Optimization of a solid‐phase microextraction procedure for the determination of herbicides by micellar electrokinetic chromatography

Abstract

The use of a different optimization procedure that involves Experimental Design (ED) and Artificial Neural Networks (ANN) for the off-line coupling solid-phase microextraction-micellar electokinetic chomatography (SPME-MEKC) is presented. This combination of ED and ANN, mathematical tools not previously used in SPME-MEKC optimization, allowed us to obtain good extraction efficiencies in the SPME procedure for the determination of a group of eleven triazine herbicides in groundwater samples. Both extraction and desorption steps were carried out by solution stirring at 900 rpm. Optimal conditions for the off-line SPME procedure were: extraction with a poly(dimethylsiloxane)/divinylbenzene SPME fiber for 120 min, 10% (w/v) NaCl, desorption time 40 min, and 70% (v/v) of methanol/buffer as desorption mixture. Detection limits lay between 0.80 microg L(-1) and 4.89 microg L(-1). Finally, the optimized method was applied to the determination of these compounds in spiked and non-spiked groundwater samples using a previously optimized MEKC separation.

Recent advances in capillary electrophoresis and capillary electrochromatography of pollutants

“…The combined use of SPE and online preconcentration strategies is shown to overcome the sensitivity problems usually linked to CE analysis of herbicides in environmental samples [80,83,84,115]. As an example, Hernández-Borges et al [115] reported the ultrasensitive determination of five herbicides in stagnant water by CE and UV detection combined with SPE and online preconcentration using stacking with matrix removal.…”

“…Among various CE modes utilized, MEKC was the most commonly used for determination of pesticides [78,79,89] and herbicides [37,38,81,83,84,[155][156][157][158]. SeguraCarretero et al [78] utilized MEKC with diode-array detector (DAD) for determination of imidacloprid and its metabolite 6-chloronicotinic acid in greenhouse air.…”

“…Offline sample preconcentration has been employed to alleviate this issue through the use of SPE [21,47,[76][77][78][79][80][81][82][83], solid-phase microextraction (SPME) [48,49,68,82,84], liquid-liquid extraction (LLE) [52], liquid-liquid-liquidmicroextraction (LLLME) [20], continuous-flow liquid membrane extraction (CFLME) [85], and microporous membrane liquid-liquid extraction (MMLLE) [59]. The use of SPE has been a common approach for sample preparation prior to the separation and detection of pesticides [47,[78][79][80][81][82][83].…”

Combining solid‐phase microextraction and on‐line preconcentration‐capillary electrophoresis for sensitive analysis of pesticides in foods

“…As indicated above, SPME prior to CE for pesticide analysis has only been used in three works [10][11][12]. SPME has several advantages over SPE or liquid-liquid extraction (e.g., faster, more simple, and environmentally friendly, etc.)…”

“…Likewise, off-line preconcentration procedures based on solidphase microextraction (SPME) [10][11][12], SPE [13], or cloud point extraction (CPE) [14] have also been developed for being used with CE analysis. The use of these different preconcentration strategies prior to CE and their application to pesticide analysis has been recently reviewed by our group [15].…”