The separation of herbicides by micellar electrokinetic capillary chromatography

Wu, Quanji; Claessens, H.A.; Cramers, C.A.M.G.

doi:10.1007/bf02290454

Cited by 56 publications

(13 citation statements)

References 57 publications

(44 reference statements)

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“…Soon after its introduction, MEKC's potential for the separation of achiral ionic species with very similar electrophoretic mobilities as well as neutral and charged enantiomers was also recognized [5][6][7][8][9][10][11][12][13][14][15][16]. In parallel with the rapidly broadening areas of successful applications (e.g., pharmaceutical compounds [17][18][19][20][21], derivatized amino acids [22][23][24], water-and fat-soluble vitamins [25][26][27][28], and herbicides [29]) was the investigation of a wide variety of alternative PSPs including modified SDS micelles [30,31], non-SDS conventional micelles [2,32], mixed micelles [33,34], charged CDs [35], microemulsions [36], macrocyclic compounds [37], polymer micelles [38,39], bicelles [40,41], linear polymers [16], dendrimers [42], and pseudostationary ion-exchange phases [16].…”

Section: Introductionmentioning

confidence: 99%

Compositional effects on electrophoretic and chromatographic figures of merit in electrokinetic chromatography with cetyltrimethylammonium bromide/sodium octyl sulfate vesicles as the pseudostationary phase. Part 1: Effect of the phase ratio

et al. 2008

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The effect of the phase ratio on the electrophoretic and chromatographic properties of unilamellar vesicles comprised of cetyltrimethylammonium bromide (CTAB) and sodium octyl sulfate (SOS) was investigated in EKC. The surfactant concentration of the vesicles was 0.9, 1.2, 1.5, and 1.8% w/v, with a mole ratio of 1:3.66 (CTAB/SOS). Results were compared to those obtained using SDS micelles at concentrations of 1.0% (w/v, 35 mM) and 1.5% (52 mM). The CTAB/SOS vesicles (0.9-1.8% w/v) provided a significantly larger elution range (5.7 < or = t(ves)/t(0) < or = 8.7) and greater hydrophobic (methylene) selectivity (2.8 < or = alpha(CH2) < or = 3.1) than SDS micelles (3.1 < or = t(mc)/t(0) < or = 3.3; alpha(CH2) = 2.2). Whereas the larger elution range can be attributed to the 25% reduction in EOF due to the interaction of unaggregated CTAB cations and the negatively charged capillary wall, the higher methylene selectivity is likely due to the lower concentration of water expected in the CTAB/SOS vesicle bilayer compared to the Palisades layer of SDS micelles. For a given phase ratio, CTAB/SOS vesicles are somewhat less retentive than SDS micelles, although retention factors comparable to those observed in 1.0-1.5% SDS can be obtained with 1.5-1.8% CTAB/SOS. A linear relationship was observed between phase ratio and retention factor, confirming the validity of the phase ratio model for these vesicles. Unique polar group selectivities and positional isomer shape selectivities were obtained with CTAB/SOS vesicles, with both types of selectivities being nearly independent of the phase ratio. For four sets of positional isomers, the elution order was always para < ortho < meta. Finally, the thermodynamics of solute retention was qualitatively similar to that reported for other surfactant aggregates (micelles and microemulsions); the enthalpic contribution to retention was consistently favorable for all compounds, whereas the entropic contribution was favorable only to hydrophobic solutes.

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Section: Introductionmentioning

confidence: 99%

Compositional effects on electrophoretic and chromatographic figures of merit in electrokinetic chromatography with cetyltrimethylammonium bromide/sodium octyl sulfate vesicles as the pseudostationary phase. Part 1: Effect of the phase ratio

et al. 2008

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“…Since Brij 35 possesses polar polyether moities these mixed micelles introduce hydrogen-bonding interactions [48] in addition to the hydrophobic interaction between analytes and micelles in pure SDS-systems. Although resolution improvement for the phenoxy acids was shown before [8] and was also expected for the sulfonylureas, separation rather deteriorated.…”

Section: Brij 35mentioning

confidence: 79%

“…With a few exceptions authors restrict themselves to one class of pesticides, such as triazines [1][2][3], hydroxy-or methoxymetabolites of triazines, either alone or in combination with their parent compounds [4][5][6][7], phenoxy acids [8][9][10][11], phenylurea- [12], sutfonylurea-[13, 14J or dipyridylium-pesticides [15,16]. The application of capillary zone electrophoresis (CZE) dominates over micellar electrokinetic chromatography (MEKC).…”

mentioning

confidence: 99%

Separation of 18 modern plant protectants using cyclodextrin modified micellar electrokinetic chromatography including an ion-pairing reagent

Stutz

Malissa

1998

Mikrochim Acta

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Abstract.A cyclodextrin-modified micellar electrokinetic chromatography separation for 18 different pesticides (metsuifuron-methyl, rimsulfuron, thifensulfuron-methyl, desethylatrazine, desisopropylatrazine, atrazine, simazine, terbuthylazine, 2,4-D, MCPR MCPB, dicamba, linuron, alachlor, metolachlor, orbencarb, propiconazole, prochloraz) from eight different substance classes with very varying chemical and physical properties is presented. In particular acidbase characteristics and water-octanol distribution coefficients diverge in wide ranges. 3-cyclodextrin was successfully employed as a modifier in separating the hydrophobic analytes. Peak distortion of some neutral analytes, which is devoted to the methanol content of the sample zone, was reduced by increasing the SDS concentration. Methanol in the sample is necessary for a better solubility of the hydrophobic pesticides. Few optima of SDS concentration exist allowing the separation of sulfonylureas as well as phenoxy acids and hydrophobic pesticides. An improved resolution of the sulfonylureas was achieved with tetramethylammonium chloride, which was used as an ion-pairing reagent.' Final operating conditions for the separation of all these plant protectant compounds by MEKC in just one single run are a 27mmolL -1 phosphate buffer, pH 8.03, with 95mmolL-1SDS, 5rmnolL =1 /3-cyclodextrin and 10 mmolL -1 tetramethylammonium-chloride.Key words: capillary electrophoresis, micellar electrokinetic chromatography, multi-residue-analysis, pesticide analysis. * To whom correspondence should be addressedThe relevance of high performance capillary electrophoresis (HPCE) applied in multi-residue methods for trace analysis of plant protectants in environmental samples has attained growing interest in the past few years. With a few exceptions authors restrict themselves to one class of pesticides, such as triazines [1-3], hydroxy-or methoxymetabolites of triazines, either alone or in combination with their parent compounds [4][5][6][7], phenoxy acids [8-11 ], phenylurea-[12], sutfonylurea-[13, 14J or dipyridylium-pesticides [15,16]. The application of capillary zone electrophoresis (CZE) dominates over micellar electrokinetic chromatography (MEKC). For neutral analytes or more complex pesticide mixtures MEKC is selected [17][18][19][20][21][22]. HPCE is more versatile than HPLC and GC since there is nearly no restriction to certain pesticide classes and therefore derivatization becomes unnecessary. Within the HPCE-techniques MEKC is more likely to separate complex substance mixtures than CZE, which is restricted to charged substances. This is due to various surfactants and modifiers that can be selected and combined in MEKC to optimize separation.In the field of multi-residue separation several successful attempts are published which show the general viability of MEKC technique. These approaches, however, were confined to mixtures of hydrophilic and moderately hydrophobic pesticides [18,21] including one hydrophobic pesticide at maximum [22]. If more than one hydrophobic ...

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“…A number of analytical methods have been reported for determination of phenoxyacid herbicides in different matrices using high-performance liquid chromatography HPLC [3][4][5], gas chromatography GC-MS [6][7][8][9][10][11], capillary electrophoresis [12][13][14][15][16] and micellar electrokinetic chromatography [17]. Because of the complex structure of matrix and the presence of pesticides in small quantities, different procedures for extracting and preconcentration of pesticides from samples are needed to develop.…”

Section: Introductionmentioning

confidence: 99%

Kinetic spektrophotometric determination of 2,4-dichlorphenoxyacetic acid based on its inhibitory effect on the oxidation of sulfanilic acid by hydrogen peroxide

Miletic¹,

Pecev-Marinkovic²,

Grahovac³

et al. 2015

Adv techn

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A kinetic spectrophotometric method for measuring 2,4-dichlorphenoxyacetic acid (2,4-D) is described in this study. The proposed method is based on the inhibitory effect of 2,4-D on the oxidation of sulfanilic acid by hydrogen peroxide in the presence of Co(II) ion, which was monitored at 370 nm. The variables affecting the rate of the reaction were investigated and the optimum conditions were established. 2,4-D can be measured in the range of 0.07 -2.35 μg mL -1 and from 2.35 to 23.50 μg mL -1 with the detection limit of 0.004 μg mL -1 . This method was used to determined traces of 2,4-D in baby fruit juices. The HPLC method was used like a comparative method to verify the results. The results obtained by the proposed method were compared with those obtained by HPLC using UV -DAD detection and they showed a good agreement.

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The separation of herbicides by micellar electrokinetic capillary chromatography

Cited by 56 publications

References 57 publications

Compositional effects on electrophoretic and chromatographic figures of merit in electrokinetic chromatography with cetyltrimethylammonium bromide/sodium octyl sulfate vesicles as the pseudostationary phase. Part 1: Effect of the phase ratio

Compositional effects on electrophoretic and chromatographic figures of merit in electrokinetic chromatography with cetyltrimethylammonium bromide/sodium octyl sulfate vesicles as the pseudostationary phase. Part 1: Effect of the phase ratio

Separation of 18 modern plant protectants using cyclodextrin modified micellar electrokinetic chromatography including an ion-pairing reagent

Kinetic spektrophotometric determination of 2,4-dichlorphenoxyacetic acid based on its inhibitory effect on the oxidation of sulfanilic acid by hydrogen peroxide

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