Hydrophobic interaction electrokinetic chromatography for the separation of polycyclic aromatic hydrocarbons using non-aqueous matrices

Koch, Jeremy T.; Beam, Brooke M.; Phillips, K. Scott; Wheeler, John F.

doi:10.1016/s0021-9673(01)00521-0

Cited by 18 publications

(7 citation statements)

References 37 publications

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“…However, because PAHs are highly hydrophobic compounds and strongly associated with the hydrocarbon phase, they are difficult to be separated by some common surfactants [7]. Therefore, Koch et al [8] increased the solubility of PAHs by the addition of organic solvents, but satisfactory resolution was not achieved because of peak tailing. Warner and coworkers [10] have successfully separated 16 PAHs [9] and 12 monomethyl-benz[a]anthracene isomers by exploring a high-purity T-type polymerized surfactant with an undecenyl (C 11 ) and a sulfate group.…”

Section: Introductionmentioning

confidence: 99%

Comparison of two capillary electrophoresis online stacking modes by analysis of polycyclic aromatic hydrocarbons in airborne particulates

Song

Peng

Lin

2006

J of Separation Science

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Original PaperComparison of two capillary electrophoresis online stacking modes by analysis of polycyclic aromatic hydrocarbons in airborne particulates Naphthalene, fluorene, pyrene, anthracene, phenanthrene, and chrysene were successfully separated by CD-modified MEKC (CD-MEKC) using 20 mM borate (pH 9.0) containing 90 mM SDS and 75 mM b-CD. Two online stacking methods, i. e., sweeping and field-enhanced sample injection (FESI), were explored to enhance the detection sensitivity. The influences of some crucial parameters in sweeping and FESI procedures were investigated. For FESI method, a plug of water and low-conductivity sample matrix was used to increase the stacking efficiency. Compared with the sweeping method, FESI can increase the sensitivity in the range of 10 -20-fold. The proposed method was used for the analysis of polycyclic aromatic hydrocarbons in airborne particulates.

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Section: Introductionmentioning

confidence: 99%

Comparison of two capillary electrophoresis online stacking modes by analysis of polycyclic aromatic hydrocarbons in airborne particulates

Song

Peng

Lin

2006

J of Separation Science

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“…When concentrations are decreased, the separation becomes worse, and finally in 2 mmol/L acetic acid and 2 mmol/L TBA acetate BGE (theoretical ionic strength 2 mmol/L) the peaks are almost comigrating (data not shown). Seemingly pyrene has a small (positive) mobility under present conditions probably due to interaction with the BGE cation (TBA Note that complexation of pyrene and tetraalkylammonium ions (tetrahexylammonium and tetraheptylammonium) has been reported in the literature [43][44][45][46][47]. NM peak appears at all acetate concentrations just before the negative peak produced by the solvent (or by an eigenzone with mobility very close to zero [ 48,49]), which indicates that it is uncharged in all conditions.…”

Section: Selection Of Experimental Conditionsmentioning

confidence: 70%

Electromigration of a heteroconjugated imidazole–acetate complex in ACN

Porras

Jussila

2007

Electrophoresis

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ACN is an extremely poor hydrogen bond donor and therefore the anions dissolved in it are solvated mainly by other hydrogen bond donors (e.g. uncharged acids) possibly present in the solution. Under properly selected experimental conditions stabilization via hydrogen bonding can be used for separation in CE as has been demonstrated for uncharged acids by several authors. Electromigration based on heteroconjugation can be of importance, e.g. when aqueous separation medium cannot be used due to stability reasons. It also allows CE to be used as a tool for solution chemistry measurements, if the required physicochemical properties of the studied system are known or they can be predicted with sufficient accuracy by existing theories. In the present work we showed that also an uncharged base can stabilize an anion via hydrogen bonding in ACN. In the setup imidazole was chosen as a model base and acetate ion as complexing anion in equimolar acetic acid-acetate buffer. The resulted hydrogen-bonded imidazole-acetate complex (i.e. heteroconjugate) possesses a charge and can thus migrate in CE. It was shown that the studied complexation in ACN is sensitive to competition by other hydrogen bond donors such as water and methanol. On the other hand, acetone, which is a poor hydrogen bond donor, did not have much effect on the complexation. To take the effect of ionic strength on mobility into account, mobilities of the imidazole-acetate complex measured at various ionic strengths were corrected to zero ionic strength by the aid of conductivity equation. A fit of the 1:1 binding isotherm to the ionic strength corrected mobility versus acetate concentration data led to rather good correlation. However, x-reciprocal linear transformation of the binding isotherm showed nonlinearity, which could be partly explained by homoconjugation of acetic acid and acetate ion. Since the homoconjugation constant for acetic acid under present experimental conditions was not available, theoretical simulations were used to demonstrate the effects of homoconjugation. The possibility of multiple complexation of imidazole was discussed as well.

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“…The presence of organic solvent can also reduce the interaction between CD and analyte, and thus result to a decrease in enantiomeric selectivity as well as sweeping effect. One of the reasons for the addition of organic solvent prior to CE is the improvement in solubility of hydrophobic samples . Solvents are also used for protein precipitation as sample preparation of biological samples and for prevention of protein adsorption into the silica capillary walls .…”

Section: Introductionmentioning

confidence: 99%

Sweeping of alprenolol enantiomers with an organic solvent and sulfated β‐cyclodextrin in capillary electrophoresis

Rabanes

Quirino

2013

Electrophoresis

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Sweeping, an on-line sample concentration technique in CE, is the picking and accumulation of analytes by the pseudostationary phase or complexing additive. In the presence of an electric field, the analytes concentrated at the additive front that initially penetrated the sample zone. Here, we describe the sweeping of cationic alprenolol enantiomers using sulfated β-CD and organic solvent. The separation solution contained the anionic additive while ACN was in the sample solution. With fused silica capillaries, positive polarity, and solutions buffered at pH 3, the direction of the enantiomers' effective electrophoretic mobility was the same as the electrophoretic mobility (or electrophoretic mobility without additive). When the amount of ACN in the sample was increased (i.e. 60%), the interaction between the analytes and additive became negligible. This caused the sweeping boundary to shift from the electrophoretically moving β-CD front to the zone between the sample and separation solution. The equation that described the narrowing of injected sample zone was derived. The performance of sweeping with 60% ACN in the sample was then studied under different operating conditions (e.g. type of injection, injection time, and CD concentration). The low interaction between enantiomers and additive gave only moderate increases in sensitivity (approximately tenfold), but was improved when field enhancement was used during electrokinetic injection. With a conductivity difference (separation/sample solution) of 70 and a short injection time of 30 s at 20 kV, peak improvements of >100-fold was easily achieved.

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Hydrophobic interaction electrokinetic chromatography for the separation of polycyclic aromatic hydrocarbons using non-aqueous matrices

Cited by 18 publications

References 37 publications

Comparison of two capillary electrophoresis online stacking modes by analysis of polycyclic aromatic hydrocarbons in airborne particulates

Comparison of two capillary electrophoresis online stacking modes by analysis of polycyclic aromatic hydrocarbons in airborne particulates

Electromigration of a heteroconjugated imidazole–acetate complex in ACN

Sweeping of alprenolol enantiomers with an organic solvent and sulfated β‐cyclodextrin in capillary electrophoresis

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