Analysis of selected constituents in methanolic extracts of Hypericum perforatum collected in different localities by capillary ITP-CZE.

The on-line combination of CZE with capillary ITP (ITP-CZE) was used for the separation and quantification of selected flavonoids and phenolic acids in Hypericum perforatum leaves and flowers collected in six different localities in Slovakia. The leading electrolyte in the ITP preseparation step was 10 mM HCl with Tris as counterion (pH* 7.2). The terminating electrolyte was 50 mM boric acid of pH* 8.2 (adjusted with barium hydroxide). The BGE in the electrophoretic step contained 25 mM beta-hydroxy-4-morpholinopropanesulfonic acid (MOPSO), 50 mM Tris, 65 mM boric acid, pH* 8.3. The content of methanol in all electrolytes was 20% v/v. The total time of the analysis (including the preseparation step) was approximately 35 min. The rectilinear calibration ranges were between 0.125 and 5.0 microg/mL with kaempferol as internal standard. The correlation coefficients ranged between 0.9912 (for quercitrin and chlorogenic acid) and 0.9988 (for isoquercitrin). The RSD values are between 0.86 and 7.78% (n = 6) when determining rutin and quercetin (4 microg/mL). The optimized method was employed for the assay of flavonoids in medicinal plant extract of different collections of Hypericum perforatum haulm. The variability of the content of the active components depending on the place of collection was confirmed.

Determination of ibuprofen and flurbiprofen in pharmaceuticals by capillary zone electrophoresis.

Capillary zone electrophoresis with spectrophotometric detection was used for the determination of ibuprofen (IB) and flurbiprofen (FL) in pharmaceuticals. The separation was carried out in a fused silica capillary (60 cm x 100 microm i.d. effective length 45 cm) at 30 kV with UV detection at 232 nm. The optimized background electrolyte was 20mM N-(2-acetamido)-2-aminoethanesulfonic acid (ACES) with 20mM imidazole and 10mM alpha-cyclodextrin of pH 7.3. 2-Naphthoxyacetic acid was used as internal standard. A single analysis took less than 5 min. Rectilinear calibration ranges were 2-500 mg l(-1) for IB and 1-60 mg l(-1) for FL. The relative standard deviations (R.S.D.) values (n=6) were 1.53% for IB and 1.29% for FL (for 200 mg l(-1) IB and 10 mg l(-1) FL). This validated method has been successfully applied for the routine analysis of 10 commercially available pharmaceutical preparations (syrup, tablets, cream and gel).

Separation and determination of clotrimazole, methylparaben and propylparaben in pharmaceutical preparation by micellar electrokinetic chromatography.

In this study, micellar electrokinetic chromatography (MEKC) method was developed for the determination of clotrimazole (CLO), methylparaben (MP) and propylparaben (PP) in a pharmaceutical preparation. Separation was carried out in a fused silica capillary (60 cm x 75 microm i.d.) at 25 kV with UV detection at 212 nm. Optimized background electrolyte (BGE) was 15 mM phosphate buffer (pH 7.2) containing 30 mM sodium dodecyl sulfate (SDS) as a surfactant. Rectilinear calibration ranges were 50-500 mg l(-1) for CLO, 10-100 mg l(-1) for MP and 2.5-25 mg l(-1) for PP. The total analysis time was < 12 min.

Assay of phenolic compounds in red wine by on-line combination of capillary isotachophoresis with capillary zone electrophoresis.

The on-line combination of capillary zone electrophoresis (CZE) with capillary isotachophoresis (ITP) increases significantly the separation capability and sensitivity of capillary electrophoresis. This technique was used for separation and quantification of fourteen selected natural constituents in red wine belonging to flavonoids and phenolic acids. The leading electrolyte (LE) in the ITP pre-separation step was 10 mM HCl of pH* 7.2 with Tris as counterion, the terminating electrolyte (TE) was 50 mM boric acid of pH* 8.2 (adjusted with barium hydroxide). The background electrolyte in the electrophoretic step contained 25 mM beta-hydroxy-4-morpholinopropanesulfonic acid (MOPSO), 50 mM Tris, 15 mM boric acid and 5 mM beta-cyclodextrin of pH* 8.5. The content of methanol in all electrolytes was 20% (v/v). For exact timing of the transfer of isotachophoretically stacked analyte zones into the CZE column and for the control of the residual amount of leading and terminating ITP electrolytes picric acid was used as coloured marker. The R.S.D. values (n = 6) ranged between approximately 0.1% (for 0.25 microg ml(-1) rutin) and approximately 11% (for 0.25 microg ml(-1) of quercitrin). Detection limits were 30 ng mi(-1) for phenolic acids, quercitrin and rutin, 100 ng ml(-1) for quercetin, kaempferol and epicatechin and 250 ng ml(-1) for catechin. A single analysis took 45 min.