlorophenols in water. A frit of 0.5 mm was first made by a sol-gel method, followed by packing a SPE sorbent in the inlet end of the capillary. Two phenol derivatives, 2,4-dichlorophenol and 2,4,5-trichlorophenol, were used as the model compounds. By loading sample solutions into the capillary, the two chlorophenols were extracted into the sorbent. They were desorbed by injecting only about 4 nL of methanol. Finally, the analytes were separated by conventional CE. The technique provided a concentration enhancement factor of over 4000-fold for both chlorophenols. The detection limits (S/N = 3) of 2,4-dichlorophenol and 2,4,5-trichlorophenol were determined to be 0.1 ng/mL and 0.07 ng/mL, respectively. For replicate analyses of 5 ng/mL of 2,4-dichlorophenol, within-day and between-day RSDs of migration time, peak height and peak area were in the range of 1.8-2.0%, 4.0-4.4% and 4.1-4.6%, respectively. The method shows wide linear range, acceptable reproducibility and excellent sensitivity, and it was applied to the analyses of spiked river water samples. The capillary packed with the SPE sorbents can be used for more than 400 runs without performance deterioration.

Recent advances in CE and CEC of pollutants

“…As outlined in Section 3, several studies using CE to analyze phenolic compounds in environmental matrices focused primarily on the improvement of sensitivity and sample clean-up techniques [34,68,69,72]. A number of studies reported the use of microchip CE for the determination of phenols [36,38,42,46].…”

“…CE remains an important area of investigation for the analysis of these pollutants [34,36,38,39,42,46,61,68,69,72,82,87]. As outlined in Section 3, several studies using CE to analyze phenolic compounds in environmental matrices focused primarily on the improvement of sensitivity and sample clean-up techniques [34,68,69,72].…”

“…The use of a preconcentrating device at the head of the capillary has been explored in a number of recent works [66,68,70,72]. For example, Zhang et al [68] developed an in-capillary SPE-CE method by incorporating a 0.5 mm-long SPE sorbent into the inlet end of a capillary for analysis of chlorophenols in water [68]. The LODs of 2,4-dichlorophenol and 2,4,5-trichorophenol were 4000 times lower than the conventional CE limits.…”

Design and applications of coupled SPE‐CE

“…4b) [44,[49][50][51][52][53][54], or the preconcentrator is inside the separation capillary (Fig. 4c) [55][56][57][58][59][60][61][62][63][64][65][66]. The first inline SPE-CE system with a packed SPE bed was introduced by Guzman et al [49].…”

Electrical field‐assisted solid‐phase extraction coupled on‐line to capillary electrophoresis‐mass spectrometry

“…In fact, complete system integration for unattended extraction, separation and detection is now possible. The SPE-CE coupling has been used in combination with three different types of treatments, namely: (i) batch procedures [4,5]; (ii) automatic procedures, which usually involve on-line [6,7] or at-line coupling of a flow system to CE equipment [7][8][9][10]; (iii) and procedures performed within the capillary (on-capillary preconcentration) [11][12][13]. The latter two are especially interesting for routine laboratories as they simplify the analyst's work and reduce errors due to human intervention.…”