Selectivity in Micellar Reversed-Phase Liquid Chromatography: C-18 and C-8 Alkyl Bonded Phases

Lavine, Barry K.; Hendayana, Sumar; Tetreault, Jonathan

doi:10.1021/ac00092a025

Cited by 30 publications

(13 citation statements)

References 16 publications

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“…The alkyl tail of negatively charged surfactants such as SDS interact with the bonded groups leaving their charged head groups orientated at the stationary phase surface, forming a hydrophilic layer. Conversely, the head groups of positively charged surfactants interact with the bonded phases leaving their alkyl tails uppermost, retaining the hydrophobicity of the stationary phase [27].…”

Section: Effect Of Surfactant Type and Concentrationmentioning

confidence: 99%

A review of the background, operating parameters and applications of microemulsion liquid chromatography (MELC)

Marsh

Clark

Altria³

2005

J of Separation Science

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A review of the background, operating parameters and applications of microemulsion liquid chromatography (MELC) Microemulsions are dispersions of nanometre-sized droplets of an immiscible liquid within another liquid. Droplet formation is facilitated by the addition of surfactants and often also cosurfactants. Microemulsions are classified as either oil-in-water (O/W) (oil droplets such as octane dispersed throughout aqueous buffer) or water-in-oil (W/O) (aqueous droplets in oil such as hexane). Both microemulsion types have been used as mobile phases for separation in microemulsion HPLC (MELC). There has been a recent increase of interest in this area with new applications and developments such as gradient elution and optimisation of methods using experimental design. O/W microemulsions have been employed as eluents for RP-HPLC while W/O microemulsions have been used for normal phase chromatography. Separations can have superior speed and efficiency to conventional HPLC modes while offering a unique selectivity with excellent resolution. The capability for quantitative and stability-indicating analysis has also been demonstrated. Specific advantages include the ability to operate at low UV wavelengths and elimination of the need for an equilibration rinse between gradients. Operational issues associated with the use of MELC have been identified including the need to add salt to the gradient eluent, relatively high back-pressures and increased need for equipment cleaning compared to conventional RP eluent. This report details the different microemulsion types and compositions used and their reported applications. The use of gradient and isocratic elution is described. The effects on separations of varying operating parameters such as temperature, oil type and concentration, surfactant type and concentration, sample solvent, column type, and organic solvent addition will be discussed and illustrated.

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Section: Effect Of Surfactant Type and Concentrationmentioning

confidence: 99%

A review of the background, operating parameters and applications of microemulsion liquid chromatography (MELC)

Marsh

Clark

Altria³

2005

J of Separation Science

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“…Retention in MLC has been shown to be correlated to surfactant type and the concentration of surfactant in the mobile phase. [11,15] Solute retention in MLC generally decreases with increasing surfactant concentration, but the rate of decrease can vary considerably from one solute to another.…”

Section: Micellar Liquid Chromatographymentioning

confidence: 99%

Column Classification and Selection for the Determination of Antibiotics by Micellar Liquid Chromatography

Rambla-Alegre

Carda‐Broch

Esteve‐Romero

2009

Journal of Liquid Chromatography & Related Technologies

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Seven commercially available: Zorbax C 18 , Kromasil C 18 , C 8 , cyano, phenyl, monolithic and amino stationary phases columns, have been characterized and classified into broadly similar types to simplify column choice. The results were evaluated employing cluster analysis, which shows several interesting groups based on distances (Minkowski and Euclidean) in agreement with the manufacturer's claims: chain density of the stationary phase used, and the presence or not a silica base. Finally, results showed that C 18 columns offer the best chromatographic characteristics for separation and quantification of antibiotics in micellar liquid chromatography.

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“…Ž The same was proposed to occur in micellar liquid chromatography Gonzalez et al, . 1992;Lavine et al, 1994 . The reduced affinity for ODS in the presence of adsorbed surfactants can be explained by the observation that the hydrophobicity of aliphatic Ž moieties is reduced by ionic groups in their vicinity Noordman et al, 1993;Hol et al, .…”

Section: Adsorbed Rhamnolipid Reduces the Affinity Of Fluorene And Phmentioning

confidence: 99%

Facilitated transport of a PAH mixture by a rhamnolipid biosurfactant in porous silica matrices

Noordman¹,

Bruining²,

Wietzes³

et al. 2000

Journal of Contaminant Hydrology

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Ž. The facilitated transport of a mixture of three polycyclic aromatic hydrocarbons PAH Ž . naphthalene, fluorene, and phenanthrene by a rhamnolipid biosurfactant was determined with silica, octadecyl-coated silica, and humic acid-coated silica columns. The retardation factors for Ž . the contaminants in the absence of rhamnolipid ranged from 1.8 naphthalene with silica to 708 Ž . phenanthrene with octadecyl-coated silica . The retardation factors for phenanthrene were up to eightfold lower in the presence of 500 mgrl rhamnolipid compared to the situation where no rhamnolipid was present. The facilitated transport of the contaminants in the presence of rhamnolipid could be predicted by accounting for sorption, solubilization and admicellar sorption. In the octadecyl-coated matrix, transport of fluorene and phenanthrene was enhanced even in the Ž . presence of sub-micellar solution of rhamnolipid 20 mgrl , showing that adsorbed surfactant reduced the affinity of these compounds to this stationary phase. Linear free-energy relations Ž . LFERs indicated that the matrix-water, micelle-water, and admicelle-water partitioning constants for PAH were correlated with their 1-octanol-water partitioning constants. These correlations were used to simulate the facilitated transport of contaminants of varying hydrophobicity by a surfactant. It was concluded that surfactants have the greatest transport facilitating effect on the more hydrophobic components. The effectiveness of surfactants for enhancing removal of the less Ž . hydrophobic compounds log K -3.4 may considerably be reduced due to admicellar sorption.

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Selectivity in Micellar Reversed-Phase Liquid Chromatography: C-18 and C-8 Alkyl Bonded Phases

Cited by 30 publications

References 16 publications

A review of the background, operating parameters and applications of microemulsion liquid chromatography (MELC)

A review of the background, operating parameters and applications of microemulsion liquid chromatography (MELC)

Column Classification and Selection for the Determination of Antibiotics by Micellar Liquid Chromatography

Facilitated transport of a PAH mixture by a rhamnolipid biosurfactant in porous silica matrices

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