Determination of dimethindene enantiomers in pharmaceuticals by capillary electrophoresis with carboxyethyl-beta-cyclodextrin.

Cyclodextrin-mediated capillary zone electrophoresis in a hydrodynamically closed separation system with suppressed electroosmotic flow and UV absorbance photometric detection was developed for a high effective separation and quantitation of dimethindene enantiomers in various pharmaceutical formulations (solution, gel, capsules). The running buffer consisted of epsilon-aminocaproic acid (20 mmol/l) adjusted to pH 4.5 with acetic acid, negatively charged carboxyethyl-beta-cyclodextrin (2.5 mg/ml), serving as chiral selector, and 0.1% (w/v) methylhydroxyethylcellulose, serving as an electroosmotic flow suppressor. The proposed method was successfully validated appraising parameters of sensitivity, linearity, precision, accuracy/recovery and robustness and it is useful for routine use.

[Separation of dimetinden enantiomers in drugs by means of capillary isotachophoresis]. / Separacia enantiomérov dimetindenu v liekoch kapilárnou izotachoforézou.

Capillary isotachophoresis was employed to separate and determine dimethinden enantiomers in various dosage forms. Several types of chiral selectors were tested in various electrolyte systems of different composition and different pH. The optimal leading electrolyte was composed of 10 mmol/l potassium acetate and acetic acid to achieve pH 4.8 with an addition of 4 mmol/l carboxyethyl-beta-cyclodextrin as the chiral selector and 0.2% of methylhydroxyethylcellulose (m-HEC) to suppress the electroosmotic flow. The terminating electrolyte was betaalanine of a concentration of 5 mmol/l. The evaluation included the precision, correctness, linearity, robustness, and selectivity of the elaborated ITP method. The pretreatment of the sample prior to analysis consisted in the dissolution and dilution of the appropriate dimethinden-containing dosage form with demineralized water to achieve the required concentration. Such a pretreated sample was directly dosed into the apparatus.

Comparison of capillary zone electrophoresis and isotachophoresis determination of dimethindene enantiomers in pharmaceuticals using charged carboxyethyl-beta-cyclodextrin as a chiral selector.

Charged cyclodextrin-mediated capillary electrophoretic methods (capillary zone electrophoresis [CZE] and isotachophoresis [ITP]) in a hydrodynamically closed separation system with suppressed electroosmotic flow and UV absorbance photometric detection (for CZE) or conductivity detection (for ITP) were developed for a highly effective separation and quantitation of dimethindene enantiomers in various pharmaceutical formulations (solution, gel, capsules). Optimized electrolyte systems were based on low-mobility buffer constituents (epsilon-aminocaproic acid, beta-alanine, potassium acetate, acetic acid), negatively charged (at pH > 4.5) carboxyethyl-beta-cyclodextrin (CE-beta-CD), serving as chiral selector, and methylhydroxyethylcellulose, serving as an electroosmotic flow suppressor. Complete enantioseparations of dimethindene in the presence of low concentrations of CE-beta-CD (2.5 mg/ml in CZE, 6.0 mg/ml in ITP) clearly indicated a role of charge of this chiral selector in enantioresolution. It also outlined the potential of charged CD-derivatives as chiral selectors for various CE techniques. The proposed methods were successfully validated, appraising parameters of sensitivity, linearity, precision, accuracy/recovery, and robustness, and then, they were applied to pharmaceutical samples. Consistent results obtained by both CE methods indicate their usefulness for routine use.

[Isotachophoretic determination of desloratadine in tablets and syrup]. / Izotachoforetické stanovenie desloratadínu v tabletách a sirupe.

Desloratadine was determined in two dosage forms (tablets and syrup) with the use of the method of capillary isotachophoresis. Several electrolyte systems of varying composition and varying pH were tested. Two electrolyte systems were selected for the validation of the method and determination of desloratadine in real samples. In both electrolyte systems, the precision, correctness, linearity, robustness, and selectivity of the ITP method were evaluated. The pre-treatment of the sample prior to analysis consisted in dissolving and diluting the pertinent desloratadine-containing dosage form with demineralized water to the required concentration. This pre-treated sample was fed directly to the apparatus.

Determination of promethazine hydrochloride in pharmaceuticals by capillary isotachophoresis.

Capillary isotachophoresis (ITP) in cationic regime of the separation with conductometric detection has been used for the separation and determination of promethazine hydrochloride (PRO) in commercial mass-produced pharmaceutical preparations. Several electrolyte systems of different compositions and pH were examined and the optimized ITP electrolyte system consisted of 10 mmol/l of potassium acetate adjusted to pH 4.8 with acetic acid as the leading electrolyte with electroosmotic flow (EOF) suppressing additive, 0.2% (w/v) methylhydroxyethylcellulose (m-HEC), and 5 mmol/l of beta-alanine as the terminating electrolyte. The proposed electrophoretic method was successfully validated. It was convenient for the sensitive, simple, rapid, and highly reproducible assay of promethazine. The calibration graph relating the ITP zone length to concentration of the analyte was rectilinear in the range of 40-200 mg/l of the drug standard, with a coefficient of determination r(2)=0.9992. The relative standard deviation (RSD) was 1.12% (n=6) when determining 100 mg/l of PRO in standard sample. Good quantitation was obtained in short analysis time (a single analysis took 6 min). The recoveries of drug from samples were found to be 97.22% (tablets), 99.72% (injections), and 99.14% (syrup). The minimal sample pretreatment and low running cost make the proposed ITP method a good alternative to commonly used analytical methods.

[Dimethindene determination in various dosage forms by means of capillary isotachophoresis]. / Stanovenie dimetindenu v rôznych liekových formách kapilárnou izotachoforézou.

Capillary isotachophoresis was employed to determine dimethindene in various dosage forms. Several electrolyte systems of varying compositions and varying pH were tested. For validation of the method and the determination of dimethindene in real samples (gel, drops, capsules), two electrolyte systems were selected. Precision, correctness, linearity, robustness, and selectivity of the ITP method were evaluated for both electrolyte systems. The pre-treatment of the sample prior to analysis consisted in dissolving and diluting the pertinent dosage form containing dimethindene with demineralized water to the required concentration. The sample adjusted in this way was directly dosed into the apparatus.

[Use of capillary isotachophoresis for the determination of pheniramine in granulated powders]. / Vyuzitie kapilárnej izotachoforézy na stanovenie feniramínu v granulovaných práskoch.

The method of capillary isotachophoresis was used to assay pheniramine in granulated powders. Several electrolyte systems of different composition and different pH were tested. Two electrolyte systems were selected for the validation of the method and pheniramine determination in real samples. Precision, accuracy, linearity, robustness, and selectivity of the ITP method for both electrolyte systems were evaluated. The pre-treatment of samples prior to analysis consisted in dissolving pheniramine-containing granulated powder in demineralized water and subsequent diluting with demineralized water to required concentration.

Capillary zone electrophoresis determination of loratadine in tablets.

A capillary electrophoretic method was developed for the determination of loratadine in pharmaceutical formulations. Capillary zone electrophoresis (CZE) separation and UV absorbance photometric detection were carried out in a 160 mm capillary tube with a 300 microm internal diameter, hydrodynamically (membrane) closed. The influences of pH, carrier cation and counter ion on the migration parameters of loratadine were studied and the following conditions were selected: 24 mmol/l glycine as a carrier cation, 1.6 mmol/l citric acid and 84 mmol/l acetic acid as counter ions at pH 3.2, 100 microA and 25 degrees C. The proposed electrophoretic method was successfully validated. It was convenient for the sensitive, simple, rapid and highly reproducible assay of loratadine. The determination of loratadine in tablet forms was demonstrated as an application of the method. CZE analysis was completed within 6 min. The detection limit of loratadine was 1.96 micro/mol/l at a 240 nm detection wavelength and the relative standard deviation for its determination was 0.6% for migration time and 1.1% for peak area. CZE in a hydrodynamically closed separation system, used for the first time for the analysis of loratadine, should also be convenient for complex biological sample applications, as it is easily combinable online with the purification CE modes (e.g. ITP).

[Simultaneous isotachophoresis determination of dioxopromethazine and phenylephrine in eye drops]. / Izotachoforetické stanovenie dioxoprometazínu vedla fenylefrínu v ocnej instilácii.

Dioxopromethazine and phenylephrine were determined simultaneously in eye drops using the method of capillary isotachophoresis. Two electrolyte systems with different compositions and pH were examined. Prior to analysis, the eye drops are diluted with water in a ratio 1:50. Precision, correctness, linearity, robustness, and selectivity of the ITP method were evaluated for both electrolyte systems.

Capillary isotachophoresis of cystine in urine with on-line isotachophoresis sample pretreatment.

Capillary isotachophoresis (ITP) with on-line isotachophoresis sample pretreatment and conductivity detection has been proposed as a method for the separation, detection and determination of cystine present in urine. Sample pretreatment was achieved using a 90 mm FEP capillary tube with a 800 microm internal diameter. ITP separations and conductivity detection were carried out in a 160 mm capillary tube with a 300 microm internal diameter, filled with a hydrochloric acid leading electrolyte and glycine terminating electrolyte, at 50 microA and 25 degrees C. The results show that the proposed method is suitable for resolution of cystine from matrix interferents present in the urine samples and is able to detect it at 10(-4) mol/l concentrations by a universal detection technique after removal of a significant part of the anionic constituents of the sample migrating in the on-line coupled capillary isotachophoresis stack. This simple ITP procedure for monitoring cystine in urine samples requires no sample preparation. This makes it an alternative to the currently used procedures.

[Optimal conditions for determination of L-cystine using capillary isotachophoresis]. / Optimalizácia podmienok pre stanovenie L-cystínu kapilárnou izotachoforézou.

The compound L-cystine was determined using the method of capillary isotachophoresis in two electrolyte systems. Precision, correctness, linearity, robustness, and selectivity of ITP were evaluated. The results of ITP measurements were compared with the results obtained by means of the standard pharmacopoeial methods.