Separation of very hydrophobic compounds by hydrophobic interaction electrokinetic chromatography

Ahuja, Eric S.; Foley, Joe P.

doi:10.1016/0021-9673(94)80054-5

Cited by 40 publications

(19 citation statements)

References 28 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, several factors, such as organic solvent, salt concentration, and temperature, will alter the CMC of surfactants. It was reported that an increase of CMC occurs while adding acetonitrile to the mixtures [25,26]. In the present case, the acetonitrile concentration was 80% (by volume) in the electrolyte and no micelle was observed since the current was increased by adding SDS and CTAB to the electrolyte.…”

Section: Surfactantsmentioning

confidence: 46%

Chiral recognition ability of an (S)‐naproxen‐ imprinted monolith by capillary electrochromatography

Liu

Wang

et al. 2005

Electrophoresis

View full text Add to dashboard Cite

The racemic naproxen was selectively recognized by capillary electrochromatography (CEC) on an (S)-naproxen-imprinted monolith, which was prepared by an in situ thermal-initiated polymerization. The recognition selectivity of a selected monolith strictly relied on the CEC conditions involved. The factors that influence the imprinting selectivity as well as the electroosmotic flow (EOF), including the applied voltage, organic solvent, salt concentration and pH value of the buffer, column temperature, and surfactant modifiers were systematically studied. Once the column was prepared, the experiment results showed that the successful chiral recognition was dependent on CEC variables. For example: the recognition could be observed in acetonitrile and ethanol electrolytes, while methanol and dimethyl sulfoxide (DMSO) electrolytes had no chiral recognition ability. The buffer with pH values of 2.6 or 3.0 at a higher salt concentration had chiral recognition ability. Column temperatures of 25-35 degrees C were optimal. Three surfactants, sodium dodecyl sulfate (SDS), cetyltrimethylammonium bromide (CTAB), and polyoxyethylene sorbitan monolaurate (Tween 20), can improve the recognition. Baseline resolution was obtained under optimized conditions and the column efficiency of the later eluent (S)-naproxen was 90 000 plates/m.

show abstract

Section: Surfactantsmentioning

confidence: 46%

Chiral recognition ability of an (S)‐naproxen‐ imprinted monolith by capillary electrochromatography

Liu

Wang

et al. 2005

Electrophoresis

View full text Add to dashboard Cite

show abstract

“…2.2 min. This indicated that the porphyrin methyl esters did have some interaction with the SDS molecules (possibly in the form of SDS monomers), but the interaction was not strong enough to allow for the differential migration of individual esters at 60 mM SDS, possibly due to the small size of the porphyrin methyl esters [20].…”

Section: Mekc (Hydroorganic Solvents)mentioning

confidence: 97%

“…Ahuja and Foley [20] have reported the successful CE separation of highly hydrophobic compounds via hydrophobic/solvophobic interaction between a number of long-chained alkyl aryl ketones and SDS monomers, using a running buffer that contained 50 mM SDS and 50% ACN. In the present study, only one peak appeared in the electropherogram when the ACN content was increased to 50% (Fig.…”

Section: Mekc (Hydroorganic Solvents)mentioning

confidence: 99%

Investigation of solvent effects in capillary electrophoresis for the separation of biological porphyrin methyl esters

Chang

Huie

2005

Electrophoresis

View full text Add to dashboard Cite

The effects of organic solvents on the capillary electrophoresis (CE) separation of a number of important biological porphyrin methyl esters - six weakly basic, hydrophobic cyclic tetrapyrroles possessing two and four to eight methyl ester groups around the periphery of the porphyrin ring - were investigated in the mode of micellar electrokinetic chromatography (MEKC), microemulsion electrokinetic chromatography (MEEKC), and nonaqueous CE. In aqueous MEKC, partial separation of the six neutral porphyrin methyl esters was obtained with an organic modifier (acetonitrile) in the concentration range between 20 and 40%, in which sodium dodecyl sulfate (SDS) molecules might be present in the form of SDS micelles and/or SDS micelle-like aggregates. Relatively stable SDS micelles can be formed in nonaqueous MEKC using formamide as the separation medium, but the separation of the target analytes remained unsatisfactory. Improved resolution of all six porphyrin methyl esters was obtained using MEEKC with the running buffer consisting of 0.8% w/w n-heptane (oil phase), 2.25% w/w SDS and 1.0% w/w Brij 35 (mixed surfactant), 6.6% w/w 1-butanol (cosurfactant), and 30% v/v 2-propanol (second cosurfactant), but reproducibility in terms of peak areas for certain porphyrins (especially uroporphyrin I octamethyl ester) was found to be very poor. Best separation performances were achieved with nonaqueous CE separations in which the weakly basic porphyrin methyl esters were protonated under strongly acidic conditions (e.g., using 10 mM perchloric acid) in mixed organic solvents. For example, using a 50:50 mixture of methanol and acetonitrile as the separation medium, baseline separation of all six (positively charged) porphyrin methyl esters can be obtained within 3 min and the average precision (RSD, N = 13) in terms of migration time and peak area were 0.55 and 2.16%, respectively.

show abstract

“…The concentrations of surfactants were chosen based on the values used in the literature. [29] Although the critical micellar concentration (CMC) values determined in pure water are 8.3 mm for SDS, [21] 0.6 mm for Tween 20 [26] and 0.2 mm for Tween 80, [31] it has been shown that the addition of buffers and various amounts of acetoni- www.chemeurj.org trile result in an increase of the CMC value. [29,28,31] Preliminary experiments showed that the addition of Tween 80 was not having any significant effect on either the reaction rate or the imprinting factor.…”

Section: à4mentioning

confidence: 99%

“…[29] Although the critical micellar concentration (CMC) values determined in pure water are 8.3 mm for SDS, [21] 0.6 mm for Tween 20 [26] and 0.2 mm for Tween 80, [31] it has been shown that the addition of buffers and various amounts of acetoni- www.chemeurj.org trile result in an increase of the CMC value. [29,28,31] Preliminary experiments showed that the addition of Tween 80 was not having any significant effect on either the reaction rate or the imprinting factor. Reactions carried out with SDS, with its anionic residues, were showing the highest catalytic activity in terms of reaction rate, but the imprinting efficiency, indicated by the ratio between the apparent rate constants for the imprinted (MIP) and non-imprinted nanogels (NIP) was drastically reduced.…”

Section: à4mentioning

confidence: 99%

Tuning Molecular Recognition in Water‐Soluble Nanogels with Enzyme‐Like Activity for the Kemp Elimination

Servant

Haupt

Resmini

2011

Chemistry A European J

View full text Add to dashboard Cite

The synthesis and characterization of water-soluble imprinted nanogels with enzyme-like activity in the Kemp elimination is reported together with studies that demonstrate how the recognition properties, morphology, and catalytic activity of the nanoparticles can be tuned by the use of surfactants, such as Tween 20. A detailed kinetic investigation is carried out, which shows clear evidence of saturation kinetics and rule out the effects of mass transfer. This is supported by characterization of the polymeric materials that confirms the morphological changes resulting from the use of surfactants. These results provide an important tool for the development of nanoparticle-based, new catalyst-mimicking enzymes.

show abstract

Separation of very hydrophobic compounds by hydrophobic interaction electrokinetic chromatography

Cited by 40 publications

References 28 publications

Chiral recognition ability of an (S)‐naproxen‐ imprinted monolith by capillary electrochromatography

Chiral recognition ability of an (S)‐naproxen‐ imprinted monolith by capillary electrochromatography

Investigation of solvent effects in capillary electrophoresis for the separation of biological porphyrin methyl esters

Tuning Molecular Recognition in Water‐Soluble Nanogels with Enzyme‐Like Activity for the Kemp Elimination

Contact Info

Product

Resources

About