Micellar electrokinetic chromatography for simultaneous determination of six corticosteroids in commercial pharmaceuticals

Abstract

We have developed a micellar electrokinetic chromatography (MEKC) method using bile salts for the simultaneous determination of six corticosteroids, including betamethasone, cortisone, prednisolone, 6alpha-methylprednisolone, triamcinolone, and prednisone. The separation was performed using borate buffer containing sodium cholate and sodium deoxycholate. Several parameters were studied, including bile salt concentrations, concentrations and pH of borate buffer, and analytical voltages. In method validation, calibration curves were linear over a range of 10-100 microM for each corticosteroid. The RSD (relative standard deviation) and RE (relative error) were all less than 5% for intra- and interday assays. The limit of detection of each analyte was 5 microM. The recoveries were greater than 95%. Application of this method for quality control of commercial tablets also proved to be feasible. All analytical values fall within the labeled amount of 90-110% for betamethasone and prednisolone, and of the labeled amount of 92.5-107.5% for 6alpha-methylprednisolone, as required by the United State Pharmacopeia 25 (USP 25).

Cationic surfactants for micellar electrokinetic chromatography: 1. Characterization of selectivity using the linear solvation energy relationships model

“…Whether or not this is the cause, the result is interesting because the McGowan characteristic volume is generally one of the dominant factors controlling retention and thus selectivity in EKC. The importance of cohesiveness is seen in the separation of larger more hydrophobic compounds such as steroids, where more cohesive phases are more successful in resolving these compounds [35,36]. Additionally, reduction of the v value increases the relative importance of other factors that control separation selectivity such as acid/base and dipolar interactions.…”

MEKC: An update focusing on practical aspects

“…In fact, mixed micelles are less hydrophobic that pure SDS micelles, so interactions for hydrophobic solutes are weaker. Mixtures of bile salts [148,149] and of SDS with other anionic surfactants such as sodium di(2-ethylhexyl) sulfosuccinate (DOSS, Fig. 3) [54] have also been used as mixed micellar systems.…”

Cationic surfactants for micellar electrokinetic chromatography: 2. Representative applications to acidic, basic, and hydrophobic analytes

“…The separation of corticosteroids is important due to their prevalent use for replacement therapy of adrenocortical insufficiency and nonspecific treatment of inflammatory and allergic conditions. These steroids are traditionally difficult to separate by MEKC requiring the use of a mixed micellar system consisting of SDS and a bile salt or the use of an organic modifier [12][13][14][15][16][17][18]. Currently, the most successful micellar phase to separate steroids is the bile salt sodium cholate; bile salts are better able to separate steroids because of their greater interaction with polar compounds and relatively high cohesivity [12].…”

“…These steroids are traditionally difficult to separate by MEKC requiring the use of a mixed micellar system consisting of SDS and a bile salt or the use of an organic modifier [12][13][14][15][16][17][18]. Currently, the most successful micellar phase to separate steroids is the bile salt sodium cholate; bile salts are better able to separate steroids because of their greater interaction with polar compounds and relatively high cohesivity [12]. An LSER analysis of sodium cholate showed that the v and s values, which pertain to the phase's cohesiveness and ability to interact with polar compounds, are 2.27 and 20.60 [18], respectively.…”