Micellar Liquid Chromatography: Fundamentals

Abstract

The reversed phase liquid chromatography (RPLC) mode with surfactant above the critical micellar concentration (CMC) has been called micellar liquid chromatography (MLC). In pure micellar systems, the retention behavior is explained by considering three phases or environments: surfactant‐modified stationary phase, bulk aqueous solvent, and micellar pseudo‐phase. Surfactant adsorption on the porous RPLC packing affects chromatographic retention, owing to the change of diverse surface properties of the stationary phase. In pure micellar systems, the retention behavior is explained by considering three phases or environments: surfactant‐modified stationary phase, bulk aqueous solvent, and micellar pseudo‐phase. In pure micellar mobile phases, water‐insoluble nonpolar solutes or species strongly bound to surfactant monomers do not participate significantly in the aqueous environment of the three‐phase partitioning scheme. Some of the solutions proposed along the years to overcome these limitations have favored the potential of the technique, but they have not resulted in an extensive use.

Two liquid chromatographic approaches for the simultaneous determination of xipamide and its degradation product (2,6‐xylidine) using time‐programmed fluorescence detection

“…Biologically, MLC allows direct injection of biological fluids into the chromatographic system without prior treatment and this is due to solubilization of the protein using SDS. By contrast, in CLC, extraction with another organic solvent is usually recommended, consequently more environmental pollution may be observed …”

“…Micellar liquid chromatography (MLC) has various merits comparable with the conventional hydro‐organic method, including the estimation of huge numbers of compounds with different polarities . In addition, physiological samples can be directly injected into the chromatographic system . A tedious extraction procedure is not needed for the analysis of drugs in fats and oily injections .…”

Simultaneous isocratic separation of phenolic acids and flavonoids using micellar liquid chromatography

“…Micellar LC (MLC) is a an RPLC mode with a mobile phase consisting of an aqueous solution of surfactant above its critical micellar concentration (CMC) . After almost three decades of MLC experience, capabilities, and advantages derived from the use of micellar mobile phases are several : low cost, low toxicity, low volatility, rapid gradient capability , enhanced luminescence detection , high reproducibility, and direct on‐column injection of physiological samples . Furthermore, one of the most important advantages of MLC is the capability of simultaneous separation of compounds with a wide range of polarities without the need of gradient elution .…”

Dispersive liquid‐liquid microextraction for four phenolic environmental estrogens in water samples followed by determination using capillary electrophoresis

“…However, if no SDS was added, the four PEEs could not be separated with EOF; and a higher concentration of SDS caused longer migration time and distorted peaks. Although it is hardly possible to form conventional micelles for the 20 mM SDS in the 40% ACN solution [34], the appropriate concentration SDS (20 mM) played an important role for the separation. Accordingly, the named MEKC mode was possibly no longer applicable to the separation solution.…”

“…As observed, 40% (v/v) provided more smooth peak shape with higher resolution and relatively short separation time. Hence, 40% (v/v) ACN was chosen, although the critical micelle concentration of SDS is higher than 30 mM for a volume fraction of ACN of 40% [34]. However, if no SDS was added, the four PEEs could not be separated with EOF; and a higher concentration of SDS caused longer migration time and distorted peaks.…”