[HPLC separation of racemic basic esters of alkoxyphenylcarbamic acid using two teicoplanin chiral stationary phases]. / HPLC separácia racemátov bazických esterov alkoxyfenylkarbámovej kyseliny pouzitím dvoch teikoplanínových chirálnych stacionárnych fáz.

This paper presents the results obtained with the use of two chiral stationary phases (CSP), based on a glycopeptide antibiotic agent--teicoplanin aglycone (CHIROBIOTIC TAG) and methylated teicoplanin aglycon m-TAG. Twenty-one racemic mixtures of 1-methyl-2-piperidinoethylesters of 2-, 3- and 4-alkoxyphenylcarbamic acid were examined. The investigation included interaction between separated substances and CSP, and the effect of separation of the enantiomers under study on the value of the resolution factor (R(ij)) under identical chromatographic conditions with the use of the method of high-performance liquid chromatography (HPLC). On the basis of obtained results, it is possible to report that CSP-CHIROBIOTIC TAG is more advantageous for these racemates, because it does not contain a saccharide part, with decrease the possibility of non-polar interactions which exert a negative effect on the R(ij) value.

Kinetic study of derivatives of phenylcarbamic acid enantiomers in rabbit blood serum using an on-line coupled column liquid chromatographic system.

An on-line coupled HPLC system is described for the kinetic study of the enantiomers of 1-methyl-2-piperidinoethylesters of 2-, 3- and 4-alkoxyphenylcarbamic acid in rabbit blood serum. The method involves three steps: (i) off-line pre-concentration and cleanup step, (ii) analytical separation of the racemate on a reversed-phase stationary phase, and (iii) separation of the enantiomers on a teicoplanin aglycone chiral stationary phase (Chirobiotic Tag). The limit of the determination with standard solutions was approximately 5.0 microg/ml. In vitro degradation studies of enantiomers have demonstrated differences in the concentration of the enantiomers after the treatment. The rate constants of R(-)- and S(+)-forms of enantiomers (the same as the position of alkoxychain) were, not significantly different. The number of carbon atoms had an influence on the degradation kinetics.

[Chiral separation of drugs based on macrocyclic antibiotics using HPLC, supercritical fluid chromatography (SFC) and capillary electrochromatography (CEC)]. / Chirálne separácie niektorých lieciv na báze makrocyklických antibiotík v HPLC, SFC a CEC.

Separation of enantiomers by means of high-performance liquid chromatography (HPLC), supercritical fluid chromatography (SFC), and capillary electrochromatography (CEC) is of great importance in pharmaceutical analyses. In recent years, separation of various types of racemates employs most frequently chiral stationary phases based on macrocyclic antibiotics. This class of chiral selectors includes vancomycin, teikoplanin, ristocetin A, teikoplanin without saccharide components, avoparcin, etc. The review paper describes the properties of selected antibiotics, the effect of chromatographic conditions on enantioselectivity (effect of the composition of the mobile phase, effect of pH of the mobile phase, effect of temperature), and the study of possible mechanisms of interaction, which play an important role in the separation of enantiomers. Examples of the use of macrocyclic antibiotics in the separation of various compounds by means of the HPLC, SFC, and CEC methods follow.

[Effect of saccharides in the teicoplanin stationary phase on the separation of enantiomers of the phenylcarbamic type using HPLC]. / Vplyv sacharidových castí v teikoplanínovej stacionárnej fáze na separáciu niektorých enantiomérov fenylkarbámového typu metódou HPLC.

The paper presents the results obtained with the use of two chiral stationary phases (CSP) based on a macromolecular antibiotic agent--teikoplanin containing saccharide parts (CHIROBIOTIC T) and teikoplanin without saccharide parts (CHIROBIOTIC TAG). Racemic mixtures of 1-methyl-2-piperidinoethyl esters of 2-, 3-, and 4-alkoxyphenylcarbamic acids were examined. The investigation included interactions between separated substances and CSP, and the effect of separation of the enantiomers under study on the value of the differentiation factor (Rij) under identical chromatographic conditions with the use of the method of high-performance liquid chromatography (HPLC). On the basis of the obtained results, it is possible to report that CSP-CHIROBIOTIC TAG is more advantageous for the substances of the type of 1-methyl-2-piperidinoethyl esters of 2-, 3-, and 4-alkoxyphenylcarbamic acids, because it does not contain a saccharide part, which decreases the possibility of non-polar interactions which exert a negative effect on the Rij value.

Coupled column chromatography for separation and determination of enantiomers of phenylcarbamic acid derivatives in serum.

Columns packed with vancomycin coupled to an achiral C18 column and beta-cyclodextrin were used for the separation and the determination of enantiomers of alkoxysubstituted esters of phenylcarbamic acid in blood serum. The method involves off-line SPE, the separation of the racemate on a reversed-phase stationary phase, and the separation of the enantiomers on a chiral stationary phase. The limit of detection was 1.0 microg/ml for the vancomycin column and 10.0 microg/ml for the beta-cyclodextrin column in standard solution. In vitro degradation studies of enantiomers demonstrated a difference in the concentation of the enantiomers after the treatment. It was found that the rate constants of R(-)- and S(+)-forms of enantiomers are not significantly different.

[Enantiomeric separation of drugs based on macrocyclic antibiotics]. / Enantiomérne separácie lieciv na báze makrocyklických antibiotík.

The present review paper describes the properties of the macrocyclic antibiotics vancomycin, teikoplanin, and ristocetin A, which can be used as stationary phases for separation of the enantiomers of drugs containing a stereogenic centre. It analyzes the results obtained in the separation of amino acids, its derivatives, loxiglumide, clenbuterol, practolol, carnitine, levodopa, methyldopa, ceftazidine, alkoxyphenylcarbamic acid derivatives, dichloroprop, ketoprofen, warfarin, and ergot alkaloids by means of high-performance liquid chromatography (HPLC).