Introduction of migration indices for identification: Chiral separation of some β‐blockers by using cyclodextrins in micellar electrokinetic capillary chromatography

Abstract

Because of the different physiological impact that stereoisomers may have, it is often vital to separate these forms from one another. Because of their structural similarity, the separation is usually difficult to achieve and zones may elute very close to each other. This is a particular problem in capillary electrophoresis, where the repeatability of absolute migration times is fairly poor, mainly due to the irreproducibility of the electroosmotic flow. The separation is usually repeatable, however, and when the disturbing effects are eliminated by using a migration index system incorporating two marker compounds the identification of the enantiomers becomes extremely good. Relative standard deviation (RSD) values less than 0.1% for the migration index of each enantiomer were obtained in both intra-day and day-to-day (6 days) studies. The best separation was achieved with the electrolyte solution made of 40 mM borate, 32 mM sodium dodecyl sulfate (SDS), 12 mM beta-cyclodextrin (beta-CD), and 6 mM alpha-cyclodextrin (alpha-CD) at pH 9.3.

Selection of migration parameters for a highly reliable assignment of bands of isoforms of erythropoietin separated by capillary electrophoresis

“…It can be seen that in some cases migration time showed a good accuracy (e.g., 93% for set 14). However, as observed by other authors for repeatabilities of migration times [17] a good result could be coincidental and this was not the general behavior, being this parameter the one providing the lowest accuracy. Much higher percentage of correct assignments was provided by the rest of migration parameters.…”

“…It is commonly agreed that variations in EOF are one of the main causes of changes observed in migration time [15,17,18]. In turn, according to Eq.…”

“…Some of the studies include the comparison of different parameters such as migration time, relative migration, electrophoretic mobili-ty, actual mobility, and relative mobility [11][12][13][14][15][16]. A different approach makes use of the effective electrophoretic mobility of known markers to determine the electrophoretic mobility of the compound of interest [17,18]. A computer program to normalize electropherograms to reference conditions has also been developed [19].…”

Quantitation of talinolol and other β‐blockers by capillary electrophoresis for in vitro drug absorption studies

“…There have been numerous attempts made by others to achieve separation of the talinolol enantiomers. The use of neutral cyclodextrins (CDs) as chiral selectors such as b-CD and g-CD as well as heptakis(2,3,6-tri-O-methyl)-a-CD (TM-a-CD) did not lead to separation of the enantiomers of talinolol [17][18][19]. The use of hydroxypropyl-a-CD (HP-a-CD), or hydroxypropyl-g-CD (HP-g-CD) remained without success too [20][21][22].…”

Application of h-point standard addition method for simultaneous spectrophotometric determination of hydrochlorothiazide and propranolol

“…8,9 In the case of propranolol, several methods have been proposed for determination of propranolol using atomic absorption spectrometric, 10 spectrofluorimetry, 11 conductometric titration and chromatography. [12][13][14][15][16] To our knowledge, there is not a proposed method for simultaneous determination of hydrochlorothiazide and propranolol in pharmaceutical dosage forms and biological fluids. Since UV-Visible spectrophotometry is a rapid, sensitive and inexpensive analytical tool, it is appropriate for dosage control of pharmaceutical preparations.…”